Gamma-delta (γδ) T-cell lymphoma - another case unclassifiable by World Health Organization classification: a case report

Differentiating reactive and neoplastic gamma-delta (γδ) T-cell expansions in the peripheral blood and bone marrow

The clinical and immunophenotypic attributes of reactive γδ T-cell expansions are less well characterized than their malignant counterparts, which can pose diagnostic challenges. This study aims to investigate the characteristics and long-term clinical outcomes of reactive γδ T-cell expansions. A retrospective review was performed to identify patients with expanded γδ T-cell population (>15% of T-cells) by flow cytometry in peripheral blood and/or bone marrow specimens over a 17-year period. The cases were divided into reactive and malignant categories and their clinical and immunophenotypic findings were compared. Clinical follow-up was performed. 97 patients were identified including 19 malignant and 78 reactive cases with a variety of underlying conditions. The median absolute γδ T-cell count and median percentage of γδ T-cells per total T-cells were significantly lower in reactive vs. malignant cases (p = 0.0001 and p < 0.00001, respectively). Reactive cases showed more frequent brighter surface CD3 expression (87.1% vs. 42.1%; p < 0.0001), no discrete loss of CD7 (0% vs. 36.9%; p < 0.0001), less frequent lack of CD5 (25.7% vs. 42.4%; p < 0.0001), and no homogeneous CD56 expression (0% vs. 31.6%; p > 0.0001) as compared with malignant cases. Upon long-term follow-up, none of the reactive cases showed clinical evidence of malignant evolution. Reactive expansions of γδ T-cells can be seen in a variety of conditions including hematologic neoplasms, autoimmune and post-transplant states, and infections. Such cases have significantly lower γδ T-cell counts and percentages and no discrete loss of CD7. Lack of CD5 on its own is not an indication of immunophenotypic aberrancy in γδ T-cells. Upon long-term clinical follow-up, such reactive expansions show no evidence of evolution to γδ T-cell malignancies.

Nck1 regulates the in vitro development of human regulatory T cells through AKT pathway

T cell receptor (TCR) signalling is crucial in determining the fate of thymocyte differentiation in the thymus. The high-avidity interaction between TCR and self-peptide-MHC complexes induces development of regulatory T cells (Tregs), lineage commitment for which is controlled by expression of transcription factor Forkhead box P3 (FoxP3). The non-catalytic region of the tyrosine kinase (Nck) comprises two members, Nck1 and Nck2, with Nck1 playing a dominant role in TCR-mediated T cell activation and function. Nck's role, while established in thymocyte development, remains unelucidated in development of Tregs. In this study, we aimed to determine the function of Nck1 in the in vitro development and differentiation of human thymocytes. Human thymocytes were transfected with shRNA plasmid to silence Nck1 expression. The number of FoxP3+ Tregs decreased noticeably in Nck1 knockdown thymocytes after co-cultivation with myeloid dendritic cells (mDCs) and thymic epithelial cells for 14 days. Furthermore, decreased phosphorylation of AKT and FoxO1 was observed in Nck1-silenced thymocytes, in association with reduced FoxO1 nuclear localization. Taken together, these findings identify the pivotal role of Nck1 in Treg development.

Secondary Gamma-Delta T-Cell Lymphoma Not Otherwise Specified (NOS) From Chronic Immunosuppression

Herein, we present the case of a 63-year-old female with a history of Behçet’s disease managed with long-term prednisone and azathioprine who initially presented for symptomatic anemia, which progressed to pancytopenia with neutropenic fever. Initial workup ruled out infectious etiologies but was indeterminate for immune-mediated or neoplastic causes. Bone marrow biopsy demonstrated a CD8+ gamma-delta T-cell neoplasm; however, imaging and skin biopsy pathology did not support hepatosplenic or cutaneous lymphoma involvement. By the 2017 World Health Organization (WHO) classifications, these findings were defined as gamma-delta peripheral T-cell lymphoma, not otherwise specified (NOS). This is suspected to be secondary to chronic immunosuppression from long-term steroid and azathioprine use. The patient was treated with one cycle of the EPOCH chemotherapy regimen ((etoposide, vincristine, cyclophosphamide, doxorubicin, and prednisone), but the treatment course was complicated by an angioinvasive fungal infection and the patient subsequently transitioned to symptom-focused therapy in a hospice facility.

A Challenging Case of Gamma Delta T-Cell Lymphoma with Precursor T-Cells and Marked Eosinophilia: A Case Report

Gamma-delta (γδ) T-cell lymphomas are very rare and aggressive neoplasms. We describe here a challenging case of γδ T-cell neoplasm composed of γδ mature T-cells and γδ precursor T-cells with marked eosinophilia that is inapplicable to the current 2016 World Health Organization (WHO) classification. A 3-year-old female child who was presented with fever and marked leukocytosis. Peripheral blood smear showed marked lymphocytosis, marked eosinophilia, neutrophilia, monocytosis, and 5% circulating blasts. CT scan showed anterior mediastinal mass, lymphadenopathy, and hepatosplenomegaly. The patient underwent a bone marrow examination and a biopsy taken from the mediastinal mass. Peripheral blood and bone marrow findings were consistent with a γδ T-cell neoplasm with increased blasts and eosinophilia. The patient was sequentially treated with imatinib (tyrosine kinase inhibitor), acute lymphoblastic leukemia protocol (BFM 2009) then shifted to lymphoma protocol (LMP 96). In conclusion, we report a unique rare case of γδ T-cell neoplasm with a combination of mature and immature γδ T-cells and eosinophilia that is inapplicable to the current 2016 WHO classifications. This case raises a challenging concept of a mature T-cell lymphoma arising in an immature T-cell neoplasm. It also highlights the need to target all neoplastic components to eradicate the disease.

Silent T-cell receptor cutaneous T-cell lymphoma associated to a clonal plasma cell proliferation

Within T-cell lymphomas (TCL) there are 2 entities expressing gamma-delta TCR: hepatosplenic gamma-delta T-cell lymphoma (HSGDTL) and the primary cutaneous gamma-delta T-cell lymphoma (PCGDTL). PCGDTL is a rare form of Tcell lymphoma with specific tropism for skin that have a dismal prognosis. Although even rarer, there have been reports of TCL with loss of expression of the TCR, which have been termed peripheral TCL TCR-silent type. We report the case of a cutaneous TCR-silent type lymphoma associated to a clonal plasma cell proliferation with an ominous outcome that led to a lot of discussion in its classification. Due to the aggressiveness of the disease and the scant evidence about therapy in this strange entity the outcome was fatal. We report a unique case of a TCR-silent cutaneous TCL with an exceptional histopathology, prolonged clinical evolution and a subsequent plasma cell clonal expansion.

18F-FDG PET/CT findings in hepatosplenic Gamma-Delta T-cell lymphoma: case reports and review of the literature

Hepatosplenic Gamma Delta T cell lymphoma (γδHSTL) is a rare, highly aggressive, and rapidly lethal T cell lymphoma which manifests ¹⁸F-FDG PET/CT findings that can mimic benign conditions. Patients with γδHSTL present with unexplained symptoms of a hematologic malignancy like the B symptoms of lymphoma including weight loss, fevers, and night sweats, as well as, splenomegaly and hepatomegaly. Thrombocytopenia, anemia, or neutropenia are also common due to spleen, liver and bone marrow involvement. The peripheral blood, however, typically does not show abnormal T cells. The clinical and ¹⁸F-FDG PET/CT findings are presented for 3 patients with γδHSTL. Patients with γδHSTL may have a normal ¹⁸F-FDG PET/CT or an ¹⁸F-FDG PET/CT with any combination of the three findings: splenomegaly with intense FDG uptake; hepatomegaly with increased FDG uptake; and diffuse, increased FDG uptake in the bone marrow. Importantly, lymphadenopathy is usually absent, and most patients show morphologically normal lymph nodes with normal FDG uptake. Due to the aggressive nature of the disease, γδHSTL is a critical diagnosis to consider in patients who present with clinical signs of suspected hematologic malignancy and variable ¹⁸F-FDG PET/CT findings. The absence of lymphadenopathy and normal FDG uptake in lymph nodes are typical pertinent negative findings that differentiate γδHSTL from other lymphomas. A bone or liver biopsy is frequently necessary to establish the diagnosis and should be recommended.