Abstract

Gamma-delta T cell lymphoma (GD-TCL) is a rare and aggressive malignancy characterized by the expression of the gamma-delta, rather than alpha-beta, T cell receptor (TCR). This entity occurs in cutaneous sites and is thought to arise from resident epithelial gamma-delta T cells. We present a case of GD-TCL in a 70 year old man. The patient described a one-year history of skin lesions and weight loss. The lesions appeared as both subcutaneous nodules and ulcerating plaques that began on the distal lower extremities and progressed to diffusely involve the extremities and to focally involve the trunk. Excisional biopsy demonstrated a dermal and subcutaneous population of atypical lymphocytes with a moderate amount of pale cytoplasm, angulated hyperchromatic nuclei, and frequent mitotic figures. The cells encircled vascular and adnexal structures and densely infiltrated subcutaneous adipose tissue. The overlying epidermis was atrophic but lacked significant lymphocyte epidermotropism. The atypical lymphocytes stained positively for CD2, CD3, and TCR delta (H-41), distinguishing the lesion from subcutaneous panniculitis-like T cell lymphoma. Consistent with the cytotoxic gamma-delta phenotype, the cells expressed TIA and granzyme B. Staining for CD4, CD5, CD7, CD8, CD10, CD20, CD21, CD30, ALK-1, TCL-1A, PD1, and BF1-TCR was negative. Chromogenic in situ hybridization did not detect Epstein-Barr virus. Notably, the patient displayed pancytopenia, lymphadenopathy, and splenomegaly. Flow cytometry of peripheral blood was negative, but no additional tissue biopsies were performed. While a primary cutaneous GD-TCL was favored, secondary involvement by a systemic process could not be excluded. We present this case to demonstrate the classic clinical, histologic, and immunophenotypic features of this rare and aggressive entity and to highlight key differential diagnostic considerations.

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