Positivity For CD20 Research Articles

Clinicopathologic Effects of Xenogeneic GvHD Induced by Adoptively Transferred Human-Derived T Cells in Severely Immunodeficient Mice

Background: Xenogeneic graft-versus-host disease (xGvHD) is an inevitable confounder of preclinical evaluation of adoptive immunotherapies on tumor-bearing immunodeficient mouse models. This study was designed to appraise the clinical and histopathological effects caused by xGvHD in severely immunodeficient mice considering the T cell dosage. Methods: Fifty NOG mice underwent intraperitoneal injection of three different doses of human-derived total T cells, a high dose of CD8+T cells, or vehicle (as control). Clinical and histopathological status of the study subjects were evaluated and compared according to scoring systems. Results: In mice receiving higher doses of total T cells, the clinical severity of xGvHD was greater. However, recipients of CD8+T cells developed none to mild xGvHD manifestations. Higher doses of T cells were associated with poorer outcomes including premature death and more severe histopathologic damages. Greater CD3+T cell tissue engraftment (immunohistochemical CD3 positivity) was associated with more severe xGvHD-induced histopathological damages. Clinical xGvHD scores were significantly correlated with histopathological xGvHD scores in total and in each tissue. Mice with severe cutaneous symptoms had higher scores of xGvHD-induced histopathologic changes in the skin. Lethargy was associated with higher histopathological scores in the lungs, liver and spleen. Conclusion: In preclinical evaluations, lower doses of T cell-based therapies are associated with milder xGvHD. Development of xGvHD may be averted by the use of CD4+T cell-depleted grafts. Histopathological and clinical scoring systems for evaluating xGvHD are significantly correlated. The lungs and liver are reliable organs for histopathological assessment and scoring of xGvHD.

A Rare Case of Signet Ring Cell Lymphoma and Review of the Literature

Signet ring cell lymphoma (SRCL) is a non-Hodgkin's lymphoma with a very rare variant. Although this morphology is frequently seen in follicular lymphoma, it can also be observed in the group of diffuse large B-cell lymphomas. A seventy-six year old woman with known diagnosis of gastric adenocarcinoma, tubular type, moderately differentiate presented with a mesenteric lymphadenopathy with high FDG uptake (SUVmax: 21.3) in PET/CT during follow-up. A tru-cut biopsy was performed for histopathological diagnosis. Diffuse infiltrative singet ring neoplastic cells showed negativity for PanCK, CK7, CK20, S100, SMA, calretinin and vimentin. The panel was then expanded to include SRCL, a rare variant of lymphoma. Additional immunohistochemical evaluation revealed positivity for CD20, CD19, PAX-5 and Bcl-2. Ki-67 proliferation index was about 80%. CD3, CD30, Myc, Bcl-6, ALK, Cyclin-D1, CD23, CD10, CD21, and MUM-1 were negative. EBER was also negative by chromogen in situ hybridization (CISH). Based on these data, diffuse large B-cell lymphoma (DLBCL) was considered. We herein reported a case of signet ring cell lymphoma discussed its clinical and morphological features with regard to the literature.

Liver Metastasis Masking as Neuroendocrine Carcinoma (NEC) Predates Discovery of Intra/Peri-Thyroid Thymic Carcinoma (ITTC)

Abstract Introduction/Objective Intrathyroidal thymic carcinoma (ITTC) also known as Carcinoma showing Thymus-Like differentiation (CASTLE) is a rare malignancy comprising 0.1 to 0.15% of thyroid cancers. The WHO 5th Edition emphasizes that these tumors may also occur outside the thyroid typically at the lower pole Methods/Case Report Our aim is to show that NEC is a mimic of ITTC; that CD5, c-KIT (CD 117), p40, CK5/6 expression distinguishes ITTC from NEC, and that ITTC may at times express NE markers. Briefly, a 51-year-old man presented with hoarseness left neck mass and a PET avid liver lesion in 2016. Biopsy of the neck and liver masses revealed an infiltrating poorly differentiated “NEC” with similar morphology; positive for p53, chromogranin, and synaptophysin; negative for cam5.2, thyroglobulin, TTF-1, CD20, Pax5, CD3, CD5, S-100, calcitonin, CD56, p16, p63, c-KIT (CD117), AE1/3; and 100% staining for Ki-67. The patient underwent chemotherapy, responded well, remained under surveillance, and was symptom-free in the interim. A new 2.1 x 2.0 cm nodule appeared at the left thyroid lower pole after 6 years. The tumor was positive for CD5, CD117, p40, CK5/6, with > 95% Ki67 expression. Chromogranin, synaptophysin, CD56, thyroglobulin, calponin, TTF1, and Epstein Barr virus were negative and was overall diagnostic of ITTC Results (if a Case Study enter NA) NA Conclusion This shows the diagnostic dilemma of distinguishing ITTC from NEC which may share expression of neuroendocrine (NEC) markers and that positivity for CD5, c-KIT (CD117), p40, and CK5/6 are key diagnostic features of ITTC.

Teratoid hepatoblastoma with small cell undifferentiated histology in polysplenia patient: a case report

Abstract Introduction/Objective Hepatoblastoma (HB) with teratoid is a uncommon variant of mixed epithelial and mesenchymal components. Conversely, HB with small cell undifferentiated (SCUD) is extremely rare, with only nine documented cases showing retained INI-1 expression in the literature. The prognosis of SCUD remains debatable. In this report, we describe the first case of combined teratoid HB with a SCUD component that preserved INI-1 expression with a favorable outcome. Methods/Case Report A 2-year-old girl with polysplenia syndrome presented with a right liver mass detected during ultrasound screening. The alpha fetoprotein levels were significantly elevated to 148,000. MRI revealed a 7.2 cm lesion, staged as Pre-Treatment Extent 2 (PRETEXT) in the right anterior liver. She underwent cholecystectomy and right hepatectomy. Resection specimen revealed a mixed neoplasm comprising epithelial components (fetal and embryonal) and mesenchymal components. Additionally, notable findings include small cell component and teratoid features, characterized by melanin pigment and neuroectodermal elements. All the neoplastic cells showed reactivity with CD34, reticulin, SALL4, beta-catenin, GPC-3, arginase-1, chromogranin, and glutamine synthetase. Notably, the teratoid area only displayed positivity for CD56 and NSE, while vimentin highlighted capillaries, vessels and focally staining small cells. Furthermore, CK19 highlighted the small cell components and the bile ducts in the background liver. Importantly, INI-1 staining was retained in all tumor cells, including the small cell component. Synaptophysin and Prussian blue were negative in all lesional cells. After a 2-year follow-up, no recurrence was observed. Results (if a Case Study enter NA) NA Conclusion This case underscores the diagnostic challenge posed by small cell undifferentiated (SCUD) hepatoblastoma. Moreover, it contributes to the understanding of this rare variant of hepatoblastoma and suggests a potential favorable prognosis associated with retained INI-1 staining in the SCUD component.

A Diagnostic Challenge in the Biopsy of a Mammographic Abnormality

Abstract Introduction/Objective Primary breast marginal zone lymphoma (MZL) is an uncommon subtype of extranodal lymphoma, and its diagnosis presents challenges, particularly in distinguishing it from lymphoplasmacytic lymphoma (LPL). MYD88 L265P mutation has been identified in a subset of marginal zone lymphomas, comprising 6-9% of cases. This genetic alteration further complicates the differentiation between MZL and LPL in breast tumors. We present a case highlighting the diagnostic complexities associated with primary breast MZL. Methods/Case Report A 71-year-old female patient underwent mammographic screening, which revealed a suspicious lesion in her left breast. Subsequent PET scan showed a hypermetabolic area consistent with a primary breast lesion. Biopsy histology exhibited a diffuse atypical lymphoid infiltration with varying proportions of neoplastic lymphocytes. Immunohistochemical analysis revealed positivity for CD20, PAX5, BCL2, CD138, MUM1, and negativity for CD3, CD5, Cyclin D1, CD10, CD23, CD34, BCL6, TDT, CD30, GATA3, and CK AE1/3. Additionally, there was lambda light chain restriction, and the Ki67 proliferation rate index was approximately 50%. Fish analysis indicated abnormal BCL6 gene rearrangement. Molecular genetic testing confirmed the presence of MYD88 mutation with c.794T>C p.L265P. Notably, bone marrow biopsy showed no abnormalities, with normal hematopoiesis. Serum electrophoresis and immunofixation detected an IgM monoclonal protein with lambda light chain specificity. Results (if a Case Study enter NA) NA Conclusion The diagnosis of primary breast MZL was favored over LPL due to the absence of common LPL- associated symptoms such as bone marrow involvement. However, the distinction between these entities remains challenging, underscoring the importance of comprehensive diagnostic approaches integrating histopathology, immunohistochemistry, and molecular genetics. Further research is warranted to enhance diagnostic certainty in such cases, particularly as the management of MZL and LPL becomes increasingly specific with the advent of novel therapeutic agents and ongoing clinical trials.

Near missed aggressive natural killer cell leukaemia – importance of extensive immunophenotyping

Aggressive natural killer cell leukaemia (ANKL) is a rare neoplasm of NK cells with poor prognosis, varied morphology and positivity for CD2, CD3 epsilon and CD56, negative for surface CD3 and CD5. A 32-yearold man presented with high grade fever, generalized weakness, significant weight loss in the last 2 months and a lower limb mass, diagnosed elsewhere as Ewing sarcoma. He initially presented with TLC of 8000/uL which drastically increased to 52000/uL, with presence of atypical lymphoid cells. Bone marrow aspiration and biopsy was performed, bone marrow aspirate showed 44% atypical lymphoid cells that were 1.5 to 2 times the size of red blood cells with scant blue agranular cytoplasm, clumped chromatin and inconspicuous nucleoli, and flow cytometric immunophenotyping showed atypical lymphoid cells that were positive for CD45, CD38 and CD 56 and negative for CD34, CD3, CD4, CD5, CD7, CD8, CD20, CD10, CD19, CD138, kappa and lambda. Since a definitive diagnosis could not be reached on this, IHC on bone marrow biopsy was done, which showed the atypical lymphoid cells to be positive for CD45, CD3, CD2, CD56, CD38 and negative for CD117, CD5, CD7, CD30, CD20, CD57 and EBV. A diagnosis of aggressive natural killer lymphoma was reached. The diagnosis was difficult as the morphology and flow cytometry did not show any specific features of ANKL. The diagnosis was made after extensive immunophenotyping on bone marrow biopsy. This highlights the importance of doing NK cell markers when basic panel of antibodies are not supportive.

Clinicopathological differences between T-lymphoblastic leukemia/lymphoma, early T-precursor lymphoblastic leukemia/lymphoma, and mixed-phenotype acute leukemia with T lineage: An analysis of 41 adult cases

The histopathological diagnosis of T-lymphoblastic leukemia/lymphoma, NOS (T-ALL), is based on morphology and positivity for CD3 and TdT. Early T-precursor lymphoblastic leukemia/lymphoma (ETP-ALL) and mixed-phenotype acute leukemia (MPAL), T/M, and/or B rarely occur and are usually diagnosed using flow cytometry. Using only formalin-fixed paraffin-embedded tissue raises the risk of misdiagnosis due to underestimation. Immunostaining markers for T cell (CD1a, CD4, CD5, CD8), B cell (CD19, CD10, CD22, CD79a), and stem/myeloid-related cell (CD33, CD34, CD117, MPO, lysozyme) diagnosed 25 T-ALL cases (61%), 7 MPAL (17%), 6 ETP-ALL (15%), and 3 near ETP-ALL (7%), with subsequent analysis of their clinicopathological characteristics. Patients with MPAL had significantly poorer 2-year progression-free survival (14.3% vs. 60.4%, P = 0.012) and 5-year overall survival (28.6% vs. 65.9%, P = 0.011) than did those with T-ALL, whereas ETP-ALL and near ETP-ALL did not. Of the seven patients with MPAL, three were classified as T/B, two as T/M, and two as T/M/B. Because most MPALs (6/7) share the ETP-ALL phenotype, immunohistochemistry for CD19 and MPO should be performed to avoid misdiagnosing MPAL as ETP-ALL. All three patients with TdT-negative MPAL died of the disease. Four patients with MPO-positive MPAL relapsed during the early phase (1–9 months). Five patients received the ALL regimen, but two patients received acute myeloid leukemia and lymphoma regimens, respectively. In this study, MPAL exhibited a poorer prognosis compared to T-ALL, unlike ETP-ALL. Thus, immunohistochemical classification with multiple antibody panels is useful for accurate diagnosis and treatment.

Abstract B092: Development of predictive models for expression of a tumor specific biomarker and CD3 on H&E digital slides

Abstract Characterization of a patient’s tumor microenvironment is fundamental to advancing translational strategies in immuno-oncology. Histopathological evaluation of tissue slides from patients can provide this invaluable information, informing disease heterogeneity, tumor contexture, and target expression - all important to identifying patients more likely to benefit from therapy. However, availability of sufficient tissue is often a challenge to produce such a comprehensive tumor characterization. Measurement of target expression using an H&E slide could greatly reduce the usage of tissue for IHC making sections available for other investigative purposes. Here, an AI-driven predictive model was developed on H&E digital slides to simulate the expression of a tumor specific biomarker and CD3 across 4 different tumor types. Four epithelial tumor types (TNBC, NSCLC, ovarian, and cervical cancer) consisted of 400 H&E slides, 400 CD3 slides and 400 tumor specific biomarker IHC slides (100 cases per tumor) were used for this study. The Bio-AI Predict-X platform was utilized for the optimization of separate tumor models using pathology annotations as basis for development. The network output included tumor tiles as well as the tiles from adjacent stromal/normal tissue. Models were optimized until an AUC > 0.8 was achieved and prediction results were approved by the combined pathology teams. Predict-X was used for IHC marker quantification on a tile basis for both CD3 and the tumor specific biomarker slides with significant correlation to manual counts (p<0.001, r>0.8). Images from each case were co-registered so that ground truth for each tile with the IHC count was used in the predictive model. Tiles from tumor and corresponding adjacent stroma/normal tissue from all cases were subdivided into 3 groups for predictive model development. A training, validation, and test set were used, the latter of which was not used for development, only as a final assessment of model performance. A pan-tumor predictive model was developed for CD3 IHC on TNBC, cervical and ovarian cancers. The test set AUC values on cases from all 4 tumors were >0.7. Since the tumor specific biomarker stain was specific to tumor morphology, 4 separate predictive models were developed - one for each of the indications used with a test AUC >0.86. These findings suggest that deep learning can be used as a complementary method to prescreen H&E-stained images to enhance the detection rate of the tumor specific biomarker and CD3 positivity in patient tumors. Additional work will involve the optimization of these models for implementation in a clinical setting. Citation Format: Alan Jerusalmi, Krishna Bairavi, Ayushi Shah, Tom Chittenden, Mike Bonham, Chung-Wein Lee, Brandon Higgs, Anantharaman Muthuswamy. Development of predictive models for expression of a tumor specific biomarker and CD3 on H&E digital slides [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B092.

Lymphoma presenting as the first finding in pleural fluid cytology: A rare cytologic presentation

Malignant hemato-lymphoid neoplasms presenting as the initial finding in pleural effusion cytology is one of the rare challenges a pathologist may encounter in practice among lymphocyte-rich effusions. Meanwhile, effusion cytology is an easily available, inexpensive diagnostic tool in our setting. Cytomorphological features provide crucial insights into the nature of the disease, which along with immunocytochemistry may help in solidifying the diagnosis. Here we present a rare case of a 17-year-old patient, who initially presented with pleural effusion that turned out to be lymphoma on cytological examination. Cell blocks were prepared and immunocytochemistry was performed for CD5 and CD23. Tumor cells showed positivity for both CD5 and CD23, confirming the diagnosis of small lymphocytic lymphoma.

The urgency of Burkitt lymphoma diagnosis in fluid cytology-A tertiary care experience.

Burkitt lymphoma (BL) is an aggressive high-grade B-cell non-Hodgkin lymphoma commonly diagnosed in young age and is known to involve extra nodal sites. But the involvement of body fluids by BL is an uncommon presentation. Rapid diagnosis of BL is vital to prevent complications like tumour lysis syndrome. Cytological examination of body fluids continues to be an indispensable tool for rapid diagnosis of BL. In this study, we aim to study the clinical, cytomorphological and immunophenotypic characteristics of BL involving serous effusions and other fluids. In this retrospective study, 17 cases reported as BL in fluid cytology from 2016 to 2022 were collected and reviewed. We performed a comprehensive analysis of the clinical data, cytomorphological features, immunophenotyping data along with the haematological workup of these cases. We have also compared with the histopathological diagnosis for those cases where biopsy was available. BL more commonly involved ascitic fluid (52%), followed by pleural fluid (4 cases) and cerebrospinal fluid (CSF; 4 cases). Primary diagnosis of BL in fluid was done in 88% of the cases. Bone marrow involvement was noted in two cases. Cytological smears showed discrete monomorphous population of medium-sized atypical lymphoid cells with frequent apoptotic bodies. Classic cytoplasmic punched out vacuoles were observed in 88% of the cases. Immunophenotyping data was available for 12 cases in which tumour cells showed positivity for CD20 (100%), CD10 (4 of 7 cases), BCL6 (3 of 5 cases) and cMYC (7 of 7 cases-100%) and were negative for Terminal deoxynucleotidyl transferase (TdT) (11 of 11 cases). Mean Ki67 labelling index was 95%. Histopathological diagnosis was available for 9 cases, and there was 100% agreement between cytological and histopathological diagnosis in 7 cases. Precise diagnosis of BL can be rendered in body fluids by identification of classic cytomorphological features and by performing supportive ancillary tests in fluids for immunophenotyping.

A rare case of EBV-positive gray zone lymphoma

Abstract Introduction/Objective Gray zone lymphoma (GZL) is a rare and novel category of lymphoid neoplasms, first described in 2005. It is derived from B-cells and exhibits characteristics that fall between diffuse large B-cell lymphoma (DLBCL) and classical Hodgkin lymphoma(cHL). Its association with EBV is extremely rare. Here we present one such case Methods/Case Report 80-year-old female presented with progressive neck swelling and significant weight loss for over a month. It was not associated with fever, pain, or night sweats. Her past medical history was significant for hypertension, cerebrovascular accident, breast carcinoma status post-mastectomy, and non-specific B-cell lymphoma on complete remission for 9 years (post rituximab therapy). Complete blood count and metabolic profile were within normal limits. A PET scan revealed hypermetabolic cervical, supraclavicular, right axillary, and mediastinal lymph nodes, suspicious for lymphoma recurrence. The patient underwent an excisional biopsy of the left cervical lymph node which on microscopy showed lymphoid tissue in a nodular pattern with fibrosis and large areas of necrosis. The well-preserved areas showed lymphohistiocytic proliferation composed of large atypical lymphoid cells with prominent nucleoli. An area with increased eosinophils was also noted. Immunohistochemical staining showed strong positivity for EBER, CD30, MUM1, and OCT2 with dim PAX5 positivity. The cells were negative for CD20 and BOB1. Cytogenetics and molecular studies did not reveal any rearrangements or mutations. Flow cytometric study was inconclusive due to insufficient cells. A diagnosis of EBV-positive GZL was rendered. She has received brentuximab and her symptoms are improving with regressing lymph node size. Results (if a Case Study enter NA) NA Conclusion The presence of EBV positivity in GZL further complicates the diagnostic process, as it adds another layer of complexity in determining the appropriate classification and treatment. Our case highlights the importance of comprehensive morphologic phenotypic and cytogenetic investigation to diagnose GZL.

Solving the mystery of Reed Sternberg like cells in a composite Peripheral T Cell Lymphoma with Epstein Barr Virus and Epstein Barr Virus driven Lymphoproliferative Disorder

Abstract Introduction/Objective Nodal PTCL with EBV positivity can occasionally contain Reed Sternberg-like cells, and EBV- LPD can mimic Hodgkin lymphoma. Coexistence of these two unusual lymphomas in the same lymph node is very rare. We present a case of a 56-year-old male with Composite EBV+ PTCL NOS and EBV LPD, with positive B-cell gene rearrangement and negative T-cell gene rearrangement presenting a significant diagnostic challenge. Methods/Case Report A 56-year-old male with a history of abdominal tuberculosis presented with lethargy, fatigue, and poor appetite. Physical examination revealed generalized lymphadenopathy. CT scan confirmed lymphadenopathy in bilateral axilla, supraclavicular lymph nodes along with lytic lesions on illiac crest. Ill defined splenic lesions raised concerns for metastasis. Cervical lymph node and bone marrow biopsies were performed. Flow cytometry on the lymph node was not done due to tuberculosis history. Flow cytometry on the bone marrow showed an inverted CD4:CD8 ratio. H&E sections of the lymph node revealed a polymorphic lymphoid infiltrate with prominent Reed Sternberg-like cells. Immunohistochemical staining showed CD30-positive and CD45-negative large cells. T-cell and B-cell gene rearrangements were performed. Initially, B-cell gene rearrangements were positive, while T-gamma was negative. Further testing by IHC and morphological evaluation revealed two distinct cell populations, one with CD3, CD5, and CD7 positivity with partial weak positivity for PD1, CD43, and CD8 and the other consisting of B-cells expressing CD30, EBV, MUM1, and partial expression of BCL6 rare CD79a, and partial weak Pax5. Outside molecular testing showed positive T-cell gene rearrangements. The diagnosis of Composite EBV+ Peripheral T Cell Lymphoma, not otherwise specified, with cytotoxic profile along with EBV driven LPD was made. Bone marrow studies confirmed involvement by the same lymphoma. Results (if a Case Study enter NA) NA Conclusion Identifying EBV-positive Reed Sternberg-like cells in both EBV LPD and PTCL-NOS in a composite lymphoma can be challenging. In the absence of flow cytometry, a composite lymphoma can potentially be misdiagnosed, leading to under-treatment. Repeat testing can be helpful in case of any doubt. Although EBV-positive PTCL with cytotoxic profile and EBV-positive LPD has been reported, the combination of these two lymphomas together is exceedingly rare.

Case Report: Gastrointestinal neuroendocrine carcinoma with SMARCA4 deficiency: a clinicopathological report of two rare cases

BackgroundGastrointestinal neuroendocrine carcinoma (GI NEC) is a rare but highly malignant neoplasm with an aggressive clinical course. SMARCA4 is one of the subunits of the SWI/SNF chromatin remodeling complex. SMARCA4 deficiency can occur rarely in subsets of NECs. Reports of the clinicopathological features of GI NECs with SMARCA4 deficiency are limited.MethodsIn this study, we retrospectively reported two rare cases of GI NEC with SMARCA4 deficiency and described the clinicopathological, radiographic and histopathological features.ResultsCase 1 was a 43-year-old male with a stage cT3NxM1, IV tumor. Case 2 was a 64-year-old female with a stage cT4aN1M0, IIIA tumor. Both tumors presented as ulcerated masses with infiltration. Pathological examination indicated a solid architecture with poorly differentiated morphology, and complete loss of SMARCA4 (BRG1) was found. Immunohistochemical staining showed positivity for Syn, CgA and CD56. The Ki-67 index was 90% and 70%, respectively. None of the cases had mismatch repair (MMR) deficiency. Case 1 received treatment with chemotherapy and anti-PD-1 immunotherapy. He did not respond to treatment, and died 9 months later. Case 2 received neoadjuvant chemotherapy before surgical treatment, and the tumor showed TRG3 in response to neoadjuvant chemotherapy, chemotherapy and anti-PD-1 immunotherapy were continued after surgical resection. There was no evidence of disease for 10 months.ConclusionsGI NEC with SMARCA4 deficiency is a rare entity of gastric NEC. SMARCA4 may be a promising targetable and prognostic biomarker. BRG1 immunohistochemical staining could be performed for GI NECs. Further studies with a larger cohort will be needed.

Development and Characterization of a Novel Murine Peripheral T-Cell Lymphoma Cell Line Which Closely Mimics Human Disease

Peripheral T-cell lymphoma (PTCL) represents a heterogenous group of aggressive non-Hodgkin lymphomas with poor prognostic outcomes and limited treatment options. Despite the advances in genomic sequencing and molecular characterization, the complex and elusive nature of PTCL's underlying biology has proven difficult to fully understand and manage effectively. The development and refinement of therapeutic strategies for PTCL are impeded by a paucity of reliable preclinical models that accurately mimic the disease's pathophysiology. There is a dire need for more physiologically relevant models for PTCL. Improved models allow for a better understanding of the disease's molecular and cellular mechanisms, facilitate the development of innovative therapeutic strategies, and ultimately improve patient outcomes. Here we described a new T-cell lymphoma cell line (LM-23) derived from a 12-week-old female Balb/cJ mouse which developed diffuse adenopathy and splenomegaly. Tumors from this mouse were cultured in cRPMI + 10% fetal bovine serum for 4 weeks without supplementation of additional cytokines and passaged 3-4 times per week where we found the cells to be non-adherent. Immunophenotyping of LM-23 demonstrated positivity for CD90, CD3, TCR-beta, CD4(partial/subset), CD8, PD1 (positive), ICOS (positive) and negative for B-cell and myeloid lineage markers (Fig. 1B). This immunophenotype most closely resembles PTCL-NOS in humans at an immunophenotypic characterization level. Whole exome sequencing is in progress and will be presented. Intravenous administration of this cell line to syngeneic Balb/cJ mice resulted in rapid establishment of diffuse adenopathy, splenomegaly, and liver metastases. Bulky adenopathy was observable within 14 days of administration. Histologically, these tumors consisted of sheets of medium to large sized lymphocytes with clumped chromatin and prominent nucleoli, similar to human T-cell lymphomas (Fig. 1A). Subcutaneous administration demonstrated rapid tumor growth with mice reaching terminal endpoints (>2,000mm 3) within 21 days following administration. As CHOP-based (cyclophosphamide, doxorubicin, vincristine, and prednisone) therapies are the primary backbone for treatment of PTCL, we tested whether CHOP therapy alone had anti-tumor activity to LM-23. Tumor bearing mice (~150mm 3) were treated with CHOP and monitored for tumor growth. All mice treated were non-responsive to CHOP therapy with no difference in tumor growth compared to untreated mice. Additionally, LM-23 bearing mice treated with anti-PD1 showed signs of hyperprogression, which has been observed in human patients in clinical trials (Gao Y et al. JCI Insight 2023, Bennani NN et al. Blood Supplement 2019). Additional therapeutic target testing is underway and will be presented. In conclusion, the newly established LM-23 T-cell lymphoma cell line provides a novel, physiologically relevant preclinical model for the study of PTCL. Its phenotypic characteristics, rapid growth, and metastatic behavior in syngeneic mice, along with its resistance to CHOP therapy and hyperprogression upon anti-PD1 treatment, mimicking the clinical scenarios observed in some human PTCL patients. These features highlight LM-23's potential as a valuable tool for understanding the biological mechanisms underlying PTCL and for the development and testing of innovative therapeutic strategies. We hope that the LM-23 cell line will contribute significantly to these efforts, ultimately improving outcomes for patients afflicted with PTCL.

Primary cutaneous CD30+ lymphoproliferative disorders with DUSP22 translocation.

Primary cutaneous CD30+ lymphoproliferative disorders (LPD) encompass abroad category of clonal Tcell proliferations with varied clinical presentations. Classically, lymphomatoid papulosis (LyP) and primary cutaneous anaplastic large cell lymphoma (ALCL) have been recognized as distinct clinicopathological entities according to their differing clinical features. Recently, asubset of LyP and both cutaneous and systemic ALCL have been shown to carry aDUSP22 translocation [1-3], adefining molecular feature for the novel entity "LyP with DUSP22t" [1]. In cutaneous biopsies, both primary cutaneous DUSP22-translocated ALCL and LyP with DUSP22 rearrangements are characterized by abiphasic pattern with significant small cell epidermotropism. Adistinct protein expression profile with preserved T Cell Receptor (TCR) expression, positivity for CD30, LEF1, HLA, and CD58, and negativity for cytotoxic marker expression as well as phospho-STAT3 protein is consistently found in these cases.

Extranodal NK/T-Cell Lymphoma Predominantly Composed of Anaplastic Cells: A Frequently Misdiagnosed and Highly Aggressive Variant.

Extranodal NK/T-cell lymphoma (ENKTL) is a non-Hodgkin lymphoma associated with the Epstein-Barr virus that primarily affects individuals in East Asia and indigenous populations in Central and South America. Morphologically, ENKTL typically consists of medium-sized cells or a combination of small and large cells. This report presents 10 cases characterized by predominantly anaplastic cells with diffuse expression of CD30, resembling anaplastic lymphoma kinase-negative anaplastic large cell lymphoma (ALK-negative ALCL) and demonstrating highly aggressive behavior. The cohort included 9 males and 1 female, ranging in age from 29 to 65 years (median age: 47y). Eight patients presented with nasal disease, while 2 had non-nasal disease. Five patients had stage I/II disease, and the remaining 5 had stage III/IV disease. Morphologically, necrosis was observed in 9 cases, angiocentric-angiodestructive growth in 3 cases, and pseudoepitheliomatous hyperplasia in 2 cases. Anaplastic cells predominated in all cases, with some displaying eccentric, horseshoe-shaped, or kidney-shaped nuclei (referred to as "Hallmark" cells). The morphology profile was monomorphic in 3 cases and polymorphic in 7 cases. Immunohistochemically, all cases tested positive for cytotoxic granule markers (TIA1 and granzymeB) and Epstein-Barr virus-encoded RNA. Cytoplasmic expression of CD3ε and CD56 was observed in 9 of 10 cases. Interestingly, most cases (7 of 8) exhibited variable expression of MuM1, ranging from 10% to 90%. All cases showed diffuse positivity for CD30 but were negative for ALK, resulting in 3 cases being initially misdiagnosed as ALK-negative ALCL. Compared with nonanaplastic cases, anaplastic cells predominant ENKTL had a significantly higher frequency of "B" symptoms, bone marrow involvement, hemophagocytic lymphohistiocytosis, and higher Ki67 proliferative index. These findings provide valuable information for pathologists, expanding their understanding of the cytologic spectrum of ENKTL. This rare variant of ENKTL, characterized by the predominance of anaplastic cells and diffuse CD30 expression, exhibits high aggressiveness and should be differentiated from ALK-negative ALCL. Awareness of this uncommon variant is crucial in preventing misdiagnosis and ensuring the timely initiation of therapy.

UBTF Tandem Duplications in Pediatric MDS and AML: Implications for Clinical Screening and Diagnosis

Recent genomic studies in adult and pediatric acute myeloid leukemia (AML) demonstrated recurrent in-frame tandem duplications (TD) in exon 13 of upstream binding transcription factor ( UBTF) (PMID: 35176137, PMID:37085611). UBTF-TDs are subtype-defining genomic alterations associated with poor outcomes that account for ~4.3% of AMLs in childhood and up to 3% in adult AMLs under the age of 60. UBTF-TD AMLs are characterized by HOXA/HOXB dysregulation, trisomy 8 or normal cytogenetics and frequent FLT3-ITD and/or WT1 mutations. A more comprehensive investigation into the clinicopathological features of UBTF-TD AMLs is needed to better understand disease features for appropriate diagnosis and to develop more effective therapies. Here, we present 94 unique pediatric cases harboring a tandem duplication in exon 13 of UBTF with a median size of 60bp (range 21-1173bp). Of these 94 cases, 6 (6.4%) were diagnosed with childhood MDS with increased blasts (WHO), suggesting that like in adults, UBTF-TDs are not only confined to AML. UBTF-TD AMLs are associated with an overall lower median white blood cell (WBC) when compared to other common HOXA/B dysregulated leukemias ( UBTF-TD median = 10.2x10 9/L, NPM1-mutation median = 21.8x10 9/L, NUP98-rearranged ( NUP98r) median = 97x10 9/L). Available immunophenotyping on 32 U BTF-TD tumors demonstrated positivity for HLA-DR (31/31; 100%), CD117 (28/29; 95%), and CD34 (26/30; 86%) with variable positivity for CD7 (17/30; 56%) and CD64 (13/25; 52%). A limited number of cases tested for CD123 (n=11) and CD11c (n=15) were all positive for the respective marker. Furthermore, morphologic assessment of these cases revealed pleomorphic blasts with occasional Auer rods and increased immature myeloid cells with salmon-colored granules, commonly with background multilineage dysplasia and increased erythroid precursors. At the transcriptional level, UBTF-TD leukemias are largely similar to NPM1-mutated and NUP98::NSD1 AMLs with the exception of UBTF-TD cases having marked increase in expression of histone genes (e.g., HIST1H4F and HIST1H2B1) and a subset of posterior HOXB cluster genes (e.g., HOXB9). Further inspection using UMAP (Uniform Manifold Approximation and Projection) of expression profiles across different pediatric AML cohorts revealed two unclassified cases of AML that clustered with the UBTF-TD subtype ( Figure 1). One case had a WT1p.S364* and the other a somatic GATA2 p.R338fs and FLT3-ITD, but did not contain an exon 13 duplication or other defining alterations. Upon closer inspection of the UBTF gene in these cases, we uncovered that each case had an in-frame tandem duplication in exon 9 of UBTF encoding a region between HMG box 2 and 3 with features similar to those in exon 13 ( Figure 2). We therefore postulated that exon 9 TDs ( UBTF-e9) could represent a functionally equivalent subgroup of UBTF-TDalterations. To test this hypothesis, cord-blood CD34+ (cbCD34+) cells were transduced to test the transforming potential of UBTF-e9 duplications. Like with UBTF-e13 duplications, cbCD34+ cells expressing UBTF-e9 duplications displayed increased proliferation compared to UBTF -WT and lentiviral empty vector control in liquid culture; and increased colony counts and replating capacity, increased CD117 expression, and a more blast-like morphology in CFU assays. Collectively, these data suggest that like TDs in exon 13, exon 9 TDs are also sufficient to promote leukemogenic phenotypes. In conclusion, we find that UBTF-TDs occur in both MDS and AML and are associated with lower WBC count, myelodysplasia, and stem cell-related surface marker expression. We have also expanded the spectrum of UBTFalterations in myeloid neoplasms through the identification of rare UBTF duplications in exon 9 that induce a similar transcriptional signature to exon 13 UBTF-TDs. The recent identification of UBTF-TDs in adult and pediatric high-risk myeloid neoplasms has highlighted the importance of understanding and appropriately diagnosing tumors with this genomic alteration, including a new class of alterations that will not be detected by PCR-based screening strategies that specifically target exon 13 of UBTF.

Intracranial dissemination in a primary small cell carcinoma of the brain: a case report and literature review.

Primary intracranial small cell carcinoma (SCC) is extremely rare with only 8 previously reported cases. We describe a case of primary intracranial SCC with intracranial metastasis. A 46-year-old man presented with decreased vision and a red and swollen left eye. Brain magnetic resonance imaging (MRI) revealed a heterogeneously enhanced tumor on the left frontal lobe. Preoperative systemic computed tomography (CT), MRI, and positron emission tomography (PET)-CT revealed no extracranial tumors. The tumor on the left frontal lobe was excised. Immunohistochemical staining on the excision showed positivity for CD56, synaptophysin (Syn), cytokeratin (CK), and Ki-67 (30%), and negativity for thyroid transcriptional factor-1 (TTF-1), glial fibrillary acidic protein (GFAP), B-cell lymphoma 6 (Bcl-6), multiple myeloma oncogene 1 (MUM-1), C-Myc, Vimentin, P40, P53, CK7, CD3, CD5, CD20, CD79a, CD10, and CD23. The pathological examination strongly suggested that the tumor was a primary intracranial SCC. One year after the surgery, the patient was readmitted with slurred speech and slow movements. Three well-defined tumors were found in the left upper frontal lobe by brain MRI. Tumor resection was then performed. Further immunohistochemical examination of the excised tissue displayed the same pattern as previously, indicating the recurrence of intracranial SCC in the left frontal lobe. The patient received adjuvant chemotherapy and radiotherapy after the tumor resection. At the 2-year follow-up, he remained asymptomatic.

EXTRANODAL NASAL TYPE T/NK CELL LYMPHOMA: CASE REPORT

Female patient, 33 years old, presenting asymptomatic swelling in the right maxilla with elevation of the nose wing, evolving from 30 days, without lymph node enlargement. Computed tomography showed an area of thickening and densification of the skin and subcutaneous tissue at the right nasolabial fold, with contrast enhancement, without a liquefied image and with poorly defined contours with approximately 3.3 cm. A histopathological examination showed fibroconnective tissue with a dense lymphomononuclear inflammatory infiltrate, which was inconclusive. A immunohistochemical study showed presence of lymphocytic infiltrate of small to medium cells with slightly irregular nuclei, with positivity for CD2, CD56, GATA-3, TIA-1 and CD3, and negativity for CD5 and CD7, and a high proliferative index for Ki67 (70-80%). Research for the Epstein-Barr virus revealed diffuse positivity in the tumor cells. The set of findings was suggestive of extranodal T/NK cell lymphoma, nasal type. The patient was referred to hematooncology team. Female patient, 33 years old, presenting asymptomatic swelling in the right maxilla with elevation of the nose wing, evolving from 30 days, without lymph node enlargement. Computed tomography showed an area of thickening and densification of the skin and subcutaneous tissue at the right nasolabial fold, with contrast enhancement, without a liquefied image and with poorly defined contours with approximately 3.3 cm. A histopathological examination showed fibroconnective tissue with a dense lymphomononuclear inflammatory infiltrate, which was inconclusive. A immunohistochemical study showed presence of lymphocytic infiltrate of small to medium cells with slightly irregular nuclei, with positivity for CD2, CD56, GATA-3, TIA-1 and CD3, and negativity for CD5 and CD7, and a high proliferative index for Ki67 (70-80%). Research for the Epstein-Barr virus revealed diffuse positivity in the tumor cells. The set of findings was suggestive of extranodal T/NK cell lymphoma, nasal type. The patient was referred to hematooncology team.

GRANULAR CELL TUMOR IN AN UNUSUAL LOCATION AFFECTING A PEDIATRIC PATIENT: CASE REPORT

Granular cell tumor (GCT) is a rare benign soft-tissue neoplasm of Schwann-cell origin. It most often affects the tongue, followed by floor of the mouth and buccal mucosa, mainly in adult women. A 13-year-old male patient was referred for evaluation of a lesion on the upper lip. Intraoral examination showed a painless sessile nodule, normal color, measuring 1.0 × 0.5 cm, with several months of evolution. Diagnostic hypotheses included neurofibroma, pleomorphic adenoma, and canalicular adenoma. An excisional biopsy was performed, and histopathologic analysis revealed a well-defined proliferation of eosinophilic granular cells, with no typical pseudo-epitheliomatous hyperplasia, and perineural involvement. Immunohistochemistry showed positivity for vimentin, S100, CD56, and CD68. The diagnosis was GCT. After one year of follow-up, the patient showed no signs of recurrence or alterations. GCT is extremely rare, affecting the upper lip in pediatric patients; therefore, it should be considered in the differential diagnosis of lip nodular lesions. Granular cell tumor (GCT) is a rare benign soft-tissue neoplasm of Schwann-cell origin. It most often affects the tongue, followed by floor of the mouth and buccal mucosa, mainly in adult women. A 13-year-old male patient was referred for evaluation of a lesion on the upper lip. Intraoral examination showed a painless sessile nodule, normal color, measuring 1.0 × 0.5 cm, with several months of evolution. Diagnostic hypotheses included neurofibroma, pleomorphic adenoma, and canalicular adenoma. An excisional biopsy was performed, and histopathologic analysis revealed a well-defined proliferation of eosinophilic granular cells, with no typical pseudo-epitheliomatous hyperplasia, and perineural involvement. Immunohistochemistry showed positivity for vimentin, S100, CD56, and CD68. The diagnosis was GCT. After one year of follow-up, the patient showed no signs of recurrence or alterations. GCT is extremely rare, affecting the upper lip in pediatric patients; therefore, it should be considered in the differential diagnosis of lip nodular lesions.