Panel Of Immunostains Research Articles

Comparison of antigenicity between frozen section vs non-frozen section tissue blocks: An immunohistochemical study of antibodies commonly used in gynecologic pathology.

Frozen section (FS) is a technique widely used intraoperatively to render a preliminary histopathologic diagnosis, allowing for immediate decisions at the time of surgery. We aimed to investigate potential variations in tissue antigenicity induced by rapid freezing in a variety of gynecologic tumor samples. A total of 177 FS and 177 non-frozen section (NFS) tissue slides were tested using a panel of immunostains commonly used in gynecologic pathology, including hormone receptors (estrogen receptor, progesterone receptor), HER2, mismatch repair proteins (MSH6, PMS2), programmed cell death 1 ligand 1 (PD-L1), p53, napsin A, and ɑ-methylacyl coenzyme-A racemase. Immunohistochemistry results were categorized as positive or negative, and positive cases were subsequently scored based on the distribution and intensity of the staining. Certain immunostains, such as HER2, PD-L1, and p53, were scored according to the established guidelines. The overall concordance between FS and NFS blocks was 87%; among the 13% of discrepant cases, most (10.7%) were classified as minor, with only quantitative differences without foreseeable clinical significance. In 2.3% of cases, there were major qualitative changes with potential impact on disease management. We concluded that FS tissue blocks may, in most cases, safely be used for immunohistochemical studies because most discrepant cases showed only minor differences in staining, with no anticipated clinical significance. Nevertheless, for certain markers, including HER2, p53, and PMS2, a NFS block is preferred when that option is available.

Acute sleep deprivation in mice generates protein pathology consistent with neurodegenerative diseases.

Insufficient or disturbed sleep is strongly associated with adverse health conditions, including various neurodegenerative disorders. While the relationship between sleep and neurodegenerative disease is likely bidirectional, sleep disturbances often predate the onset of other hallmark clinical symptoms. Neuronal waste clearance is significantly more efficient during sleep; thus, disturbed sleep may lead to the accumulation of neuronal proteins that underlie neurodegenerative diseases. Key pathological features of neurodegenerative diseases include an accumulation of misfolded or misprocessed variants of amyloid beta (Aβ), tau, alpha synuclein (α-syn), and TarDNA binding protein 43 (TDP-43). While the presence of fibrillar protein aggregates of these neuronal proteins are characteristic of neurodegenerative diseases, the presence of small soluble toxic oligomeric variants of these different proteins likely precedes the formation of the hallmark aggregates. We hypothesized that sleep deprivation would lead to accumulation of toxic oligomeric variants of Aβ, tau, α-syn, and TDP-43 in brain tissue of wild-type mice. Adult mice were subjected to 6 h of sleep deprivation (zeitgeber 0-6) for 5 consecutive days or were left undisturbed as controls. Following sleep deprivation, brains were collected, and protein pathology was assessed in multiple brain regions using an immunostain panel of reagents selectively targeting neurodegenerative disease-related variants of Aβ, tau, α-syn, and TDP-43. Overall, sleep deprivation elevated levels of all protein variants in at least one of the brain regions of interest. The reagent PDTDP, targeting a TDP-43 variant present in Parkinson's disease, was elevated throughout the brain. The cortex, caudoputamen, and corpus callosum brain regions showed the highest accumulation of pathology following sleep deprivation. These data provide a direct mechanistic link between sleep deprivation, and the hallmark protein pathologies of neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases.

Clear cell adenocarcinoma of the cervix and its mimickers - A series of 19 cases from a tertiary care referral centre in India.

Clear cell adenocarcinoma (CCAC) of cervix is a rare subtype of endocervical adenocarcinoma that accounts for 4% of all cervical adenocarcinoma with many morphological mimickers. Retrospectively study cases of cervical clear cell adenocarcinoma of the cervix. Clinical profile and pathological features of CCAC of the cervix diagnosed between 2018-2022 were retrospectively analyzed.The database of the Department of Pathology of our institute was systematically searched for patients diagnosed with clear cell adenocarcinoma of the cervix during 2018-2022.A total of 19 patients were studied with the mean age of patients being 53.72 years (range 25 -84 yrs,standard deviation-25.9) and median tumor size being 5.6cm. Lymph node metastasis was identified in 33.3% and distant metastasis were seen in 20% of the cases. Staging could not be done in 4 cases.FIGO staging of the cases included IB1(2 cases), IB2(2 cases), IIB (3 cases),IIIA (1 case)IIIB(4 cases),and IV(3 cases). On histopathological evaluation, heterogeneous architectural pattern comprising of tubulocystic, solid, and papillary patterns were seen in 13 cases (13/19,68.4%). Pure tubulocystic (3/19,15.7%), pure papillary (2/19,10.5%), and pure solid patterns (1/19,5.3%) were also identified. Tumor cells with clear cytoplasm ranged from 5% to 95%. Nuclear atypia was moderate to marked in all the cases (19/19,100%). Mitotic activity varied from 1/10hpf to 20-22/10hpf. By immunohistochemistry, tumor was positive for Napsin A in all the cases,p16INK4a was negative in majority of cases (15/19,78.9%) and ER was negative in 14 cases (14/19,73.7%) .p53 showed wild type staining except for one case . Clear cell adenocarcinoma being a rare subtype of cervical adenocarcinoma, needs to be differentiated from other Human Papilloma Virus(HPV) independent adenocarcinomas (gastric and mesonephric types) and benign entities such as endocervical glandular Arias-Stella reaction. Judicious use of a panel of immunostains is often helpful.

Abstract 636: Coculture model for investigating cellular interactions between colorectal tumor organoids and cancer-associated fibroblasts

Abstract The tumor microenvironment (TME) is well recognized for its role in tumor progression, chemoresistance, and recurrence. The TME consists of various components, such as extracellular matrix (ECM), chemical and mechanical cues, as well as stromal cells and their interactions. As the most abundant cells in tumor stroma, cancer-associated fibroblasts (CAFs) have drawn a lot of attention. It has been reported that CAFs not only directly interact with cancer cells via surface proteins and cytokines, but also influence their behaviors by remodeling the ECM. However, due to their heterogenous characteristics and diverse functions, the influence of tumor-CAF interactions on drug response is not fully understood. Here, we present a coculture model for investigating CAF effects on patient-derived colorectal tumor organoids (CTOs) growth, differentiation, and drug response. It consists of normal colon fibroblasts, CCD18-Co, or patient-derived CAFs seeded with CTOs in a mixed hydrogel containing 90% basement membrane extract (BME) and 10% collagen type I. Media conditions were optimized (1:1 mix of CTO culture media plus reduced media excluding growth factors and inhibitors) to achieve similar organoid sizes in the monoculture and coculture conditions at the onset of drug testing. To support higher throughput investigations, our workflow incorporates a liquid handler for automated CTO seeding, media and drug exchange, and an automated microscope with a robotic arm for multi-plate imaging. Briefly, single cell CTOs and fibroblasts were seeded at a 1:1 ratio (3000 total cells/well) in 96-well plates. After 4 days in culture, anti-cancer drugs were administrated in reduced media to the samples. Brightfield images were acquired on days 0, 3, and 5 after drug administration. The collected images were analyzed with a neural network (NN) to dynamically monitor the growth and viability of individual organoids. The CellTiter-Glo assay was performed on day 5 to quantify the total CTO cell viability. The normalized drug response (NDR) was calculated from the NN processed images to determine the drug response. An immunostaining panel, which includes protein markers such as CK20, Ki67, α-SMA, Vimentin, and FAP, was used to evaluate the fibroblast phenotypes and CTO differentiation. Additionally, the cultures were subjected to fluorescent lifetime imaging microscopy (FLIM), a label-free imaging technique, to measure the metabolic adaptations of each cell population. Preliminary studies revealed a CAF-dependent increase in CTO growth and glycolytic signatures in the co-culture setting; however, minimal effects on drug response to common chemotherapy agents such as 5-fluorouracil and irinotecan were observed. In the future, we will use this integrated pipeline as a screening method to identify new treatment strategies aimed at targeting the stromal microenvironment in colorectal cancer. Citation Format: Yuyuan Zhou, Yu-Kai Huang, Emma J. Fong, Elizabeth Elton, Erin McManus, Brandon Choi, Seungil Kim, Shannon M. Mumenthaler. Coculture model for investigating cellular interactions between colorectal tumor organoids and cancer-associated fibroblasts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 636.

Traumatic Brain Injury in Mice Generates Early-Stage Alzheimer’s Disease Related Protein Pathology that Correlates with Neurobehavioral Deficits

Traumatic brain injury (TBI) increases the long-term risk of neurodegenerative diseases, including Alzheimer’s disease (AD). Here, we demonstrate that protein variant pathology generated in brain tissue of an experimental TBI mouse model is similar to protein variant pathology observed during early stages of AD, and that subacute accumulation of AD associated variants of amyloid beta (Aβ) and tau in the TBI mouse model correlated with behavioral deficits. Male C57BL/6 mice were subjected to midline fluid percussion injury or to sham injury, after which sensorimotor function (rotarod, neurological severity score), cognitive deficit (novel object recognition), and affective deficits (elevated plus maze, forced swim task) were assessed post-injury (DPI). Protein pathology at 7, 14, and 28 DPI was measured in multiple brain regions using an immunostain panel of reagents selectively targeting different neurodegenerative disease-related variants of Aβ, tau, TDP-43, and alpha-synuclein. Overall, TBI resulted in sensorimotor deficits and accumulation of AD-related protein variant pathology near the impact site, both of which returned to sham levels by 14 DPI. Individual mice, however, showed persistent behavioral deficits and/or accumulation of toxic protein variants at 28 DPI. Behavioral outcomes of each mouse were correlated with levels of seven different protein variants in ten brain regions at specific DPI. Out of 21 significant correlations between protein variant levels and behavioral deficits, 18 were with variants of Aβ or tau. Correlations at 28 DPI were all between a single Aβ or tau variant, both of which are strongly associated with human AD cases. These data provide a direct mechanistic link between protein pathology resulting from TBI and the hallmarks of AD.

Immunohistochemistry in the pathologic diagnosis and management of thyroid neoplasms.

The use of immunohistochemistry cannot be underestimated in the everyday practice of thyroid pathology. It has evolved over the years beyond the traditional confirmation of thyroid origin to molecular profiling and the prediction of clinical behavior. In addition, immunohistochemistry has served to implement changes in the current thyroid tumor classification scheme. It is prudent to perform a panel of immunostains, and the immunoprofile should be interpreted in light of the cytologic and architectural features. Immunohistochemistry can also be easily performed in the limited cellularity specimen preparation generated from thyroid fine-needle aspiration and core biopsy; however, it will require laboratory validation of immunostains specific to these preparations to avoid diagnostic pitfalls. This review discusses the application of immunohistochemistry in thyroid pathology with a focus on limited cellularity preparations.

TRPS1 and GATA3 Expression in Invasive Breast Carcinoma With Apocrine Differentiation.

The recently identified immunohistochemical marker TRPS1 is highly sensitive and specific for invasive breast carcinoma, especially triple-negative breast carcinoma. However, TRPS1 expression in special morphologic subtypes of breast cancer is unclear. To investigate the expression of TRPS1 in invasive breast cancer with apocrine differentiation, in comparison to the expression of GATA3. A total of 52 invasive breast carcinomas with apocrine differentiation, comprising 41 triple-negative breast carcinomas and 11 estrogen receptor (ER) and progesterone receptor (PR)-negative, human epidermal growth factor receptor 2 (HER2)-positive cases, along with 11 triple-negative breast carcinomas without apocrine differentiation, were evaluated for TRPS1 and GATA3 expression by immunohistochemistry. All tumors were diffusely positive (>90%) for androgen receptor (AR). Triple-negative breast carcinoma with apocrine differentiation had positive TRPS1 expression in 12% of cases (5 of 41), whereas GATA3 was positive in all cases. Similarly, HER2+/ER- invasive breast carcinoma with apocrine differentiation showed positive TRPS1 in 18% of cases (2 of 11), whereas GATA3 was positive in all cases. In contrast, triple-negative breast carcinoma with strong AR expression but without apocrine differentiation showed both TRPS1 and GATA3 expression in 100% (11 of 11) of cases. Most ER-/PR-/AR+ invasive breast carcinomas with apocrine differentiation are TRPS1 negative and GATA3 positive, regardless of HER2 status. Therefore, TRPS1 negativity does not exclude breast origin in tumors with apocrine differentiation. A panel of TRPS1 and GATA3 immunostains can be helpful when the tissue origin of such tumors is clinically relevant.

Transcription Factor Immunohistochemistry in the Classification of Pituitary Neuroendocrine Tumor/Adenoma: Proposal in a Limited-Resource Setting.

Pituitary neuroendocrine tumors/adenomas are common intracranial tumors that require accurate subtyping because each tumor differs in its biologic behavior and response to treatment. Pituitary-specific transcription factors allow for improved lineage identification and diagnosis of newly introduced variants. To assess the usefulness of transcription factors and design a limited panel of immunostains for classification of pituitary neuroendocrine tumors/adenoma. A total of 356 tumors were classified as per expression of pituitary hormones and transcription factors T-box family member TBX19 (TPIT), pituitary-specific POU-class homeodomain (PIT1), and steroidogenic factor-1 (SF-1). The resultant classification was correlated with patients' clinical and biochemical features. The performance and relevance of individual immunostains were analyzed. Reclassification of 34.8% (124 of 356) of pituitary neuroendocrine tumors/adenoma was done after application of transcription factors. The highest agreement with final diagnosis was seen using a combination of hormone and transcription factors. SF-1 had higher sensitivity, specificity, and predictive value compared with follicle-stimulating hormone and luteinizing hormone. On the other hand, TPIT and PIT1 had similar performance and Allred scores compared with their respective hormones. SF-1 and PIT1 should be included in the routine panel for guiding the classification. PIT1 positivity needs to be followed by hormone immunohistochemistry, especially in nonfunctional cases. TPIT and adrenocorticotropin can be used interchangeably as per availability of the lab.

Pagetoid Spread in Basal Cell Carcinoma: Potential for Misdiagnosis.

Basal cell carcinomas are one of the most common cutaneous carcinomas and show classical histologic features of basaloid nests with peripheral palisading. Pagetoid and intraepidermal spread has not been described in basal cell carcinoma to the best of our knowledge. We report 5 cases of basal cell carcinoma with classic histologic patterns and overlying basaloid nests and single intraepidermal tumor cells. A panel of immunostains were performed that included CK7, MOC31, CEA-m, EMA, androgen receptor, and Bcl2. Most of our cases were positive for both MOC31 and CK7, and all cases were negative for CEA-m and EMA excluding extramammary Paget disease, one of the most common differential diagnoses. These cases expand the spectrum of findings that can be seen in basal cell carcinoma and can help prevent misdiagnoses of basal cell carcinomas as more aggressive tumors.

Case series of rare primary cardiac sarcomas: A challenging histopathological diagnosis

Primary cardiac sarcomas are rare and histologically diverse, with single tumors able to demonstrate histological heterogeneity. Consequently, they are often misdiagnosed as other common cardiac tumors, such as cardiac myxoma or other metastatic malignancies. Incorrect diagnoses can result in incomplete surgeries, inadequate treatment regimens, and early recurrence. In our experience, based on the diverse histological and cytological characteristics of these tumors, immunostaining panels should be used early on to differentiate the exact tumor type. SMA, CD31, myogenin, ERG, and SOX10 panels are used to identify spindle-shaped or polymorphic cell patterns, while CK, LCA, S100, and desmin panels are used for round and monomorphic cell patterns. Using these panels can help identify the histological type of primary cardiac sarcomas, which is normally a challenge for pathologists.

Pathologic and molecular insights in nodal T-follicular helper cell lymphomas.

T-follicular helper (TFH) cells are one of the T-cell subsets with a critical role in the regulation of germinal center (GC) reactions. TFH cells contribute to the positive selection of GC B-cells and promote plasma cell differentiation and antibody production. TFH cells express a unique phenotype characterized by PD-1hi, ICOShi, CD40Lhi, CD95hi, CTLAhi, CCR7lo, and CXCR5hi . Three main subtypes of nodal TFH lymphomas have been described: 1) angioimmunoblastic-type, 2) follicular-type, and 3) not otherwise specified (NOS). The diagnosis of these neoplasms can be challenging, and it is rendered based on a combination of clinical, laboratory, histopathologic, immunophenotypic, and molecular findings. The markers most frequently used to identify a TFH immunophenotype in paraffin-embedded tissue sections include PD-1, CXCL13, CXCR5, ICOS, BCL6, and CD10. These neoplasms feature a characteristic and similar, but not identical, mutational landscape with mutations in epigenetic modifiers (TET2, DNMT3A, IDH2), RHOA, and T-cell receptor signaling genes. Here, we briefly review the biology of TFH cells and present a summary of the current pathologic, molecular, and genetic features of nodal lymphomas. We want to highlight the importance of performing a consistent panel of TFH immunostains and mutational studies in TCLs to identify TFH lymphomas.

GATA3 expression in primary lung carcinomas: correlation with histopathologic features and TTF-1, napsin A, and p40 expression

This study assessed the expression of GATA3 in primary lung carcinomas and correlated it with tumor histology and immunostains routinely utilized in the work up of primary lung cancers. Tissue microarrays (TMAs) were constructed from a cohort of 184 non-small cell carcinomas, stained with GATA3, p40, TTF-1, and napsin A, and analyzed semi-quantitatively. All TMA cases with GATA3 expression were further analyzed using corresponding whole slide sections. Positive GATA3 staining was present in 16 cases (9%), including 7 squamous cell carcinomas (SqCCs) (4%), 4 adenocarcinomas (AdCs) (2%), 2 adenosquamous carcinomas (AdSqCs) (1%), 2 large cell carcinomas (LCCs) (1%), and 1 sarcomatoid carcinoma (SC) (<1%). Among tumor histotypes, SqCC was more likely to stain with GATA3 (7/49, 14%), while AdC was less likely (4/111, 4%) (p=0.04). In GATA3-positive cases, high-level expression was observed in 9 cases (56%), including 5 p40-positive SqCCs (3 were nonkeratinizing), 1 p40-positive AdSqC (negative for TTF-1 and napsin A), and 1 AdC (solid), 1 LCC, and 1 SC, each negative for p40, TTF-1, and napsin A). Low-level GATA3 expression was found in 3 AdCs (1 was lepidic and 2 were acinar predominant), 2 SqCCs (keratinizing), 1 AdSqC, and 1 LCC. These findings indicate that GATA3 expression occurs in a minor but significant proportion of primary non-small cell lung carcinomas, most often involves SqCC, and tends to show increasing levels of expression in more poorly differentiated subtypes. Caution should be exercised when interpreting GATA3 expression, and a panel of immunostains should be utilized when assigning tumor origin.

Dermatofibromas with Aberrant Expression of CD34 Protein: A Systematic Review and a Reappraisal of Clinicopathological Features and Histogenesis.

Dermatofibromas (DFs) are benign fibrohistiocytic lesions that usually do not express CD34 protein. This study aimed to analyze the literature concerning the immunohistological and ultrastructural features of DFs. It also related these features to the histogenesis of these lesions. This study included a PubMed literature search for studies addressing the clinicopathological, ultrastructural, and immunohistochemical features of DFs. It also presented some current cases of CD34-negative DFs and a subset of these lesions with aberrant expression of this protein. Analysis of the PubMed literature revealed that DFs with an aberrant expression of CD34 are rare tumors that commonly affect the extremities of adult females. Separating these tumors from dermatofibrosarcoma protuberans (DFSP, CD34-positive tumors) requires using a large panel of immunostains. Ultrastructurally, DFs are composed of diverse cell types, including cells with histiocytic, myofibroblastic, and fibroblastic features. An analysis of the DFs described by this study revealed that cases with an aberrant expression of CD34 protein had slightly high mean age and male sex predominance when compared to CD34-negative cases. The former commonly affected the extremities. There was no evidence of local recurrence or distant metastasis on follow-up. DFs have the potential to express CD34 protein, defining a rare aberrant phenotype, which was not associated with any differences in the outcome as compared to CD34-negative DFs.

Germ cell neoplasms of the testis: Update for 2022.

Germ cell neoplasia in situ (GCNIS) is the precursor of both seminomatous and non-seminomatous germ cell tumors. It consists of distended tubules that may have either intratubular seminoma or intratubular embryonal carcinoma cells. Many invasive non-seminomatous tumors contain a mixture of tumor types, which are reviewed here. Morphology, aided by a panel of immunostains, can determine the presence and percent of embryonal carcinoma, yolk sac tumor, choriocarcinoma, or teratoma in such tumors. Use of immunostains, required for diagnosis in perhaps 25% of testicular neoplasms, is reviewed. Changes of classification in the AJCC (8th edition) in 2016 are discussed, including the partitioning of two tumor types: the central role of chromosome 12p amplification allows both teratoma and yolk sac tumor to be divided into prepubertal types (lacking amplification) and post-pubertal types. Occasionally, sex cord-stromal tumors, hematolymphoid tumors, or epididymal adenomatoid tumors enter the differential diagnosis of germ cell neoplasms.

Landscape and age dynamics of immune cells in the Egyptian rousette bat.

Bats harbor high-impact zoonotic viruses often in the absence of disease manifestation. This restriction and disease tolerance possibly rely on specific immunological features. In-depth molecular characterization of cellular immunity and imprinting of age on leukocyte compartments remained unexplored in bats. We employ single-cell RNA sequencing (scRNA-seq) and establish immunostaining panels to characterize the immune cell landscape in juvenile, subadult, and adult Egyptian rousette bats (ERBs). Transcriptomic and flow cytometry data reveal conserved subsets and substantial enrichments of CD79a+ B cells and CD11b+ Tcells in juvenile animals, whereas neutrophils, CD206+ myeloid cells, and CD3+ Tcells dominate as bats reach adulthood. Despite differing frequencies, phagocytosis of circulating and tissue-resident myeloid cells and proliferation of peripheral and splenic lymphocytes are analogous in juvenile and adult ERBs. We provide a comprehensive map of the immune landscape in ERBs and show age-imprinted resilience progression and find that variability in cellular immunity only partly recapitulates mammalian archetypes.

CD117, BAP1, MTAP, and TdT Is a Useful Immunohistochemical Panel to Distinguish Thymoma from Thymic Carcinoma.

Simple SummaryThymic epithelial tumors, including thymomas and thymic carcinomas are malignant neoplasms that occur in the prevascular (anterior) mediastinum. Thymic carcinomas have a worse outcome than thymomas, and, therefore, management and treatment may differ. However, the morphologic distinction between thymomas and thymic carcinomas can be challenging, as has also been shown in reproducibility studies. We aimed to identify immunohistochemical markers that aid in the distinction between thymomas and thymic carcinomas. We found that a panel of CD117 with a cut-off of 10% tumor cell expression, BAP1, mTAP, and TdT was able to predict 88.9% of thymic carcinomas and 77.8% of thymomas (among the studied types A and B3 thymomas and micronodular thymomas with lymphoid stroma). Only a small subset of thymic carcinomas (11.1%) and thymomas (22.2%) could not be predicted with that model.Background: The morphologic distinction between thymic carcinomas and thymomas, specifically types B3, A, and occasionally micronodular thymomas with lymphoid stroma (MNTLS) can be challenging, as has also been shown in interobserver reproducibility studies. Since thymic carcinomas have a worse prognosis than thymomas, the diagnosis is important for patient management and treatment. This study aimed to identify a panel of immunohistochemical (IHC) markers that aid in the distinction between thymomas and thymic carcinomas in routine practice. Materials and Method: Thymic carcinomas, type A and B3 thymomas, and MNTLS were identified in an institutional database of thymic epithelial tumors (TET) (1963–2021). IHC was performed using antibodies against TdT, Glut-1, CD5, CD117, BAP1, and mTAP. Percent tumor cell staining was recorded (Glut-1, CD5, CD117); loss of expression (BAP1, mTAP) was considered if essentially all tumor cells were negative; TdT was recorded as thymocytes present or absent (including rare thymocytes). Results: 81 specimens included 44 thymomas (25 type A, 11 type B3, 8 MNTLS) and 37 thymic carcinomas (including 24 squamous cell carcinomas). Using BAP1, mTAP, CD117 (cut-off, 10%), and TdT, 88.9% of thymic carcinomas (95.7% of squamous cell carcinomas) and 77.8% of thymomas could be predicted. Glut-1 expression was not found to be useful in that distinction. All tumors that expressed CD5 in ≥50% of tumor cells also expressed CD117 in ≥10% of tumor cells. In four carcinomas with homozygous deletion of CDKN2A, mTAP expression was lost in two squamous cell carcinomas and in a subset of tumor cells of an adenocarcinoma and was preserved in a lymphoepithelial carcinoma. Conclusion: A panel of immunostains including BAP1, mTAP, CD117 (using a cut-off of 10% tumor cell expression), and TdT can be useful in the distinction between thymomas and thymic carcinomas, with only a minority of cases being inconclusive.

GLUT3/SLC2A3 Is an Endogenous Marker of Hypoxia in Prostate Cancer Cell Lines and Patient-Derived Xenograft Tumors.

The microenvironment of solid tumors is dynamic and frequently contains pockets of low oxygen levels (hypoxia) surrounded by oxygenated tissue. Indeed, a compromised vasculature is a hallmark of the tumor microenvironment, creating both spatial gradients and temporal variability in oxygen availability. Notably, hypoxia associates with increased metastasis and poor survival in patients. Therefore, to aid therapeutic decisions and better understand hypoxia’s role in cancer progression, it is critical to identify endogenous biomarkers of hypoxia to spatially phenotype oncogenic lesions in human tissue, whether precancerous, benign, or malignant. Here, we characterize the glucose transporter GLUT3/SLC2A3 as a biomarker of hypoxic prostate epithelial cells and prostate tumors. Transcriptomic analyses of non-tumorigenic, immortalized prostate epithelial cells revealed a highly significant increase in GLUT3 expression under hypoxia. Additionally, GLUT3 protein increased 2.4-fold in cultured hypoxic prostate cell lines and was upregulated within hypoxic regions of xenograft tumors, including two patient-derived xenografts (PDX). Finally, GLUT3 out-performs other established hypoxia markers; GLUT3 staining in PDX specimens detects 2.6–8.3 times more tumor area compared to a mixture of GLUT1 and CA9 antibodies. Therefore, given the heterogeneous nature of tumors, we propose adding GLUT3 to immunostaining panels when trying to detect hypoxic regions in prostate samples.

The role of cytokeratin 7/20 coordination revisited-Machine learning identifies improved interpretative algorithms for cell block immunohistochemistry in aspirates of metastatic carcinoma.

Fine-needle aspiration (FNA) is a robust diagnostic technique often used for tissue diagnosis of metastatic carcinoma. For interpretation of FNA cytology, cell block immunohistochemistry (IHC) and clinicocytologic parameters are indispensable. In this review of a large cohort, the current report: 1) describes clinicocytologic parameters and immunoprofiles of aspirates of metastatic carcinoma, 2) compares the predictivity of immunostains and classical approaches for IHC interpretation, and 3) describes machine learning-based algorithms for IHC interpretation. Aspirates of metastatic carcinoma that had IHC performed were retrieved. Clinicocytologic parameters, IHC results, the corresponding primary site, and histologic diagnoses were recorded. By using machine learning, decision trees for predicting the primary site were generated, their performance was compared with 2 human-designed algorithms, and the primary site was suggested in the historical diagnosis. In total, 1145 cases were identified. The 6 most populated groups were selected for machine learning and predictive analysis. With IHC input, the decision tree achieved a concordance rate of 94.5% and overall accuracy of 83.6%, which improved to 95.3% and 85.8%, respectively, when clinical data were incorporated and exceeded the human-designed IHC algorithms (P < .001). The historical diagnosis was more accurate unless indeterminate diagnoses were regarded as discordant (P < .001). CDX2 and TTF-1 immunostains had the highest weight in model accuracy, occupied the root of the decision trees, scored higher as features of importance, and outperformed the predictive power of cytokeratins 7 and 20. Cytokeratins 7 and 20 may be superseded in immunostaining panels, including organ-specific immunostains such as CDX2 and TTF-1. Machine learning generates algorithms that surpasses human-designed algorithms but is inferior to expert assessment integrating clinical and cytologic assessment.

Immunofluorescence on Formalin Fixed Paraffin Embedded Renal Tissue Sections: A Retrospective Study

Introduction: Direct Immunofluorescence (DIF)/Routine Immunofluorescence (R-IF) on frozen sections is vital in the work-up of renal diseases. Sometimes, the unfixed sample may not be available for DIF or the sample may be inadequate. Paraffin Immunofluorescence (P-IF) can be used as a salvage technique in these situations. R-IF is more sensitive than P-IF in detecting Immunoglobulins (Ig) and complements. P-IF detects characteristic immunoglobulins and complements in the majority of glomerular diseases. Aim: To evaluate the sensitivity of the P-IF in comparison to the gold standard R-IF in renal biopsies with proliferative and non proliferative glomerular diseases. Materials and Methods: The present study was a retrospective study done on 52 selected cases, at St. John’s Medical College, Bangalore, Karnataka, India, data collected from January to December 2016. Based on the clinical differential diagnoses, light microscopy and R-IF findings; selected panels of immunostains (IgG, IgA, IgM, C3, C1q) were done. Proteinase K was used for enzymatic digestion. Immunofluorescence intensity was scored by two pathologists independently. Any specific pattern of staining of atleast 1+ intensity was considered as positive on P-IF. Sensitivity, specificity and confidence intervals were estimated for P-IF. Results: P-IF was done on a total of 52 selected cases. In this study P-IF showed 100% sensitivity for diagnosis of lupus nephritis, infection related glomerulonephritis, Henoch-Schönlein Purpura (HSP) nephritis and 78% for IgA nephropathy. Overall sensitivity in the diagnoses of common glomerular diseases studied was 90% (95% CI=78.97-96.80, p-value=0.025). It was less sensitive for detecting C3. Conclusion: This retrospective study demonstrated that, P-IF has a good sensitivity for diagnosing common glomerulopathies like IgA nephropathy and lupus nephritis. P-IF is a good adjunct to R-IF testing with 100% specificity.

A Challenging and Rare Case of Metastatic Follicular Dendritic Cell Sarcoma Originating from a Tonsil

Abstract Introduction/Objective Follicular dendritic cell sarcoma (FDCS) is a rare malignant tumor of follicular dendritic cells. Most cases of FDCS are described in lymph nodes, but it can involve extra-nodal locations such as the tonsil. Methods/Case Report We report a case of a 55-year-old male with a 6-month history of a slow growing left neck mass. The patient had a poorly differentiated carcinoma of the left tonsil diagnosed based on morphologic features eight years ago, followed by chemoradiation, and subsequent left tonsillectomy without tumor identified. Imaging reported a 4.0 cm mass in the left neck level III lymph node location. Biopsy of the mass revealed a spindle cell neoplasm. It was difficult to reach a definitive diagnosis despite an extensive work-up. Review of the previous left tonsil biopsy showed a pleomorphic epithelioid cell proliferation. On the radical resection specimen of the left neck mass, a 4.5 cm, tan-gray, fleshy, necrotic mass was present. Microscopically, it demonstrated a neoplasm with spindle cell and epithelioid cell proliferation, with extensive necrosis. A wide panel of immunostains was performed; the tumor cells showed positivity for CD21, CD23, CD35, and focally weak positivity for cytokeratin OSCAR and Synaptophysin. Squamous cell markers were negative. These findings are consistent with FDCS. Further work-up on the original tonsil tumor displayed immunostaining profile of FDCS. This case was consulted with the National Institute of Health (NIH) for confirmation of the diagnosis. Results (if a Case Study enter NA) NA Conclusion Morphologically, FDCS can present with various histologic patterns, which can lead to diagnostic pitfalls, and common confusion with poorly differentiated carcinoma or soft tissue tumors, especially in needle biopsies. Generally, patients present with a prolonged clinical course, with a 50% and 25% chance of recurrence and metastasis respectively, hence the awareness and accurate diagnosis of this entity is important in biopsies of lymph nodes or of extranodal locations such as a tonsil.