Histological Features Research Articles

Three-Dimensional Bio-Printed Tubular Tissue Using Dermal Fibroblast Cells as a New Tissue-Engineered Vascular Graft for Venous Replacement.

The current study was a preliminary evaluation of the feasibility and biologic features of three-dimensionally bio-printed tissue-engineered (3D bio-printed) vascular grafts comprising dermal fibroblast spheroids for venous replacement in rats and swine. The scaffold-free tubular tissue was made by the 3D bio-printer with normal human dermal fibroblasts. The tubular tissues were implanted into the infrarenal inferior vena cava of 4 male F344-rnu/rnu athymic nude rats and the short-term patency and histologic features were analyzed. A larger 3D bio-printed swine dermal fibroblast-derived prototype of tubular tissue was implanted into the right jugular vein of a swine and patency was evaluated at 4 weeks. The short-term patency rate was 100%. Immunohistochemistry analysis showed von Willebrand factor positivity on day 2, with more limited positivity observed on the luminal surface on day 5. Although the cross-sectional area of the wall differed significantly between preimplantation and days 2 and 5, suggesting swelling of the tubular tissue wall (both p < 0.01), the luminal diameter of the tubular tissues was not significantly altered during this period. The 3D bio-printed scaffold-free tubular tissues using human dermal or swine fibroblast spheroids may produce better tissue-engineered vascular grafts for venous replacement in rats or swine.

A Rare Inflammatory Myofibroblastic Tumor of the Spleen: A Case Report.

Inflammatory myofibroblastic tumors (IMTs) are rare, solid, potentially malignant lesions of uncertain etiology. Histologically, IMTs exhibit a combination of lymphocytes and inflammatory cells within a fibroblastic myxoid layer. The diagnosis of IMTs poses a challenge for various medical specialties, including surgeons, pathologists, and oncologists, due to their non-specific clinical presentation. Furthermore, radiologists face difficulties in interpreting computed tomography (CT) or magnetic resonance imaging (MRI) results, which often yield polymorphic and inconclusive findings. Ultimately, histopathologists play a crucial role in reaching a definitive diagnosis based on the tumor's histological characteristics. They are detected in every system of the human body, most commonly in the lungs. Here, we report an uncommon occurrence of IMT in the spleen of a patient with nonspecific abdominal pain. A 56-year-old Caucasian female presented to Konstantopouleio General Hospital of Nea Ionia, Athens, Greece, with abdominal pain and discomfort. The patient had no significant medical history and normal laboratory tests. An abdominal CT revealed a large mass in the spleen. A splenectomy was performed. Histopathological analysis of the tumor revealed IMTS. Splenic IMT is a rare benign tumor with moderate malignant potential. It lacks a distinct clinical presentation and is typically identified either incidentally or during the examination of abdominal pain.

Factors Associated With Prescription of Systemic Therapy in Real-world Patients With Metastatic Renal Cell Cancer Managed in a Rural Region.

Numerous new treatment options have been approved for metastatic renal cell carcinoma (mRCC) in the last decade. Nevertheless, not all patients receive systemic therapy. Certain patients present with very advanced disease, poor Eastern Cooperative Oncology Group performance status (ECOG PS), or severe comorbidity, i.e. factors that lead oncologists to prefer best supportive care (BSC) instead of systemic therapy. The aim of this quality-of-care study was to identify baseline factors (disparities) associated with receipt of systemic therapy rather than BSC. This retrospective analysis included 140 consecutive patients managed in a rural region of Norway (2007-2022). Two differently managed groups were compared in univariate tests followed by multi-nominal regression. The majority of patients (n=95, 68%) had received systemic therapy. Typical patients were males in their 60s or 70s, with clear cell histology, prior nephrectomy, and intermediate prognostic features. Patients who received systemic therapy lived significantly longer than those who did not (median 30.4 versus 5.0 months, p<0.001). Survival benefit of systemic treatment was observed even in patients with ECOG PS3 or age ≥80 years. In addition to younger age (p<0.001) and better ECOG PS (p<0.001), metachronous presentation was associated with higher rates of systemic therapy utilization (p=0.03). Assignment to systemic therapy for mRCC was individualized in the present patient population. In all age and ECOG PS subgroups, systemic therapy was associated with better survival (doubling at least). Optimum utilization rates are difficult to determine. However, in light of the survival outcomes, a rate of 12% in patients aged 80 years or older appears rather low.

LC-qTOF-MS/MS phytochemical profiling of Tabebuia impetiginosa (Mart. Ex DC.) Standl. leaf and assessment of its neuroprotective potential in rats

Ethnopharmacological relevanceTabebuia impetiginosa (Bignoniaceae) was traditionally used for memory enhancement and central nervous system (CNS) stimulation.Aim of the study: This study aims to create a metabolic profile of the ethyl acetate fraction of T. impetiginosa (TEF) and investigate for the first time its neuroprotective potential on cyclophosphamide (CP)-induced chemobrain, validating its traditional use. Materials and methodsMetabolite profiling of TEF was performed using Liquid Chromatography coupled with Quadrupole Time of Flight-Mass/Mass Spectrometry (LC-qTOF-MS/MS). For the in vivo study, CP (200 mg/kg, i.p.) was administered to induce cognitive impairment in rats; TEF (30 mg/kg, p.o.) was administered throughout the 14 days of the experiment to assess its role in mitigating CP-induced neuronal deficits. Behavioral tests including locomotor, Y-maze, and passive avoidance tests were conducted. Additionally, biochemical markers such as reduced glutathione (GSH), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), and caspase-3 immunoexpression were assessed in the hippocampus area. ResultsForty-four phytoconstituents were tentatively identified in TEF, mainly iridoids and organic acids. TEF showed significant memory enhancement as evidenced by the increase in step-through latency in the passive avoidance test by 1.5 folds and the increase in sequence alternation percentage (SAP) in the Y-maze test by 67.3%, as compared to CP-group. Moreover, it showed pronounced antioxidant and anti-inflammatory potentials evidenced by the significant elevation in reduced glutathione (GSH) levels by 80% and a pronounced decline in MDA and TNF-α levels by 24% and 45%, respectively relative to the CP group. TEF treatment restored normal hippocampal histological features and attenuated apoptotic caspase-3 expression by 70% compared to the CP group. ConclusionsTEF can act as a promising natural scaffold in managing the chemobrain induced by CP in cancer patients.

Abstract PO4-26-02: Evaluation of Tumor Infiltrating Lymphocytes as a predictive biomarker of recurrence in patients with Ductal Carcinoma In Situ of the breast

Abstract Introduction: Ductal carcinoma in situ (DCIS) represents around 20% of early breast cancer diagnoses globally. Some studies evaluated risk factors associated with DCIS recurrence. Among these, age, surgical margins, comedonecrosis (CN), high nuclear grade, negative hormone receptors and HER2 expression stand out. Recent approaches have been evaluating the role of the immune microenvironment and its association with recurrence and progression of DCIS. Objective: To evaluate the association between Tumor Infiltrating Lymphocytes (TILs) in DCIS samples and disease recurrence. To characterize the immunological microenvironment of DCIS, analyzing the presence of TILs, “touching TILs” and desmoplastic reaction and their association with recurrence. Epidemiological, clinical, histological and immunohistochemical (IHC) characteristics were also evaluated. Methods: This is a retrospective cohort study with patients diagnosed with DCIS and treated at Sao Paulo State Cancer Institute and Hospital das Clinicas of University of Sao Paulo. We included women over 18 years old with a diagnosis of DCIS who underwent treatment from Jan/2007 to Dec/2020. Male patients, patients with a diagnosis of invasive or microinvasive disease in the anatomopathological examination of the surgical specimen or patients with history of any neoplasm were excluded. The main outcome was survival analysis according to the quantification of TILs, adjusted for potential confounders. For that, we collected data on age, presence of palpable mass, imaging findings, histological and IHC characteristics, such as expression of estrogen receptor (ER), progesterone receptor (PR) and hyperexpression of HER2, type of surgical approach, type of radiation therapy, use of endocrine therapy, length of follow-up, recurrence, and its type. Two pathologists evaluated TILS in the sample with the highest tumor representation and numerically quantified it as percentage. They also evaluated the presence of “touching tils” (lymphocytes in contact with the basement membrane) and desmoplastic reaction in the tumor stroma. Kaplan-Meier curves, log-rank tests and Cox regression models were used to evaluate survival. Chi-square tests were used to evaluate the association between categorical variables. Results: 283 patients met the eligibility criteria. Mean age of patients was 55 years. 15% had a palpable nodule at physical examination. Clustered amorphous microcalcifications were the most prevalent mammographic presentation, found in 41% of the patients. The most frequent histological and IHC features were cribriform presentation (73%) and ER positivity (86%), respectively. Desmoplastic reaction was absent in 10.5%, discreet in 51.9%, moderate in 24% and intense in 13.6% of the patients. Breast conserving surgery was performed in 189 patients, and 100 of them received adjuvant radiation therapy. Mean follow-up was 77.2 months, with a recurrence rate of 9.2%. We observed that tumors with focal necrosis (HR 6.4 [1.39-34.71] p 0.018) or CN (HR 4.53 [1.34 – 15.28] p 0.015) had higher risks of recurrence. Patients with a percentage value of TILs greater than or equal to 17% also had a higher risks of recurrence (HR 2.97 (1.17-7.51) p 0.02). These patients were mostly under 65 years of age (OR 0.45 [0.21 - 0.97] p 0.049). In a multivariate model, CN and TILs&amp;gt;17% remained significantly associated with recurrence (p=0.034 and p=0.035 respectively). There was a trend for invasive recurrence in 76.9% of the patients that relapsed when TILS were greater than or equal to 17% (p 0.062). “Touching TILs” were present in 12.9% of the patients but were not associated with recurrence (p=0.575). Conclusion: In our cohort, high value of TILs (&amp;gt;= 17%) and presence of CN were independently associated with DCIS recurrence. Our findings suggest that TILS are a prognostic immunological biomarker in DCIS and warrant further investigation in prospective trials to determine the most adequate cut-point. Citation Format: Camila Pasetto, Fernando Aguiar, Marcella Peixoto, Maira Doria, Bruna Mota, Jonathan Maesaka, Jose Roberto Filassi, Edmund Baracat, Rodrigo Gonçalves. Evaluation of Tumor Infiltrating Lymphocytes as a predictive biomarker of recurrence in patients with Ductal Carcinoma In Situ of the breast [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-26-02.

Abstract PO3-08-03: Comparing prognosis for BRCA1, BRCA2 and non-BRCA breast cancer

Abstract BACKGROUND Breast Cancer (BC) is the most diagnosed malignancy and the leading cause of cancer death in women worldwide. Approximately 10% of BC cases are hereditary, and up to 25% have been linked to germline variants of specific genes. Germline pathogenic variants (PV) in BRCA1 and BRCA2 genes, which account for 20% of familial BC cases, are highly penetrant and are associated with Hereditary Breast/Ovarian Cancer Syndrome. BRCA1 e BRCA2 are tumor suppressor genes, which interact with recombination/DNA repair proteins in pathways that participate in preserving intact chromosome structure, particularly on the DNA double chain. So far, more than 7000 PV were identified on these genes, including the Portuguese founder mutation (BRCA2 c.156_157insAlu), which accounts for a great proportion of BC cases in our country. BRCA1 and BRCA2 associated BC have distinct clinicopathological characteristics. Long-term follow-up data related to prognosis and survival of either BRCA1 or BRCA2 BC patients is conflicting. Two large meta-analysis report worse overall survival for both, when compared to sporadic BC, whereas two other large meta-analysis concluded on worse overall survival only for BRCA1 patients, with similar overall survival for BRCA2 patients. One meta-analysis reports similar survival for both groups. We report the analysis of our cohort of BRCA1/2 BC patients included in our multidisciplinary program. Our goal is to compare clinicopathological characteristics and prognosis between BRCA1 and BRCA2 BC and with a control group without germline PV (non-BRCA). METHODS Prospective follow-up was proposed to patients with a diagnosed BRCA1/2 PV. This study included BRCA1/2 patients with BC as first cancer diagnosis, observed between January 2000-May 2023. A control group, with similar phenotype and histological characteristics, without germline PV was used. Statistical analysis was performed to compare characteristics and prognosis between BRCA1 and BRCA2 and non-BRCA BC. ANOVA test was used to compare the age at diagnosis; chi-square was used to compare categorical variables, such as histological subtype and clinical staging at diagnosis; log rank was used to compare the primary and secondary endpoints – overall survival (OS) and invasive disease-free survival (iDFS), respectively. RESULTS From 1077 individuals who tested positive for BRCA1/2 PV, 345 patients had BC, mostly with a BRCA2 PV (66.4%). A control group of 339 individuals was assembled. BRCA2 BC was mostly luminal, as non-BRCA patients, compared with BRCA1 (73.8% vs. 65.8% vs. 25.9%, p&amp;lt; 0.001) and BRCA1 was mostly triple negative, compared with non-BRCA and BRCA2 (65.5% vs. 16.5% vs. 13.3%, p&amp;lt; 0.001). For a mean follow-up time of 10.6 years (±5.6), recurrence was similar, with central nervous system (CNS) metastases being more frequent for BRCA1 (66.7% vs. 23.7% in non-BRCA, and vs. 9.1% in BRCA2, p&amp;lt; 0.001), and bone metastases were predominant for BRCA2 BC (57.5% vs 33.3% in non-BRCA, and vs. 9.1% in BRCA1, p=0.003). Non-BRCA BC showed longer time to recurrence (99.3 months vs. 76.5 months in BRCA2 BC, and vs. 61.2 months in BRCA1 BC, p=0.010), although longer OS was observed in BRCA2 BC (136.2 months vs. 121.7 months in BRCA1 BC, and vs. 113.2 months in non-BRCA, p&amp;lt; 0.001). Development of second primary tumors was more frequent in BRCA2 patients, compared with BRCA1 (20.9% vs 9.2%, p=0.002). DISCUSSION In the Portuguese population, BRCA2 BC is more frequent than BRCA1 BC. Relapses occurred later for BRCA2 BC, affecting mostly the bone, whereas BRCA1 BC relapsed in CNS. As it is stated in the literature, BRCA1 BC is consistent with triple negative, as BRCA2 BC is more associated with luminal subtype. Differences in iDFS favored non-BRCA patients, whereas OS was significantly improved in BRCA2 BC patients. This is the biggest cohort presented in the Portuguese population and one of the biggest presenting BRCA2 BC patients. Table 1 Characteristics of patients according to BRCA1/2 mutation status (n = 684) Citation Format: Pedro Antunes Meireles, Catarina Bexiga, Sofia Fragoso, Sidónia Santos, Teresa Duarte, Fátima Vaz. Comparing prognosis for BRCA1, BRCA2 and non-BRCA breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-08-03.

Abstract PO4-20-12: Case Report: Should core needle biopsy showing primary leiomyosarcoma of the breast warrant a second look for accurate diagnosis and management?

Abstract A 68-year-old female with unknown medical history presented to the emergency department with an exceptionally large necrotic mass of the right breast. Initial core needle biopsy showed morphology consistent with the exceedingly rare leiomyosarcoma of the breast. This patient’s necrotic, fungating tumor with abscess warranted urgent surgical excision. The pathology report that followed revealed malignant phyllodes tumor as her final diagnosis. The patient did well after surgery with no sign of metastasis and continued to follow-up with oncology. Lack of clinical guidance for breast leiomyosarcoma begs the question as to when further workup is indicated since it is known to imitate the histological and radiological features of other breast lesions. We discuss the need for updated guidance from prospective future studies to change national guidelines. Citation Format: Amanda Ritter, Sergey Shimunov. Case Report: Should core needle biopsy showing primary leiomyosarcoma of the breast warrant a second look for accurate diagnosis and management? [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-20-12.

Ganglioglioma with anaplastic/high-grade transformation: Histopathologic, molecular, and epigenetic characterization of 3 cases.

Ganglioglioma (GG) with anaplasia (anaplastic ganglioglioma) is a rare and controversial diagnosis. When present, anaplasia involves the glial component of the tumor, either at presentation or at recurrence. To date, most published cases lack molecular characterization. We describe the histologic and molecular features of 3 patients presenting with BRAF p. V600E-mutant GG (CNS WHO grade 1) with high-grade glial transformation at recurrence. The tumors occurred in pediatric patients (age 9-16 years) with time to recurrence from 20 months to 7 years. At presentation, each tumor was low-grade, with a BRAFV600E-positive ganglion cell component and a glial component resembling pleomorphic xanthoastrocytoma (PXA) or fibrillary astrocytoma. At recurrence, tumors resembled anaplastic PXA or high-grade astrocytomas without neuronal differentiation. CDKN2A homozygous deletion (HD) was absent in all primary tumors. At recurrence, 2 cases acquired CDKN2A HD; the third case showed loss of p16 and MTAP immunoexpression, but no CDKN2A/B HD or mutation was identified. By DNA methylation profiling, all primary and recurrent tumors either grouped or definitely matched to different methylation classes. Our findings indicate that malignant progression of the glial component can occur in GG and suggest that CDKN2A/B inactivation plays a significant role in this process.

Abstract PO2-14-08: Development and characterization of breast cancer organoids representing epithelial heterogeneity and drug response

Abstract Organoids serve as an important preclinical model in multiple cancers including breast cancer, demonstrating preservation of biological features and feasibility of drug screening, with reasonable cost and high scalability. It has been reported that patient-derived organoids (PDOs) can be robustly derived from both primary and metastatic breast tumors, with high resemblance to source tissues in histological, genomic, and transcriptomic features, as well as consistency in drug response compared to xeno-transplantations or patients (Sachs et al, 2018). Since 2018, the Institute for Precision Medicine (IPM) has developed a panel of breast cancer organoids. The current inventory now consists of 128 PDOs from 94 primary tumors, 12 metastases, 12 rapid-autopsy tumors, and 10 normal breast tissues with a 60% success rate of culture; as well as 33 organoids from animal models including 11 patient-derived xenograft organoids (PDXOs), 15 rat (RDO) and 7 mouse (MDO) tumor organoids with 85% success rate. For PDOs, the protocol includes in-lab processing of fresh, deidentified tissue within 60 minutes of surgical operation, thanks to close collaboration with surgeons, consented patients, and an institutional biospecimen core. BC organoids have been comprehensively characterized in terms of morphology, histology, genomics, transcriptomics, and functional experiments. Key biological features are preserved. PDOs (n=56) exhibit a mutational spectrum consistent with human breast cancers. ER expression is detectable in a subset of cultures with robust estradiol response indicated by GREB1 expression; and PDOs from invasive lobular carcinoma (ILC) mostly showed more discohesive structures than PDOs from no special type (NST), with clear E-cadherin loss under immunofluorescence. We have also successfully constructed transcriptionally and genetic modified BC PDOs with shRNA and CRISPR, which showed replicable performance in proliferation assay, drug response, and signaling by western blot. Of note, longitudinal tracking of PDOs with single cell RNA-sequencing (scRNA-seq) revealed well-preserved heterogeneity compared to primary tumor, while transcriptomic clonality was mildly decreased in later passages from pilot data. Future work will include expansion of current collection from various sources, longitudinal characterization with scRNA-seq and DNA sequencing, as well as more functional studies. We aim to construct a robust resource of well-characterized and reliably-usable model bank for preclinical breast cancer research. Citation Format: Daniel Brown, Kai Ding, Fangyuan Chen, Jian Chen, Steffi Oesterreich, Peter Lucas, Priscilla McAuliffe, Jennifer Atkinson, ADRIAN LEE. Development and characterization of breast cancer organoids representing epithelial heterogeneity and drug response [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-14-08.

Secretory carcinoma of minor salivary glands.

Secretory carcinoma is a malignant salivary gland tumor, which typically presents as an indolent painless mass within the parotid gland. Involvement of minor gland is reported but less common. Secretory carcinoma was often misclassified as other salivary gland mimics and in particular, acinic cell carcinoma prior to 2010. It was first recognized by Skalova et al. as a molecularly distinct salivary gland tumor harboring the same fusion gene as well as histological and cytogenetic features seen in juvenile breast cancer. Secretory carcinoma is generally managed as other low-grade salivary gland neoplasms and has a favorable prognosis; however, high-grade transformation requiring aggressive therapeutic interventions have been documented. Recent studies of biological agents targeting products of this fusion gene offer the promise of a novel therapeutic option for treatment of this malignancy Due to limited number of reported cases, the spectrum of clinical behavior, best practices for management and long-term treatment outcomes for secretory carcinoma remain unclear. We report a long-standing secretory carcinoma involving minor salivary glands of the mucobuccal fold, which was detected years after it was first noted by the patient. This case brings to light the importance of a thorough clinical exam during dental visits and reviews diagnostic differentiation of this malignancy from other mimics and discusses decision making for its management.

Abstract PO3-15-07: False-negative results of hyperexpression of HER2 receptor in breast cancer at a public tertiary hospital in Brazil

Abstract Introduction: Breast cancer (BC) is the second leading cause of cancer death in women worldwide. One of the major advances in BC management was its molecular classification, especially regarding the Human Epidermal growth factor Receptor 2 (HER2). HER2 positive tumors are at greater risk of visceral metastasis and are associated with worse survival rates. Thus, the use of specific drugs to target this pathway is essential and false-negative have a high impact on patient care. HER2 status is usually accessed using immunohistochemistry (IHC), but false-negatives results occur. When IHC results are inconclusive, in-situ hybridization (ISH) testing is necessary. Objective: to determine if there is variability between the positivity rates between laboratories that performed the ISH, according to the IHQ, and to evaluate if there are false-negative results and possible prognostic impact. Methods: retrospective, observational study in a public hospital in the city of Curitiba (Brazil), followed by cross-sectional analysis of histological samples. All cases of BC that underwent HER2 assessment by IHC and ISH between January 2008 and December 2018 were included. Participants classified as HER2 negative by IHC and patients whose medical records were not available were excluded. A new analysis of all IHC slides and of cases with negative ISH was performed. Results: We identified 205 people with an average age of 53.52 (± 11.89) years. Most cases were classified as clinical stage I and II (68.3%), and the most prevalent histological features were Invasive Ductal Carcinoma (82.4%) and luminal molecular subtype (49.8%). Initial ISH testing was performed by four laboratories. There was a significant difference in HER2 positivity rates between these laboratories, even after individual reanalysis of all IHC slides. Of the 114 cases with negative ISH, it was possible to obtain histological material in 82 of them to perform a new standardized ISH. The false-negative rate for HER2 in this 82 patients was 41.46%, with 10 cases out of 24 for positive IHC (3+) and 22 out of 58 for inconclusive IHC (2+). In this paper, false-negative results did not impact in survival, most likely to differences between groups. Conclusion: our work showed different rates of positivity for HER2 among laboratories that performed confirmatory test with ISH. The performance of a second standardized ISH proved that the difference between the laboratories was due to false-negative results. There was no difference in recurrence and cancer-specific survival in this false-negative sample. Keywords: breast cancer. Biomarkers. Health technology assessment. HER2 receptor. DIfferences between laboratories reagarding HER2 false negatives –insert figrue image– Citation Format: Bruno Batista, Sergio Ioshii, Sergio Padilha, Jacqueline Nabhen, Tayza Ostroski, Caroline Batista. False-negative results of hyperexpression of HER2 receptor in breast cancer at a public tertiary hospital in Brazil [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-15-07.

Micronodular thymic epithelial tumors with lymphoid hyperplasia and mimicking lesions.

Micronodular arrangement of epithelial cells and lymphoid B-cell hyperplasia with follicles are both peculiar histological features in thymic tissue. Such features may especially occur in thymic epithelial tumors. The most common form is called micronodular thymoma with lymphoid stroma. We have recently described some characteristics of thymic micronodular carcinoma with lymphoid hyperplasia, highlighting how this carcinomatous counterpart should not be misdiagnosed as a thymoma. In this review, we discuss these two entities but also other mimics, which may occur in the anterior mediastinum. These mimics include various types of cellular micronodules and lymphoid backgrounds encompassing a wide range of mediastinal lesions. Non-neoplastic lesions, such as thymic nodular epithelial hyperplasia, thymic lymphoid hyperplasia, or sarcoidosis, as well as tumors of very varying aggressiveness, such as micronodular thymic epithelial tumors, low-grade lymphoma, seminoma, or lymphoepithelial carcinoma, are discussed. We show how these lesions may be misleading and we describe how a correct diagnostic may be obtained in current practice.

Abstract PS03-09: Age-related normal breast tissue features differ in women with germline BRCA1/2 mutations

Abstract Ageing, a breast cancer risk factor, can be reflected in histologically normal breast tissue (NBT). However, the relationship between age-related histological features and cancer risk is not fully understood. We propose that biological and microscopic features can be identified in seemingly histologically NBT in gBRCA1/2m carriers that are indicative of the earliest tissue changes of breast cancer, potentially as a result of accelerated tissue ageing. To study NBT, we have put in place a unique and scalable repository, named OASIS, storing currently &amp;gt;2,000 digitised whole slide images (WSI) of H&amp;E-stained NBT from individuals with long clinical follow-up. These tissues are from individuals with a spectrum of risk for developing breast cancer and derived from reduction surgery from non-gBRCA1/2m carriers, risk reducing masectomies, and from contralateral and peri-tumoural NBT from gBRCA1/2m carriers and women with breast cancer. Across 6 NBT resources, 70 selected WSIs were manually annotated for epithelial cells, fibrous stroma and adipocytes, resembling the "ground truth". Extensive comparisons of different tile sizes, tile overlapping ratios, stain normalisation techniques and deep learning (DL) feature extractors were conducted to implement a Tissue-Classifier, which achieved 95% accuracy in 3-fold cross-validation. Based on the MobileNet architecture, a DL-framework achieved a sensitivity of 81.2% and specificity of 81.8% (84.7% AUC) in predicting Tissue-Age based on discernible histological patterns in healthy women. In gBRCA1/2m carriers, we discovered features of accelerated tissue ageing (e.g. degree of lobule involution), indicating that the biological NBT age differs from their chronological age. Our DL-based framework robustly captured histological patterns to predict tissue components and age. The global organisation of these patterns showed variations in WSIs of women with different risks of developing breast cancers, which may provide new insights into premalignant alterations in NBT. Citation Format: Anita Grigoriadis, Mario Parreno-Centeno, Siyuan Chen, Gregory Verghese, Esther Lips, Cheryl Gillett, Louise Jones, Sarah Pinder. Age-related normal breast tissue features differ in women with germline BRCA1/2 mutations [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS03-09.

Abstract PO4-16-01: EZH2 is Overexpressed in Invasive Carcinoma and DCIS in both BRCA1 and BRCA2 Mutation Carriers

Abstract Background The transcriptional repressor EZH2 (Polycomb Group Protein Enhancer of Zeste Homologue 2) is overexpressed in multiple neoplasms including breast cancer where it associates with high proliferation, aggressive features and poor prognosis and is of interest as a potential therapeutic target. EZH2 nuclear expression in breast cancer has been shown to correlate specifically with high tumor grade and basal-like histologic features but has not been well studied in cancers from BRCA carriers. Here we evaluate the expression of EZH2 protein in BRCA-associated invasive breast carcinomas and precursor lesions. Methods Eighteen cases of invasive breast cancer in consented BRCA carriers (8 BRCA1 and 10 BRCA2) treated at Dana Farber Cancer Institute from 2001-2019 were reviewed by two pathologists (TAD and RBPP). Histopathologic features (histologic subtype, nuclear grade, mitotic score) and presence of precursor lesions were recorded. Immunohistochemistry for EZH2 was performed on freshly cut formalin-fixed paraffin-embedded tissue sections (1-3 sections/case) using a monoclonal antibody against EZH2 (D2C9, Cell Signaling). Nuclear EZH2 expression was scored as negative (score=1, no staining); weak (score 2, &amp;lt; 25%); moderate (score=3, 25–75%); and strong (score=4, &amp;gt;75%), of any intensity following published criteria. EZH2 overexpression was defined as scores 3 and 4. Results The majority of the invasive carcinomas showed grade III histology (13/18, 72%), as expected. Of 8 BRCA1 cases, 6 were classified as grade III (75%), 1 as grade II, and 1 as grade I (7 cases of invasive ductal carcinoma and 1 case of invasive tubular carcinoma). Of 10 BRCA2 cases, 7 were classified as grade III (70%) and 3 as grade II (30%) (5 cases of invasive ductal carcinoma and 5 cases of invasive carcinoma with ductal and lobular features). The majority of cases (13 of 18, 72%) showed high expression of EZH2 in the invasive carcinoma (6 BRCA1 and 7 BRCA2 cases; 2 grade II and 11 grade III). Of 13 cases with EZH2 overexpression, 6 were ER+/PR+/HER2- and 7 were triple negative, with 9 invasive ductal carcinomas and 4 invasive carcinomas with ductal and lobular features. Of 5 cases with no/low EZH2 overexpression, 1 was ER+/PR+/HER2-, 3 were ER+/PR-/HER2- and 1 was triple negative, with 3 invasive ductal carcinomas, 1 invasive carcinoma with ductal and lobular features and 1 invasive tubular carcinoma. In all cases with adjacent ductal carcinoma in situ (DCIS) (n=14), the pattern of EZH2 expression in the DCIS was identical to that seen in the invasive carcinoma (11 high and 3 low expression). Overexpression of EZH2 was not observed in any other precursor lesions (LCIS, ADH, ALH) or in normal tissue. Conclusion EZH2 protein overexpression is seen in the majority of invasive carcinomas in BRCA carriers, both in BRCA1 and in BRCA2. In all cases, the associated DCIS shows the same pattern of expression as the invasive carcinoma, suggesting that overexpression occurs early in tumorigenesis, while tumor cells are still confined within the ducts. The high rate of overexpression of EZH2 in BRCA1- and BRCA2-associated tumors suggests a potential role for EZH2 as a target and/or a biomarker in these cancers. Citation Format: Tabata Alves Domingos, Roberto Bonfim Pimenta Peixoto, Rodrigo Fonseca Abreu, Ashka Patel, Krishan Taneja, McKenna Moore, Celina Kleer, Deborah Dillon. EZH2 is Overexpressed in Invasive Carcinoma and DCIS in both BRCA1 and BRCA2 Mutation Carriers [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-16-01.

Abstract GS03-04: Novel Mechanisms of CDH1 Inactivation in Breast Invasive Lobular Carcinoma Unveiled by the Integration of Artificial Intelligence and Genomics

Abstract Background: Invasive lobular carcinoma (ILC) of the breast is the second most common histologic subtype of breast cancer (BC), following invasive ductal carcinoma of no special type (IDC-NST). The hallmark histologic feature of ILC is cellular discohesiveness, the result of bi-allelic inactivation of CDH1, and represents an important genotypic-phenotypic correlation in BC. Although most ILCs harbor CDH1 loss-of function mutations associated to loss-of-heterozygosity (LOH) of the wild type-allele, a subset of ILCs lack these alterations despite displaying a typical lobular phenotype. Here, we sought to identify alternative molecular mechanisms converging on CDH1 inactivation by employing an integrative artificial intelligence (AI) and genomics approach. Materials and Methods: A genomics-driven AI-based algorithm using hematoxylin and eosin (H&amp;E) whole slide images (WSIs) as input, previously developed to detect bi-allelic CDH1 mutations (inactivating mutation associated to LOH) in BC was employed. WSIs of 1,057 BCs including ILCs (n=187) and non-lobular BCs (n=870) previously subjected to FDA-cleared tumor/normal targeted sequencing were subjected to analysis with the AI-based algorithm. Cases predicted to harbor CDH1 bi-allelic mutations by the AI-model but lacking CDH1 bi-allelic mutations by targeted sequencing were assessed through targeted sequencing data re-analysis, CDH1 gene promoter methylation evaluation and/or whole genome sequencing analysis. Results: AI-based analysis WSIs corresponding to 1,057 BCs resulted in the identification of 34 cases found to lack CDH1 bi-allelic mutations by targeted sequencing but predicted to harbor these genetic alterations by the AI-based model. CDH1 gene promoter methylation assessment revealed CDH1 promoter methylation in 18 cases. Targeted sequencing data reanalysis revealed other genetic mechanisms of CDH1 inactivation including CDH1 homozygous deletions (n=3), intragenic deletion with LOH (n=1), and likely pathogenic non-coding CDH1 alterations associated with LOH (n=2). WGS analysis of an ILC revealed a novel deleterious CDH1 fusion stemming from translocation t(13;16), resulting in loss of the 5’UTR, transcription start site and exons 1 and 2 of CDH1, associated with complete loss of E-cadherin protein expression. Taken together, we identified alternative/novel mechanisms of bi-allelic CDH1inactivation in 74% (25/34) cases analyzed. Conclusions: By applying an AI-based algorithm trained to detect a genetic alteration (i.e., CDH1 bi-allelic mutations), we were able to identify alternative epigenetic and genetic molecular mechanisms of CDH1 inactivation in ILCs, including novel non-coding CDH1 genetic alterations and a new inactivating CDH1 fusion gene. These findings indicate that molecular mechanisms affecting a single gene or process converging on the same phenotype can be unveiled by the integration of AI and genomics, highlighting the robustness of this approach for the discovery of novel biology. Citation Format: Fresia Pareja, Higinio Dopeso, Yikan Wang, Andrea Gazzo, David Brown, Pier Selenica, Jan Bernhard, Fatemeh Derakhshan, Edaise M. da Silva, Lorraine Colon-Cartagena, Thais Basili, Antonio Marra, Jillian Sue, Qiqi Ye, Arnaud Da Cruz Paula, Selma Yeni, Xin Pei, Hunter Green, Kaitlyn Gill, Yingjie Zhu, Matthew Lee, Ran Godrich, Adam Casson, Britta Weigelt, Nadeem Riaz, Hanna Y Wen, Edi Brogi, Matthew Hanna, Diana Mandelker, Jeremy Kunz, Brandon Rothrock, Sarat Chandarlapaty, Christopher Kanan, Gerard Oakley III, David Klimstra, Thomas Fuchs, Jorge Reis-Filho. Novel Mechanisms of CDH1 Inactivation in Breast Invasive Lobular Carcinoma Unveiled by the Integration of Artificial Intelligence and Genomics [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr GS03-04.

Abstract PO1-07-01: Artificial intelligence-based prediction of Oncotype DX Score from whole slide images using human-interpretable features and breast biomarkers

Abstract Background The Oncotype DX Breast Recurrence Score assay (ODX) is a commonly used genomic test for patients with estrogen receptor (ER)-positive, HER2-negative, early-stage invasive breast cancer. While ODX predicts patients’ recurrence risk and benefit from chemotherapy, it is tissue and time-consuming, and expensive. Previous deep-learning or non-linear ODX prediction models achieved promising performance using whole-slide images (WSI) or with other covariates (e.g., ER, progesterone receptor (PR), HER-2, Ki-67 scores and tumor stage) but systematic quantification of the contribution of individual histological features to the ODX score remained challenging. Here, we extracted a rich set of human-interpretable features (HIFs) quantifying nuclear morphology and the distribution of cells and tissues in the tumor microenvironment. We used these HIFs, along with manually assessed ER, PR, HER-2 scores, and tumor stage, to predict ODX scores. We also explored the role of Ki-67 features in augmenting our model predictions Methods We developed machine learning models to extract cell, tissue, and nuclear HIFs from WSI stained with hematoxylin and eosin (H&amp;E) and immunohistochemistry (IHC) against Ki-67. These models were deployed on 353 H&amp;E WSI to extract 276 HIFs quantifying cell densities, tissue areas, relative cell counts, and nuclei size, shape and color. Hierarchical agglomerative clustering was applied to cluster these features into 11 groups. Univariate regression was performed to identify correlations between ODX scores and feature clusters. To predict ODX score using HIFs, a multivariable regression model was fitted to the data where regressors are representative features from each cluster, in addition to ER, PR, HER-2 scores and stage as covariates. The model was fitted on the training set (N=266 slides) and evaluated on the held-out test set (N=87 slides). To examine the utility of Ki-67 IHC features in ODX prediction, a Ki-67 model was deployed on a subset of 194 matched Ki-67 IHC WSI to extract count proportions and densities of Ki-67 positive cells in cancer epithelium and stroma. Results Significant positive correlations were identified between ODX scores and feature clusters corresponding to cancer cell density (p &amp;lt; 10-7), macrophage density (p &amp;lt; 10-4), immune cell density (p &amp;lt; 10-16), and variations in cancer nuclear size (p &amp;lt; 10-5) and color (p &amp;lt; 10-3). Significant negative correlations were observed between ODX scores and clusters related to fibroblast density (p &amp;lt; 10-3), and variations of non-cancer cell nuclear color (p = 0.02). Evaluation of our model’s ability to predict ODX scores revealed an association between predicted and observed scores (Pearson r = 0.74). The AUROC for model predictions of high/low classifications (with reference to a cutoff ODX score of 20) was 0.80. Ki-67 features were clustered together with H&amp;E cancer cell density features and showed a stronger correlation with ODX scores compared to the H&amp;E features alone. Combining Ki-67 cell density features with H&amp;E features led to increased performance of the multivariable regression model on the test set compared to H&amp;E features only (r = 0.62 vs. r = 0.59). However, a model combining Ki-67, H&amp;E and covariates performed similarly to a model with H&amp;E and covariates (r = 0.73), suggesting that Ki-67 features may not be needed for ODX prediction when H&amp;E and covariate information is available. Conclusions Our model predicts ODX recurrence scores with comparable performance to other black-box approaches using WSI and breast biomarker status and without the need for, Ki-67 features. Using readily available information, our model has the potential to be a convenient screening tool for patient stratification, which may lead to better patient care, lower costs, and faster treatment. Citation Format: Nhat Le, John Van Arnam, Christian Kirkup, Ylaine Gerardin, Michael Drage, Neha Khaitan, Anurag Sharma, Georgi Galev, Nicholas Indorf, Emily Sansevere, Ilan Wapinski, Stephanie Hennek, Gloria Zhang. Artificial intelligence-based prediction of Oncotype DX Score from whole slide images using human-interpretable features and breast biomarkers [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-07-01.

Abstract PO2-07-05: Deep learning model for automated quantification of HER2 expression in invasive breast cancers from immunohistochemical whole slide images

Abstract Introduction Human epidermal growth factor receptor 2 (HER2) protein overexpression and/or HER2 gene amplification is found in about 20% of invasive breast cancers. Considering the results of the DESTINY-Breast trials confirming the remarkable efficacy of anti-HER2 antibody drug-conjugate (T-Dxd) in both HER2-overexpressed and HER2-low tumors, it is necessary to identify not only HER2 (immunohistochemistry (IHC) score 3+) overexpressing tumors, but also HER2-low tumors. The latter category, defined as IHC1+ or IHC2+ but non-amplified, has proven to be challenging even for experienced pathologists, with high inter-observer variability. Here, we validate the performance of a deep learning (DL) model at: 1) predicting the IHC score from IHC histological features and 2) identifying HER2-low tumors with high sensitivity. Methods 675 HER2 stained IHC slides from primary breast cancer patients were selected based on pathology reports across three different cohorts (KCL_GSTT_1 n=369; Cypath_Breast n=214; KCL_GSTT_2 n=92). The slides were digitized and reviewed by expert breast pathologists. Specifically, Cypath_Breast and KCL_GSTT_2 were each annotated by one expert pathologist, while KCL_GSTT_1 was annotated by 5 expert pathologists with the ground truth defined as a majority vote between the 5 annotators. Cypath_Breast was assigned as the “discovery” set; while KCL_GSTT_1 and KCL_GSTT_2 were used as two independent validation cohorts. The model was specifically trained to extract features from IHC tiles to ensure they would capture both the staining intensity and the staining location on the cells (membrane, cytoplasmic or nuclei). The one-vs-one (OVO) and one-vs-rest (OVR) AUC as well as sensitivity and specificity to HER2-low and positive tumors were used as metrics to assess the performance of our model. An expert pathologist reviewed the most predictive regions of HER2 expression. Results After review by expert pathologists, 59 slides from KCL_GSTT_1 were removed either because of folded tissue, blurriness or because there was too little tissue. The IHC scores (0/1+/2+/3+) for the 3 cohorts were distributed as follows; Cypath_Breast: 42/120/36/16; KCL_GSTT_1: 120/90/52/48; KCL_GSTT_2: 54/22/15/1. For KCL_GSTT_1, the average agreement between the 5 expert pathologists amounted to a Cohen’s Kappa score of 0.63. Following training on Cypath_Breast, the performance of the model are presented in An ablation study proved that a feature extractor trained on IHC tiles outperformed an in-house extractor solely trained on H&amp;E tiles (OVO AUC 0.95 vs 0.93 on KCL_GSTT_1; DeLong p&amp;lt; 0.001). Specifically, the model performed best at distinguishing HER2-negative (HER2 IHC 0) from HER2-low and HER2-positive tumors with a sensitivity (0 vs 1+/2+/3+) of 0.95 [0.93 - 0.98] and a specificity (0 vs 1+/2+/3+) of 0.78 [0.72 - 0.84] on KCL_GSTT_1. We observed the same tendency on KCL_GSTT_2 with a sensitivity (0 vs 1+/2+/3+) of 0.97 [0.91 - 1.00] and a specificity of 0.91 [0.83 - 0.98]. More importantly, the DL model reached a Cohen’s Kappa score of 0.72 [0.67 - 0.77] with the ground truth on KCL_GSTT_1, surpassing the average agreement Kappa score between expert pathologists (0.63). The most predictive regions showed cytoplasmic staining in tumor regions. Conclusion Our model provides a path towards a fully automated workflow for identifying up to 95% of breast cancer patients who could potentially benefit from anti-HER2 targeted therapies. Additionally, we show the utility of AI-based tools to minimize discrepancies among pathologists and assist in the diagnostic patient pathway. Table 1: Results of external validation on KCL_GSTT_1 and KCL_GSTT_2 &amp;lt;grpahic&amp;gt; Cohorts OVO AUC OVR AUC IHC 0 OVR AUC IHC 1+ OVR AUC IHC 2+ OVR AUC IHC 3+ KCL_GSTT_1 0.95 0.95 0.80 0.91 0.99 [0.93 - 0.96] [0.94 - 0.95] [0.79 - 0.82] [0.90 - 0.92] [0.99 - 1.00] KCL_GSTT_2 0.92 0.97 0.78 0.84 N/A [0.90 - 0.93] [0.96 - 0.98] [0.76 - 0.81] [0.80 - 0.88] Citation Format: Pierre-Antoine Bannier, Loïc Herpin, Rémy Dubois, Lydwine Van Praet, Charles Maussion, Ellen Amonoo, Anca Mera, Jasmine Timbres, Cheryl Gillett, Elinor Sawyer, Patrycja Gazinska, Piotr Ziolkowski, Roberto Salgado, Sheeba Irshad. Deep learning model for automated quantification of HER2 expression in invasive breast cancers from immunohistochemical whole slide images [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-07-05.

Histopathology and its clinical correlation of liver biopsy in patients with treated autoimmune hepatitis

The diagnosis of autoimmune hepatitis (AIH) relies on well-established criteria encompassing histological, serological, and clinical features. Diagnosing AIH may become challenging when encountering patients who have undergone steroid therapy for other co-existing diseases. Thirty-nine liver biopsies from 25 patients with treated and untreated AIH were classified into three groups: 1) Newly diagnosed untreated biopsies (n = 16); 2) Newly diagnosed partially treated biopsies from patients already on steroid treatment for other co-existing diseases (n = 9); 3) Previously diagnosed biopsies from patients who had undergone complete treatment (n = 14). In the untreated AIH group, at least 50 % of the cases exhibited the following features: at least moderate portal inflammation (81 %), at least moderate lobular inflammation (56 %), ductular reaction (94 %), inflammation gradient from bile duct to interface (88 %), unequivocal interface hepatitis (100 %), emperipolesis (56 %), plasma cell cluster (88 %), apoptosis or necrosis (63 %), pericentral inflammation (63 %), and periportal fibrosis (88 %). Although all these diagnostically sensitive histologic features were present in significantly fewer cases after treatment (p < 0.05), the features of ductular reaction, inflammation gradient from bile duct to interface, pericentral inflammation, and periportal fibrosis were likely to persist after treatment, especially in partially treated cases; these features did not show a significant association with higher transaminase levels (P > 0.05) and were considered as indirect features of hepatocytic injury. Our data suggest categorizing AIH histological features into direct and indirect hepatocytic injuries. Direct hepatocytic injury features significantly correlate with transaminase levels and respond well to treatment, while indirect ones show weaker transaminase correlation and relative treatment resistance.

Healing activity of a muco-adhesive formula of Teucrium polium against acetic acid-induced oral ulcer in rats

Oral ulcers are highly common painful conditions that harmfully affect the quality of life and require long-term therapy. Muco-adhesive preparations provide efficient and convenient delivery systems that prolong the drug retention time necessary for the different stages of ulcer healing. Therefore, the study aimed to evaluate the healing activity of Teucrium polium in a muco-adhesive formula against acetic acid-induced oral ulcers in rats. Acetic acid was applied to the inner cheeks of the rats and the muco-adhesive formula was applied once daily for 14 days. Acetic acid was found to disrupt the oral tissue histological features, increase collagen deposition, induce oxidative stress through increasing malondialdehyde (MDA) levels and decreasing superoxide dismutase and catalase activities, increase the expression of the inflammatory biomarkers, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), cyclooxygenase-2 (COX-2), and decreased hydroxyproline content and the expression of the factors that contribute in wound healing including transforming growth factor-beta1 (TGF-β1), vascular endothelial growth factor receptor 1 (VEGFR1), and platelet-derived growth factor receptor beta (PDGFRβ). However, the daily application of a mucoadhesive formula impregnated with T. polium, significantly restored the regular histological features of the oral tissue, decreased the concentration of MDA, TNF-α, IL-6, and COX-2, increased superoxide dismutase and catalase activities, and restored the expression of TGF-β1, VEGFR1, and PDGFRβ. Therefore, T. polium extract muco-adhesive formula can be considered a potential therapy for chronic oral ulcers.

Clinicopathologic Analysis of Malabsorption Syndrome in a Tertiary Care Center in South India

ABSTRACT Background: Malabsorption syndrome is an umbrella term for manifestations consisting of diarrhea, steatorrhea, malnutrition, unexplained weight loss, persistent or recurrent abdominal pain, and anemia. Celiac disease and Tropical sprue remain the two important causes among many more. Materials and Methods: The objectives of this study were to assess the spectrum of histological features of malabsorption at a tertiary care center and to correlate the clinical, endoscopic, and histological features between the various etiologies. Biopsy specimens of 547 subjects formed the sample for this institutional-based, retrospective research. All subjects who had a clinical diagnosis of malabsorption and underwent subsequent endoscopic evaluation along with biopsy were considered. The hematoxylin and eosin-stained sections were analyzed for villous architecture and intraepithelial lymphocytes (IELs). The histopathological findings were further correlated with the endoscopic findings. Data thus obtained were statistically analyzed using Microsoft Excel for Windows (2010). Results: The mean age of the subjects was 46.65 ± 17.31 years and with 330 males (60.33%) and 217 female (39.63%) subjects. Chronic diarrhea was the major presenting symptom in 95% of the subjects (n = 520). Normal villous architecture was noted in 68.19%, while the remaining cases showed varying degrees of atrophy ranging from mild in 27.61% (n = 151) to moderate in 2.56% (n = 14) to severe in 1.65% (n = 9). IELs were noted in 70.78% of cases. Conclusion: Histopathological findings, when analyzed, showed intraepithelial lymphocytosis as the major diagnosis in 34.19% of cases (n = 187), followed by tropical sprue in 19.56% (n = 107) cases. The pathology was nonspecific in about 13.89% (n = 76).