A 72-year-old woman was admitted because of a subcutaneous hip tumor. A biopsy specimen of the tumor showed a mixture of medium-sized and large lymphocytes infiltrating the subcutaneous fat tissue with a lobular panniculitis-like pattern--a histologic feature of subcutaneous panniculitic T-cell lymphoma (SPTCL). May-Grünwald-Giemsa-stained cytospin slides of freshly isolated neoplastic cell explants showed that the cells had the characteristics of large granular lymphocytes. Immunophenotypic analysis showed that the cells expressed CD56--a natural killer-associated antigen--as well as the cytotoxic T-cell phenotype CD3+ CD4- CD8+. Southern blot analysis revealed rearrangement bands of the TCR-beta chain gene. Chromosome analysis showed complex abnormalities including t(1;6) (q11; p21). The present case may shed some light on the origin and pathogenesis of SPTCL.