When panniculitis becomes lymphoma: Timely diagnosis and treatment of a subcutaneous panniculitis-like T-cell lymphoma hiding in plain sight

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare form of cytotoxic cutaneous T-cell lymphoma that is typically localized to the subcutaneous adipose tissue and presents with associated constitutional symptoms. This is a unique dermatopathological neoplasm, characterized by peri-eccrine atypical lymphocytic infiltrates extending into subcutaneous fat, expressing cytotoxic T-cell phenotype along with cytotoxic granule-associated proteins, in addition to a high Ki-67 proliferation index. This case report illustrates the characteristic clinical features, diagnostic challenges, histopathological findings, and successful therapeutic management of SPTCL in a young adult female.