Fatal subcutaneous panniculitis-like T-cell lymphoma with interface change and dermal mucin, a dead ringer for lupus erythematosus.

We report a 48-year-old man who presented with ulcerated plaques and nodules of the lower extremities. Skin biopsies revealed a dense lymphocytic infiltrate involving the dermis and the subcutis in a lobular and septal pattern. No overt cytological atypia was present. Notably, several features resembling lupus erythematosus were present, including vacuolar interface change and abundant dermal mucin deposition. The patient developed pulmonary nodules, and a lung biopsy showed a perivascular and interstitial lymphoid infiltrate without overt atypia. The cutaneous and pulmonary lymphoid infiltrates showed similar immunohistochemical profiles: CD3(+) CD4(-) CD8(+/-) CD56(+). Monoclonal rearrangements of the T-cell receptor gamma gene with similar migration patterns were identified from both locations. The patient developed fatal hemophagocytic syndrome, involving liver, spleen, lymph nodes, and bone marrow. This case is one amongst the rare reports of subcutaneous panniculitis-like T-cell lymphoma with systemic involvement.