T-cell Receptor Gamma Gene Research Articles

Preliminary assessment of the diagnostic accuracy of cutaneous T-cell lymphoma through deep sequencing of T-cell receptor gamma gene.

The diagnostic challenges in early mycosis fungoides (MF) and other cutaneous T-cell lymphomas (CTCL) persist despite advancements in molecular methods. The study aims to provide a preliminary assessment of next-generation sequencing in analyzing T-cell receptor gamma (TRG) sequences for distinguishing CTCL from benign inflammatory disorders. Skin samples from CTCL and benign inflammatory skin disorders proven clinicopathologically were assessed for TRG by NGS. Our study analyzed skin samples from a total of 36 subjects, comprising 22 cases of CTCL, including 14 MF and 8 other CTCLs, alongside 14 cases of benign inflammatory skin disorders. According to the LymphoTrack criteria, monoclonality was detected in 75.0 % of the overall 24 CTCL patients. Specifically, in MF cases, 10 out of 14 were identified as monoclonality, with all four non-monoclonal cases being in the patch stage. For the other CTCL, 6 out of 8 cases displayed monoclonality. Among the overall 22 CTCL patients, 11 had multiple biopsies, with 9 displaying the same dominant clone across different sites. Among the 14 benign cases, only the case with erythrodermic psoriasis exhibited monoclonality. Our decision tree analysis suggests that a high frequency of the most abundant clone, its ratio to the third most abundant clone, and TRG V-I segment usage are effective markers aiding in diagnosing CTCL. Combination of the clone frequencies, and TRG V segment usage may enhance diagnosis for MF and other CTCLs, aiding in differentiating them from benign conditions. However, molecular diagnosis for patch-stage MF remains challenging.

PCR GeneScan Analysis of Rearranged Immunoglobulin or T-Cell Receptor Genes for Clonality Diagnostics in Suspect Lymphoproliferations.

Assessment of the presence of clonal lymphoproliferations via polymerase chain reaction (PCR)-based analysis of rearranged immunoglobulin (IG) or T-cell receptor (TR) genes is a valuable method in the diagnosis of suspect lymphoproliferative disorders. Additionally, this methodology can be used for evaluating dissemination of lymphoma cells and for studying the clonal relationship between multiple (different locations) and consecutive (over time) lymphomas. Here we describe an integrated approach to assess clonality via analysis of Ig heavy chain (IGH), Ig kappa (IGK), TCR beta (TRB), and TCR gamma (TRG) gene rearrangements, based on the standardized multiplex PCRs as originally developed by the European BIOMED-2 consortium (currently named EuroClonality). The described protocol covers the pre-analytical phase of DNA isolation (from formalin-fixed paraffin-embedded and fresh tissues, body fluids, peripheral blood, and bone marrow), the analytical phase of PCR GeneScan analysis, and the post-analytical interpretation of the obtained profiles, following established guidelines.

Pan-cancer γδ TCR analysis uncovers clonotype diversity and prognostic potential

Gamma-delta Tcells (γδ Tcells) play a crucial role in both innate and adaptive immunity within tumors, yet their presence and prognostic value in cancer remain underexplored. This study presents a large-scale analysis of γδ Tcell receptor (γδ TCR) reads from 11,000 tumor samples spanning 33 cancer types, utilizing the TRUST4 algorithm. Our findings reveal extensive diversity in γδ TCR clonality and gene expression, underscoring the potential of γδ Tcells as prognostic biomarkers in various cancers. We further demonstrate the utility of TCR gamma (TRG) and delta (TRD) gene expression from standard RNA-sequencing (RNA-seq) data. This comprehensive dataset offers a valuable resource for advancing γδ Tcell research, with implications for enhanced immunotherapy approaches or alternative therapeutic strategies. Additionally, our centralized database supports translational research into the therapeutic significance of γδ Tcells.

Conventional PCR-based versus next-generation sequencing-based approach for T-cell receptor γ gene clonality assessment in mature T-cell lymphomas: A phase 3 diagnostic accuracy study.

Clonality assessment is currently the major molecular analysis utilized to support the diagnosis of suspicious lymphoid malignancies. Clonal rearrangements of the V-J segments of T-cell receptor G chain locus (TCRγ or TRG) have been observed in almost all types of T neoplasms, such as T-cell-related non-Hodgkin lymphomas and leukemias. At present, the gold standard for clonality evaluation is multiplex polymerase chain reaction (PCR), plus subsequent capillary electrophoresis/heteroduplex analyses, and/or Sanger sequencing. This approach overcomes the problem with the conventional Southern blot hybridization and is more efficient, simple, fast, and reproducible. In the recent years, the new next-generation sequencing (NGS) technologies provided alternative techniques for the analysis of antigen receptors genes, which presented several advantages, such as increased efficiency, specificity (SP), sensitivity (ST), resolution, and objectivity of the results, leading to a better classification, stratification, and monitoring of lymphoid malignancies. Nonetheless, these technologies are still far from being the new gold standard since further studies are warranted to prove their utility. The present study aimed to assess the diagnostic accuracy of these two methods by comparing a commercial NGS-based assay for the evaluation of TRG locus with the gold standard PCR-based one, to fulfill the requirements of a phase 3 diagnostic accuracy study. We assessed the TRG gene rearrangements in 72 cases using the conventional and highly-validated PCR-based assay proposed by EuroClonality consortium, an alternative commercial PCR-based assay, namely, IdentiClone® TCR Gamma Gene Rearrangement Assay 2.0, and a commercial NGS-based assay, that is, Invivoscribe LymphoTrack® Dx MiSeq® (both by Invivoscribe Technologies Inc., San Diego, CA, USA), to determine the diagnostic accuracy of the latter, and compare them with reference diagnoses made based on observation of clinical manifestations, cytohistological, and immunohistochemical analyses. Statistical values were calculated using the Oxford CATmaker software package. Using standardized criteria of interpretation, the obtained results showed a diagnostic accuracy of 90.3% (correspondence in 65 out of 72 cases) of the test under investigation, with a ST of 86%, a SP of 95%, a positive predicting value of 94%, and a negative predicting value of 88%, demonstrating that it had high efficiency and reliability in detecting clonal TRG gene rearrangements in T-cell non-Hodgkin lymphomas. This diagnostic accuracy study yielded comparable results using a validated PCR-based approach and a new NGS-based one. Subsequent studies and cost-effectiveness evaluation are needed to put the NGS-based clonality assessment into routine diagnostic practice.

Comparative analysis of primer sets for the assessment of clonality in feline lymphomas.

Lymphomas are among the most important and common malignant tumors in cats. Differentiating lymphomas from reactive lymphoid proliferations can be challenging, so additional tools such as clonality assessment by PCR are important in diagnosis finding. Several PCR assays have been developed to assess clonality in feline lymphomas. For T-cell lymphomas TRG (T-cell receptor gamma) genes are the preferred target whereas for B-cell lymphomas most primer sets target immunoglobulin heavy chain (IGH) genes. Here we compare commonly used diagnostic primer sets for the assessment of clonality in feline lymphomas under controlled conditions (i.e., identical sample set, PCR setup, amplicon detection system). Formalin-fixed and paraffin-embedded samples from 31 feline T-cell lymphomas, 29 B-cell lymphomas, and 11 non-neoplastic controls were analyzed by PCR combined with capillary electrophoresis. We show that the combination of the primer sets published by Weiss et al. and Mochizuki et al. provided the best results for T-cell clonality, i.e., correctly assigns most populations as clonal or polyclonal. For B-cell clonality, the combination of the primer sets by Mochizuki et al. and Rout et al. gave the best results when omitting the Kde gene rearrangement due to its low specificity. This study rigorously evaluated various primer sets under uniform experimental conditions to improve accuracy of lymphoma diagnostic and provides a recommendation for achieving the highest diagnostic precision in lymphoma clonality analysis.

Molecular and clinicopathological features of granzyme B-negative extranodal NK/T-cell lymphoma

Extranodal NK/T-cell lymphoma (ENKTL) generally expresses cytotoxic molecules, including granzyme B (GZMB), T-cell-restricted intracellular antigen-1 (TIA-1), and perforin; however, the expression of these molecules varies across cases. We performed gene expression profiling and identified unique biological and clinicopathological features of GZMB-negative ENKTL. We reviewed the clinicopathological characteristics of 71 ENKTL samples. Gene expression profiling on nine ENKTLs using multiplexed, direct, and digital mRNA quantification divided ENKTLs into Groups A (n = 7) and B (n = 2) through hierarchical clustering and t-distributed stochastic neighbor embedding. Group B was characterized by downregulation of genes associated with IL6-JAK-STAT3 signaling and inflammatory responses. GZMB mRNA expression was significantly downregulated in Group B. GZMB protein expression was evaluated with immunohistochemistry in all 71 ENKTLs, and expression data of Tyr705-phosphorylated STAT3 (pSTAT3) and MYC from our previous study was utilized. T-cell receptor gamma (TRG) gene rearrangement in the selected samples was also assessed using PCR. GZMB expression was higher in pSTAT3-positive (p = 0.028) and MYC-positive (p = 0.014) ENKTLs. Eighteen percent (13/71) of all ENKTLs were negative for GZMB (defined by positivity <10 %); patients with GZMB-negative ENKTLs were often in a higher clinical stage (p = 0.016). We observed no other correlations with clinical parameters or TRG rearrangement and no significant association between GZMB expression and survival. In conclusion, GZMB expression is highly heterogeneous in ENKTLs and is associated with the activation of the JAK-STAT3 pathway and higher MYC expression. GZMB-negative ENKTLs correlate with an advanced clinical stage, suggesting the potential utility of GZMB immunohistochemistry as a biomarker of ENKTL.

Anaplastic Large Cell Transformation of Mycosis Fungoides: Case Report and Review of the Literature.

We report a 48-year-old man with CD30+ large cell transformation of mycosis fungoides (tMF) with distinctive anaplastic morphology. The patient initially presented with folliculotropic and syringotropic mycosis fungoides (MF) manifested as occipital scalp plaque and trunk and extremities patches. Six years later, he progressed to the tumor stage from his scalp lesion and developed cervical lymphadenopathy. Lymph node and scalp biopsies showed diffuse infiltration of CD30+ anaplastic cells with multinucleated, hallmark-like, Hodgkin-Reed-Sternberg-like, histiocytoid forms, indistinguishable from anaplastic large cell lymphoma (ALCL). T-cell receptor gamma gene (TCRg) rearrangement studies revealed identical clones in the initial MF scalp lesion and nodal anaplastic lesion, confirming the transformation. Ancillary studies showed absence of IRF4/DUSP22 and ALK rearrangements and positive RB1, SMARCA4, SOCS1, and TP53 mutations. The patient achieved partial response with systemic chemotherapy. Our case is an example of tMF presenting as the morphology and phenotype of ALCL. Because clinical behavior and therapeutic options of tMF and primary cutaneous ALCL may be different, it is clinically relevant to differentiate these 2 entities. The proof of clonal relationship may be useful in diagnostically challenging cases with features overlapping between tMF and primary cutaneous ALCL.

An integrated cytomorphology and sequencing analysis for hepatosplenic alpha/beta T-cell lymphoma.

A 47-year-old male with a past medical history of diabetes mellitus under the control of oral hypoglycemic medications developed nausea and intermittent fever for weeks. Physical examination showed splenomegaly (4 cm below the costal margin) without significant lymphadenopathy. Laboratory data showed pancytopenia (Hemoglobin: 11 g/dl, White blood cells: 1.53 k/μl, Platelet: 47 k/μl), elevations of liver function tests (totalbilirubin: 1.38 mg/dl, direct bilirubin: 0.65 mg/dl, alanine transaminase (ALT): 56 U/L, aspartate transaminase (AST): 103 U/L, gamma-glutamyl transferase (GGT): 515 U/L, alkaline phosphatase (ALP): 260 U/L) and serum lactate dehydrogense (LDH) level (311 U/L, 1.1X). Flow cytometry of peripheral blood revealed that the abnormal lymphoid cells accounted for 4.3% of total nucleated cells, larger-than-normal lymphocytes, with positive expression of CD2, CD3, CD7, CD8, CD56 and negative for CD5 and CD45. Bone marrow (BM) aspirate revealed abundant lymphoma cells, med- to large-sized, with pleomorphic nuclei, prominent nucleoli, and coarse cytoplasmic granules (Figure 1). BM biopsy showed hypercellularity and the CD3+ lymphoma cells were negative for CD45, CD34, CD117, TdT, CD79a, and Epstein-Barr virus-encoded RNA (EBER) staining, with the pattern of sinusoidal infiltration (Figure S1). BM flow cytometry gating on the lymphoma cells confirmed the positive expression of CD2, CD3, CD7, CD8, CD56, T-cell receptor (TCR) alpha-beta chains, perforin, granzyme B, and negative for CD34, CD4, CD5, and TCR gamma-delta chains (Figure 2), consistent with natural killer (NK)/T lymphoma involvement. Cytogenetic analysis of the bone marrow was normo-karyotypic. Fluorodeoxyglucose-positron emission tomography (FDG-PET) scans revealed hypermetabolism in hepatosplenomegaly (maximum standardized uptake value (SUVmax) = 7.72 in spleen), bilateral cervical nodes, right supraclavicular nodes, right paratracheal nodes (SUVmax = 4.64), L4 (SUVmax = 5.03) and T9 vertebral bodies (SUVmax = 6.3) (Figure 3). Next-generation sequencing of BM TCR gamma gene VJ-recombination was indicative of monoclonality of T cells (59.52% of total reads) (Figure 4). This hepatosplenic T-cell lymphoma, alpha-beta type, Ann Arbor stage IV was thus diagnosed. He received three cycles of chemotherapy L-CHOEP (L-asparaginase, cyclophosphamide, doxorubicin, vincristine, etoposide, prednisolone) followed by a myeloablative matched sibling peripheral stem cell transplant. He remained free from relapse 14 months post-transplant with a normal hemogram and normal-metabolic FDG-PET scans. We acknowledge the service provided by the Department of Pathology, National Taiwan University Hospital. The authors declare no conflict of interest. We obtained informed consent from the patient. We have IRB approval from Research Ethics Committee A National Taiwan University Hospital with IRB number: 201910033RSB (Case number: 01–0019). Data are available in the article's Supporting Information. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Diagnostic utility of the lymphoid screening tube supplemented with TRBC1 for the assessment of T-cell clonality.

Flow cytometric panels for the investigation of lymphoproliferative disorders, such as the EuroFlow Lymphoid Screening Tube (LST), often fail to demonstrate T-cell clonality, as a suitable clonality marker was unavailable until recently. Aim of this study was to evaluate the added value of supplementing TRBC1, a flow cytometric T-cell clonality marker, to the LST. Flow cytometric analysis was performed on 830 routine samples referred to our lab for suspicion of hematological malignancy. T-cells with monotypic TRBC1-expression were additionally characterized with a 12-color T-cell tube and molecular T-cell receptor gamma gene rearrangement (TRG). LST analysis revealed 97 (11.7%) samples with the presence of a monotypic T-cell population according to TRBC1, including 21 (2.5%) "high-count" (≥500 cells/μL blood or ≥15% of lymphocytes) and 76 (9.2%) "low-count" (<500 cells/μL blood or <15% of lymphocytes) populations. Clinical symptoms indicative for T-CLPD could be correlated to 11/21 "high-count" and 17/76 "low-count" monotypic T-cell populations. Molecular TRG analysis demonstrated a monoclonal result in 76% (16/21) of "high-count" samples and in 64% (42/66; 10 samples not tested) of "low-count" samples, but also in 9/20 samples with polytypic TRBC1 results. Analysis of an LST tube supplemented with TRBC1 led to the detection of a high number of monotypic T-cell populations. The detection of numerous small monotypic T-cell populations raises the question of their clinical significance. A possible flowchart for assessment of these populations, based on the available literature, is proposed. Molecular TRG analysis is complementary and cannot be omitted from T-cell clonality assessment.

Patterns of Lymphocytic Infiltrates Can Differentiate Feline Hepatic Lymphoma from Lymphocytic Portal Hepatitis.

Hepatic lymphoma is poorly characterized in cats and differentiating between inflammation and lymphomas is often difficult. The diagnosis of hepatic lymphoma in humans relies on recognition of specific patterns of lymphocytic infiltrates and clonality testing of antigen receptors. Herein, we defined similar patterns of lymphocytic infiltrates in hepatic biopsies of cats and correlated them with clonality to determine which patterns are predictive of lymphoma. A retrospective study was performed on surgical biopsies from 44 cats. The immunophenotype was characterized using CD3 and CD20 on all 44 samples. All 44 samples were tested using PCR for T-cell receptor gamma-gene rearrangements. PCR for immunoglobulin heavy chain gene rearrangements was performed on 24 of these cats. Four patterns of lymphocytic infiltrates were characterized: (1) tightly periportal, (2) periportal and centrilobular, (3) nodular, and (4) periportal with sinusoidal extension. Other histomorphologic features (fibrosis, biliary hyperplasia, bile ductopenia, bile duct targeting, hepatic hematopoiesis, lipogranulomas, lymphonodular aggregates, other inflammatory cells) were also evaluated. The sensitivity and specificity of the lymphocytic patterns to diagnose lymphomas were determined using Bayesian Hui-Walter analysis (BLCM) against clonality results. Lymphocytic patterns 2, 3, and 4 accurately diagnosed hepatic lymphomas with a sensitivity and specificity of 82% (CI 95%: 0.65, 0.96) and 77% (CI 95%: 0.54, 1.00), respectively. None of the other microscopic features evaluated were predictive of a lymphoma or inflammation. Our study identified specific patterns of lymphocytic infiltration that differentiate feline hepatic lymphoma from inflammation while other histologic features were not associated with an accurate diagnosis.

T-Cell Monoclonality in the Blood and the Skin Correlates With Poor Response to Treatment in Mycosis Fungoides.

The prognostic value of skin and blood T-cell receptor clonality in mycosis fungoides is a matter of debate. Our aim was to ascertain the relation between the presence of a monoclonal T-cell population in the blood and in the skin with response to treatment in patients with mycosis fungoides. Clinical features and follow-up data were retrospectively collected and analyzed in 94 patients with mycosis fungoides seen at a cutaneous lymphoma clinic in a single tertiary center. All patients had results of polymerase chain reaction analysis of T-cell receptor gamma gene rearrangement in lesional skin and in peripheral blood at time of diagnosis. Association of response to treatment with clonality in the tissue and in the blood was assessed. T-cell monoclonality was detected in the skin in 30 of 94 patients, in the blood in 12 of 94 cases and the same clone was found in both tissues in 6 of 94 patients. The presence of a polyclonal T-cell population in the circulation was associated with complete response (P=.006). Lack of response to treatment (stable disease or progression of disease) was associated with T-cell clonality in skin (P=.009), in blood (P=.002) and in both tissues (P < .001). A multivariate analysis showed that T-cell monoclonality in the skin is independently associated with lack of response of mycosis fungoides to therapy. Blood and skin should be studied for T-cell clonality as part of the routine initial workup, even in patients with early-stage disease.

Focal Myositis with CD8+T-Cell predominance: an Inflammatory Myositis Mimicking a Soft Tissue Neoplasm

Abstract Introduction/Objective FM is a rare self-limiting T-cell rich lesion arising within muscles of young adults as a solitary lesion and can be confused with a variety of neoplastic/inflammatory conditions or lymphoma. Here we describe a rare T-cell rich variant of FM with CD8 predominance. Methods/Case Report A 51-year-old female presented with two-month history of left trapezius swelling. MRI showed an enhancing tumor within the muscle, suspicious of sarcoma, less likely myeloma. Results (if a Case Study enter NA) Biopsy showed diffuse infiltration of small lymphocytes in a fibrotic background and atrophic skeletal muscle. These lymphocytes stained positive for CD2, CD3, CD7, CD8, CD5 (partial), TIA1 (partial), CD43, CD57 and negative for CD4, CD30, CD56, CD57, granzyme B, perforin, BCL-6, BCL-2, Pax5, TCL1, and CD56. Ki-67 was (&amp;lt;10%) with few background CD20+ B cells. By flow cytometry, the CD8+ T-cells co-express CD2, CD3, CD7, with dim CD5 expression. TCR gene rearrangement study by PCR showed no clonal TCR Gamma gene rearrangement. Conclusion FM is extremely rare with only 22 cases well-described in the literature, all predominantly composed of CD4+ T-cells, clinically concerning for low-grade sarcomas, as inflammatory myofibroblastic tumor, inflammatory leiomyosarcoma, or liposarcoma. Careful analysis is essential for correct diagnosis. Mimics include other causes of myositis, such as polymyositis and inclusion body myositis. Depending on the extent of lymphocytic infiltrate, gene rearrangement studies might be necessary to rule out clonality. Recognition of this rare entity with excellent prognosis is crucial to provide appropriate management and avoid unnecessary, aggressive procedures.

A Unusual Case of Classic Hodgkin Lymphoma (cHL) with Aberrant T-Antigens Expression

Abstract Introduction/Objective T-cell-associated antigens (TCA) are rarely expressed by Hodgkin/Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL) and is associated with uncertain clinical significance. Methods/Case Report We present a very recent case of a 68 year-old female with no significant past medical history presented with a large right groin mass for 1 month. She denied any fever, night sweats, fatigue or weight loss. CT abdomen/pelvis showed inguinal/pelvic lymphadenopathy. Resection showed effaced nodal architecture with a vague nodular appearance and with large, atypical nucleolated cells in a background of small, mature lymphocytes and histiocytes. Eosinophils are conspicuously absent in the background. The large cells were polylobated lymphocyte and histiocyte rich (L &amp; H) like, classic HRS cells as well as multinucleated in appearance. The morphologic features overlapped between Classic Hodgkin Lymphoma, and Nodular Lymphocyte Predominant Hodgkin Lymphoma. Given the immunohistochemical (IHC) features of the neoplastic cells [CD45 negative, PAX5+ (weak), CD30+ (strong), CD15+ (majority) and MUM1 +] the diagnosis was most compatible with CHL. Interestingly, a subset of the Hodgkin cells (10-20%) aberrantly expressed a number of T-cell markers (CD2, CD3, CD4, and CD8). However, the background smaller T-cells did not show cytologic atypia or aberrancies of T-cell antigen markers. The large cells were negative for CD43 and ALK1. TCR gamma gene rearrangement was also negative for clonal T-lymphocytes, thus excluding the possibility of peripheral T-cell lymphoma with Hodgkin-like cells. Based on the morphology and IHC profile, this case proves to be CHL with multiple TCA expression including CD2, CD3, CD4 and CD8. She was planned for chemotherapy. Four months after the initial diagnosis and after completion of 2 cycles of chemotherapy, her PET CT scan showed improvement with right inguinal adenopathy being smaller in size and decreased avidity, indicating a response to treatment. She is due for 2 more cycles. Till todate she is doing well with no further symptoms. Results (if a Case Study enter NA) NA. Conclusion So far reported cases of classic Hodgkin lymphoma (CHL) with aberrant T-cell antigen (TCA) expression were associated with decreased event-free survival and overall survival when compared with TCA-negative CHLs. Our finding contributes to the literature and improves our knowledge of the disease.

Overlapping Features of Primary Cutaneous Marginal Zone Lymphoproliferative Disorder and Primary Cutaneous CD4 + Small/Medium T-Cell Lymphoproliferative Disorder : A Diagnostic Challenge Examined by Genomic Analysis.

Primary cutaneous marginal zone lymphoproliferative disorder (PCMZL) and primary cutaneous CD4 + small/medium T-cell lymphoproliferative disorder (CD4 + TLPD) are indolent lymphoproliferative disorders. However, cases with overlapping features can be challenging. We identified 56 CD4 + TLPD and 38 PCMZL cases from our pathology archives. Clinical, morphologic, and immunophenotypic features were reviewed. Polymerase chain reaction for immunoglobulin (IG) and T-cell receptor gamma (TRG) gene rearrangements were analyzed. Next-generation sequencing studies were performed on 26 cases with adequate material, 19 with CD4 + TLPD, and 7 with PCMZL. CD4 + TLPD presented mostly (91%) as solitary lesions, located in the head and neck area (64%), while PCMZL occurred mostly in the upper extremity (47%) and trunk (34%). Lesions were sometimes multiple (40%) and recurrences (67%) were more common. Cases of PCMZL had an increase in reactive CD3 + T cells, with frequent programmed cell death protein 1 expression, whereas cases of CD4 + TLPD often contained abundant reactive B cells. Twenty-five cases were identified as having overlapping features: 6 cases of PCMZL were clonal for both IG and TRG; 11 cases of CD4 + TLPD were clonal for IG and TRG and 6 cases of CD4 + TLPD had light chain-restricted plasma cells. By next-generation sequencing, 23 variants were detected in 15 genes, with PCMZL more likely to show alterations, most commonly affecting TNFAIP3 and FAS, altered in 5 cases. Both entities have an indolent clinical course with response to conservative therapy and management, and warrant interpretation as a lymphoproliferative disorder rather than overt lymphoma.

S3445 Microscopic Enteritis: A Rare Manifestation of T-cell Promyelocytic Leukemia

Introduction: An abnormal infiltration of intraepithelial lymphocytes in the intestinal mucosa is described as microscopic enteritis (ME). ME is a heterogeneous condition that can be found in, but not limited to, celiac disease, autoimmune disorders, food protein intolerance, parasitic infections, and NSAID use. Thus, an obvious cause of ME is difficult to elucidate and requires thorough work up. We report a case of a patient who was found to have ME thought to be secondary to infiltrative T-cell promyelocytic leukemia (T-PLL). Case Description/Methods: A 68-year-old male with a history of type II diabetes and hyperlipidemia presented with intermittent fever, abdominal pain, nausea, and emesis. He was found to have small bowel obstruction with severe enteritis of 3/4 of the small bowel (distal jejunum to the ileocecal valve). He had a small bowel resection with pathology revealing necrotizing lymphocytic enteritis. Bidirectional endoscopy revealed mild colonic, ileal and duodenal edema with biopsies revealing increased intraepithelial lymphocytes. He was empirically treated with intravenous methylprednisolone with resolution of fevers. He was discharged home with a follow up with gastroenterology for ME and with hematology for persistent leukocytosis. He continued to have recurrent fevers with persistent lymphocytic leukocytosis (14,200 WBC/microliter). Infectious (acid fast bacteria, fungi, cytomegalovirus, adenovirus, syphilis) and rheumatologic diagnostics were unrevealing. He underwent bone marrow biopsy and peripheral blood examination with immunostains, flow cytometry, and cytogenetic studies and was found to have clonal T-cell receptor gamma gene rearrangement concerning for T-PLL. He was treated with alemtuzumab; however developed worsening disease and disseminating opportunistic infections (cytomegalovirus and aspergillosis). He passed away shortly after his diagnosis. Discussion: ME is a challenging diagnosis as its etiology can be difficult to elucidate. Prompt, timely evaluation should be prioritized to improve outcomes. T-PLL is a rare leukemia due to abnormal growth of T-lymphocytes and typically presents with leukocytosis, weight loss, and infection; however, gastrointestinal symptoms may be a presenting symptom.

Chronic Lymphocytic Leukemia, T-Cell Large Granular Lymphocytic Leukemia in a Pediatric Patient without Underlying Condition

BackgroundLarge granular lymphocytic (LGL) leukemia is a rare hematological malignancy in children. The two types of LGL leukemia that have been described are T-cell and Natural Killer cell leukemia. It is most commonly diagnosed in older adults, average age of 60-year-old. About 20 cases of LGL leukemia have been reported in children and young adults. All the patients in the reported cases had immune dysregulation conditions, such as chronic graft versus host disease, common variable immunodeficiency disorder, Crohn's disease and autoimmune hemolytic anemia. Here we report a case of T-cell LGL leukemia in a 11-year-old boy without underlying condition who presented with chronic neutropenia associated with gingival hypertrophy, recurrent skin abscesses, aphthous ulcers, clubbing of nails and low bone density.MethodsMulti-institution collaboration and literature review.Case Description11-year-old male with two years history of episodic gum bleeding with gingival hypertrophy, skin abscesses, aphthous ulcers, chronic neutropenia and lymphocytosis presented to our clinic for further evaluation. Initial workup demonstrated moderate to severe neutropenia (absolute neutrophil count between 400/ul to 800/ul) with low segmented neutrophils of 2-4% and high lymphocytes of more than 80%, but normal white blood cell count, hemoglobin for age and platelet count. Peripheral blood smear showed several variant lymphocytes with cytoplasmic blebs and no immature cells present. Expansion of T-cell large granular lymphocytes were detected in peripheral blood by flow cytometry. Due to new symptom of lower back pain, a lumbar Magnetic Resonance Imaging was performed. Results showed low bone density with mild compression deformity of L1 and abnormal heterogeneous marrow signal with heterogeneous contrast enhancement. The abnormal bone marrow signal promoted the investigation of bone marrow aspiration and biopsy. Flow cytometry detected forty-five percent of lymphocytes with immuno-phenotype of CD3+, CD8+, CD57+, CD16+, CD7+ and CD5-. The morphology of minimal cytoplasm and mature chromatin along with immunophenotype were consistent with clonal T-cell large granular lymphocytic proliferation/leukemia. Further cytogenetic tests showed TCR gamma and beta genes rearrangement, STAT3 N647I mutation with normal male karyotype. A peripheral blood congenital neutropenia panel, which included a total of 18 genes, found a heterozygous mutation c 279 G>A in the Gata2 gene; a variant of uncertain significance. Next generation sequencing showed somatic mutations of TRGV10, TRGV8 TRGJ1, TNFAIP3 and STAT3. However, there was no germline mutations detected in sample from skin biopsy. Comprehensive evaluation by immunology, rheumatology and gastroenterology failed to detect any underlying conditions.ConclusionDue to rarity of LGL leukemia in pediatrics, standard of care guidelines are currently unavailable. Extrapolated from limited literature, two management options are considered: watch and wait approach versus early initiation of immunosuppressant chemotherapy. Improved diagnostics can aide management strategies in this patient population. DisclosuresNo relevant conflicts of interest to declare.

Treatment of indolent cutaneous T-cell lymphoma with hypofractionated radiation therapy in three cats.

Feline indolent cutaneous T-cell lymphoma (ICL) is an uncommon neoplastic disease. There is currently no consensus on treatment recommendations for ICL. To report the clinical outcome of three cats with ICL treated with hypofractionated electron-beam radiotherapy (RT). Three privately owned cats with ICL. Medical records and client surveys were reviewed. A diagnosis of probable ICL was based on history, clinical presentation and histopathological findings, and confirmed using CD3 immunohistochemical analysis and PCR for antigen receptor gene rearrangement (PARR). All cats were treated with hypofractionated RT (four fractions of 8Gy). All cats presented with skin lesions characterised by erythema and alopecia that were refractory to previous treatment with systemic glucocorticoids. Before hypofractionated RT treatment, lesions were histologically described as having diffuse infiltration of the dermis with CD3+ T cells. Molecular clonality analysis revealed clonal T-cell receptor gamma gene rearrangement. After RT, two cats showed histological improvement defined by decreased infiltration of lymphocytes, with cellular infiltrate present only in the deeper dermis; one cat had near complete histological resolution of lesions with only minimal residual lymphocytes. One cat was determined to have a complete clinical response while the other showed partial responses. No acute adverse effects of radiation were observed; chronic effects included leukotrichia, partial alopecia and mild fibrosis. All clients reported improvement in quality of life for their cats. Clinical and histological improvement in these cats suggests that hypofractionated RT can be a useful treatment modality for cats with ICL.

TCR γδ Large Granular Lymphocyte Leukemia (LGLL) Displays Features between CD8+ and CD4+ TCR αβ LGLL

BackgroundT-large granular lymphocyte leukemia (T-LGLL) is a rare and heterogeneous lymphoproliferative disorder characterized by the chronic proliferation of clonal Large Granular Lymphocytes (LGLs) with cytotoxic activity. Usually, leukemic cells of this T-cell neoplasia express the αβ T-cell receptor (TCR); only a small subset of cases expresses the γδ TCR denoting the TCRγδ-LGLL. Currently, among the different LGL diseases, TCRγδ-LGLL remains less studied and several clinical and laboratory data already described in TCRαβ-LGLL have not yet been explored in TCRγδ-LGLL. In particular, data are still missing about STAT3 and STAT5b mutations, frequently observed in TCRαβ-LGLL, and about T-LGL clonotypes discovered to be private to TCRαβ-LGLL as compared to healthy controls.AimsThis work was aimed to perform the analysis on: STAT3 and STAT5b mutations, LGL immunophenotype, TCRγ clonotype repertoire and clinical presentations in a group of TCRγδ-LGLL patients. The objective was to reveal common and different features of this rare kind of LGLL with the more frequent TCRαβ-LGLL.MethodsThe cohort of study included 11 patients affected by TCRγδ-LGLL. Sanger sequencing was used for mutational analysis on hot-spot regions of the 2 genes more frequently mutated in LGL disorders, STAT3 and STAT5b . Immunophenotype of LGL clone was defined by flow cytometry analysis. CDR3 repertoire and frequency distribution of TCR gamma gene rearrangements were obtained by Next-Generation Sequencing (NGS).ResultsTCRγδ-LGLL showed a higher occurrence of STAT mutations (82%) as compared to TCRαβ-LGLL (43%). In detail, 9 out of 11 TCRγδ LGLL patients were characterized by STAT3 or STAT5b mutations in a mutually exclusive pattern. Being characterized by both STAT3 and STAT5b mutations, TCRγδ LGLL resembles both CD8+ TCRαβ-LGLL and CD4+ TCRαβ-LGLL, the first being mostly associated to STAT3 mutations and the latter to STAT5b . Similarly, TCRγδ-LGLL showed the same relationship observed between immunophenotype and kind of mutation in TCRαβ-LGLL: TCRγδ-LGLL patients with CD56- LGL immunophenotype were characterized by STAT3 mutations (as in CD8+ TCRαβ-LGLL), while TCRγδ-LGLL patients with CD56+ LGL immunophenotype by STAT5b mutations (as in CD4+ TCRαβ-LGLL). Anyway, in TCRγδ-LGLL no correlation was found between mutations and clinical course as observed in CD8+ TCRαβ-LGLL patients carrying STAT mutations, rather, we observed that patients with γδLGLs positive for Vδ2 showed frequently indolent course, while Vδ1 was associated to a more symptomatic disease (4 out of 5 symptomatic patients were Vδ1+). By NGS we obtained the TCR gamma repertoire of each patient and we revealed that all patients were clonal with the exception of 2 showing a polyclonal pattern. The 2 polyclonal cases were the only 2 patients without STAT mutations. Among the remaining STAT3 mutated patients (n=4), 3 were polyclonal and one biclonal, while STAT5b mutated patients (n=5) were more frequently monoclonal (4/5 monoclonal and 1/5 biclonal). Considering the CDR3 repertoire of the immunodominant clones, as observed in TCRαβ-LGLL, common clonotype sequences were present with low frequency in almost all TCRγδ-LGLL patients. Interestingly, 2 different CDR3 sequences were found shared in different patients at frequency >10% of the total rearrangements. In terms of clonal rearrangements, Vγ3-Jγ1/2, Vγ9-JγP and Vγ8-Jγ1/2 were the combination usages most frequently detected, showing a limited combinatorial diversity of TCR genes similarly to CD4+ and differently from CD8+ TCRαβ-LGLL, this last having larger variability. Analysis about the clonotype repertoire in a 2 years-follow up showed that patients maintain their clonal pattern along the time.ConclusionsOur results highlight common and different characteristics of TCRγδ-LGLL as compared to TCRαβ-LGLL. The data suggest that TCRγδ-LGLL can be considered the intersection of the 2 types of TCRαβ-LGLL, sharing CD8+ or CD4+ T-LGLL mutational and phenotype features. Similarly to TCRαβ-LGLL, also TCRγδ disease showed a decreased diversity of TCR repertoire, with common TCR sequences shared among patients and with limited number of Vγ-Jγ combinations. A distinctive feature of TCRγδ-LGLL is that STAT mutations do not correlate with a symptomatic clinical behavior, rather, Vδ1 expression appears to be indicative for symptomatic disease. DisclosuresGalimberti:Bristol-Myers Squibb: Speakers Bureau; Novartis: Speakers Bureau; Incyte: Speakers Bureau; Pfizer: Speakers Bureau.

T-Cell Monoclonality As Assessed By TCR-Sequencing: A Potential Biomarker of Response in Patients with MDS with Autoimmune Cytopenias Treated with IVIG

Background: We have previously reported 75% of patients (pts) achieved clinical responses to treatment with intravenous immunoglobulin (IVIG) in pts with myelodysplastic syndromes (MDS) that exhibit autoimmune cytopenias in the context of T-cell clonality. T-cell clonality was previously determined via peripheral blood (PB) gel-based testing of T-cell receptor (TCR) beta (TRB) and/or gamma (TRG) gene rearrangements or flow cytometry. IVIG was shown to be variably effective in normalizing hemolytic parameters and cytopenias (Feld et al, Blood 2019). Since next generation sequencing of TRG and TRB (TCR-seq) offers better resolution as to the identity of T-cell clones, we reassessed T-cell clonality in a subset of our cohort and longitudinally evaluated the persistence of clones with IVIG treatment. Methods: Among 27 pts who were previously treated with IVIG +/- steroids, we processed the PB of 9 pts who had serial samples of leftover DNA available for TCR-Seq analysis (7 had samples available prior to treatment). Clinical responses were per MDS IWG 2006 criteria, whereas hemolytic responses were established by either a complete normalization or a mild response if there was &amp;gt;50% improvement in hemolytic parameters from baseline. TCR-Seq was performed on 100ng DNA using the Lymphotrack® TRG and TRB Assays on Illumina® MiSeq platform according to manufacturer's instructions (Invivoscribe, Inc.). Using the LymphoTrackMiseq2.4.3 software T-cell clonality was interpreted as monoclonal (MC), oligoclonal, small clone(s) of uncertain significance (SCUS) or polyclonal (PC), based on percent total merged clonal reads and polyclonal background. Results: Baseline characteristics of our 9 pt cohort included 8 males and 1 female, a median age of 70 years (range 45-82), and a median duration of treatment with IVIG of 23 months. Six pts received steroids in addition to IVIG. Diagnosis included 8 pts with MDS and one with large granular lymphocytic (LGL) leukemia. Of the MDS pts measurable by IPSS criteria, 6 were Int-1 and one was low risk. Expanded lymphocyte populations were detected in 7 pts by PB flow cytometry and all pts exhibited T-cell clonality by gel-based assessment. All were TRB positive (+) and 7 were TRG+ by PCR. In 3 pts, 4 serial samples were available for TCR-seq; 4 pts had 3 samples available and 2 had only 2 serial samples. Samples were collected over a period of 5 months up to 4-5 years. With the better resolution afforded by TCR-Seq, 3 pts exhibited only PC populations of T-cells for TRG and TRB at all time points, and 1 pt exhibited SCUS in 1 of 3 samplings for TRG. Of the four pts, only one had an erythroid response; importantly, this sample was tested after treatment. One pt had a normalization in their bilirubin, otherwise only mild responses in hemolytic parameters were noted in the remaining 3 PC pts. Median duration of treatment was 1.5 months. Five pts had a MC TRB and/or TRG population by TCR-Seq. Two pts had MC TRG, two had MC TRG &amp; TRB, and one had MC TRB populations. Four of the 5 pts had hematologic improvement (HI): 1 had an erythroid and platelet response, 2 had an erythroid response, and 1 had a platelet response. More significant hemolytic responses were also observed in 3/5 pts, with a mild response in the 2 remaining pts. Only 1 TCR-Seq+ pt had no HI, and this pt had a monoclonal population detected by TCR-Seq after finishing IVIG treatment. Median duration of treatment was 45 months. For all these cases, the same clonal sequences were found across all samples up to 4-5 years. Of 4 evaluable patients, 3 had reductions in their clonal read percentage burden over their treatment period. Conclusions: TCR-Seq of the TRG and TRB genes affords better resolution of T-cell clones and permits tracking of clones over time. On a further subgroup analysis of 9 pts from our cohort of IVIG-treated pts, we found that pts who exhibited monoclonality as established by TCR-Seq were more likely to respond to IVIG, with more significant erythroid and hemolytic responses, associated with a consequential (45+ months) longer treatment duration. Thus, TCR-Seq appears to be a superior option to PCR-based TCR gene rearrangement assays to reliably identify T cell clones in pts with MDS, and may be a useful biomarker to prospectively identify a subset of pts that can respond to IVIG. Further studies are ongoing to test this hypothesis. Disclosures Navada: Onconova Therapeutics Inc: Research Funding. Silverman:Onconova Therapeutics Inc: Patents &amp; Royalties, Research Funding; Medimmune: Research Funding; Celgene: Research Funding.

Leukemia Cutis in a Patient with Rare Indolent T-Prolymphocytic Leukemia - A Case Report and Review of the Literature

Abstract Introduction/Objective T-cell prolymphocytic leukemia (T-PLL) is rare, comprising 2% of mature lymphocytic leukemias in adults. Clinical course is usually aggressive, however, 20-30% patients can have an indolent early phase. Most patients present with extensive disease with peripheral blood lymphocytosis, hepatosplenomegaly, and lymphadenopathy. T-PLL has a higher incidence in patients with ataxia-telangiectasia. Methods We present a case of a 67-year old man with history of somatic mutation of ataxia-telangiectasia gene (ATM) and multiple malignancies, including melanoma, skin and laryngeal squamous cell carcinomas, adrenal adenoma and spindle cell lung tumor (diagnosed on biopsy), who developed leukemia cutis during an indolent phase of T-PLL. Results Initial diagnosis of T-PLL was on routine complete blood count when patient had mild atypical lymphocytosis (5.5 x 109/L). Flow-cytometry immunophenotyping detected CD4 + 8 positive mature T-cells with no aberrant loss of T- cell antigens, and molecular studies confirmed clonal T-cell receptor beta and gamma gene rearrangements. T-PLL associated leukemia cutis was diagnosed on a leg skin nodule biopsy 10 months later. Subsequent bone marrow biopsy demonstrated low level involvement by T-PLL. The patient’s T-PLL followed an indolent trajectory for three years and treatment was withheld until symptomatic presentation. Rapid disease progression was heralded with emergence of widespread T-PLL leukemia cutis, rapidly increasing lymphocytosis, extensive lymphadenopathy, splenomegaly and increasing LDH levels. Conclusion Skin involvement is reportedly identified in 20% to 50% of T-PLL cases in some series. Skin manifestations can be heterogenous with a broad clinical differential. T-PLL associated leukemia cutis may not be recognized owing to the overall low incidence and in skin lesions appearing during an undiagnosed indolent early phase of T-PLL.We highlight the importance of accurate evaluation of non-specific skin lesions in early detection of T- PLL. Being aware of this diagnosis and early engagement in an interdisciplinary approach may allow for better outcomes of this aggressive malignancy.