Abstract

Cutaneous T-cell lymphoma with the gamma-delta phenotype (CTCL-GD) is a diagnostic challenge. These tumors encompass primary cutaneous gamma-delta T cell lymphomas (PCGDTCLs), rare and aggressive tumors, and mycosis fungoides with the gamma-delta phenotype (GD-MF), still not well characterized. Even though MF accounts for approximately 50-60% of CTCLs, CTCL with gamma-delta immunophenotype is rarely reported in the literature. PCGDTCL has an unpropitious prognosis (31 months median survival rate), and urgent attention to convey an accurate diagnosis and appropriate therapeutic modality is warranted. We report a case of a 75-year-old female who presented with a solitary ulcerated erythematous mass on the left lateral distal anterior lower leg. No clinical lesions compatible with typical mycosis fungoides were present at the time of presentation. Microscopically, dense dermal atypical lymphoid infiltrates were identified with focal epidermotropism composed of large cells with hyperchromatic, irregular nuclei, and conspicuous nucleoli. Numerous mitosis and apoptosis were present. Immunohistochemical staining demonstrated a predominance of CD3-positive T-cells within the infiltrate. Most tumor cells were negative for both CD4 and CD8. CD30 highlighted a few cells. The atypical T-cells were positive for TCR delta, TIA1, and granzyme B and negative for TCR beta F1. T-cell receptor gene rearrangement studies by PCR were positive for a clonal T-cell population. Based on immunophenotype, the infiltrate was best categorized as CTCL-GD. Complete excision was pursued. Later, the patient developed a patch of CTCL-GD on arm. This is a unique case of CTCL-GD with clinical-pathological features of both PCGDTCL and GDMF that poses a diagnostic challenge, underscoring the difficulties of classifying these rare lymphomas.

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