Subcutaneous panniculitis-like T-cell lymphoma misdiagnosed as lupus erythematosus panniculitis

We report a case of subcutaneous panniculitis-like T-cell lymphoma (SPTCL), associated with macrophage activation syndrome, mimicking a lupus erythematosus panniculitis (LEP). A 29-year-old woman presented with high fever, general malaise, nausea, vomiting, and subcutaneous nodules and ulcerating lesions located on the lower extremities. The histopathology showed an infiltration of the panniculus, mostly involving fat, and periadnexial and perivascular structures consistent with lymphocytic lobular panniculitis (LLP). LLP is a shared feature of LEP and SPTCL. The immunophenotyping of the cell infiltrate was crucial for a correct diagnosis.