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Case Reports

Abstract

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare primary cutaneous T-cell lymphoma with adipotropism characterized by infiltration of CD8+ T-cells expressing TCR α/β (βF1) and exhibiting cytotoxic immunophenotype. SPTCL is clinically indolent; thus, distinction between SPTCL and other aggressive cutaneous lymphomas like primary cutaneous gamma-delta T-cell lymphoma (PCGDTCL) is crucial for accurate patient prognostication. We present a case of SPTCL featuring elevated gamma-delta T-cells, posing a diagnostic challenge. The patient, a 26-year-old Asian woman with a history of hemophagocytic lymphohistiocytosis (HLH), presented with multiple ill-defined erythematous patches and hyperpigmented, palpable nodules on the extremities and trunks persisting for five months. Biopsy specimens revealed an atypical lymphoid infiltrate involving the subcutis, predominantly comprising atypical small-to-medium-sized lymphocytes rimming the adipocytes. Immunophenotypically, the lesional lymphocytes were CD3+/CD4-/CD8+/CD7+ T-cells expressing TIA1, granzyme B, and TCR βF1. They were negative for CD30 and EBER. CD123 failed to reveal aggregates of plasmacytoid dendritic cells. Intriguingly, an increased density of TCR δ+ T-cells was observed within the background infiltrate, with some neoplastic T-cells rimming adipocytes also exhibiting TCR δ expression. Molecular analysis revealed monoclonal gene rearrangements of TCRB and TCRG. Despite the unusual presence of an elevated TCR δ+ T-cell population, the overall clinical and histopathological findings, coupled with the lack of rapid disease progression, supported the diagnosis of SPTCL. Our case underscores the significance of increased gamma-delta T-cells in SPTCL. Failure to recognize this could lead to misclassification of such lesions as PCGDTCL, especially in patients presenting with HLH, emphasizing the need for thorough clinicopathologic correlation.