Subcutaneous panniculitic-like T-cell lymphoma: a red alert! The role of a vigilant histopathologist

Subcutaneous panniculitic-like T-cell lymphoma constitutes a distinctive clinicopathologic entity derived from cytotoxic T lymphocytes. A 25-year-old female presented with fever and skin lesions over the upper limb, lower limb and trunk since 2 years. On examination, there were multiple subcutaneous, tender, erythematous, poorly circumscribed indurated plaques and nodules on the upper limbs and lower limbs. Histopathological examination revealed subcutaneous fat displaying a predominantly lobular infiltration of atypical lymphoid cells. Characteristically, there was rimming of individual fat cells by the surrounding neoplastic lymphocytes. Immunohistochemical evaluation of the neoplastic lymphocytes showed CD3 and CD5 immunoreactivity and CD30 and CD20 negativity. A diagnosis of subcutaneous panniculitic T-cell lymphoma was made. SPTCL is a rare cytotoxic lymphoma that can be misdiagnosed as benign panniculitis due to similarities in clinical and histological features between the two entities and thus cause a diagnostic hindrance.