The presenting manifestations of subcutaneous panniculitis-like T-cell lymphoma and T-cell lymphoma and cutaneous γδ T-cell lymphoma may mimic those of rheumatic diseases: a report of 11 cases.

This study aims to investigate the association between subcutaneous panniculitis-like T-cell lymphoma (SPTCL) or cutaneous gamma/delta T-cell lymphoma (CGDTCL) and a variety of manifestations that mimic autoimmune disorders. A retrospective chart review was made for 11 patients who were initially diagnosed as autoimmune diseases but finally turned out to be SPTCL or CGDTCL. Eleven patients were initially diagnosed with erythema nodosum, nodular panniculitis, lupus erythematosus profundus, systemic vasculitis, dermatomyositis, or pyoderma gangrenosum. The interval between presenting symptoms and the diagnosis of lymphoma was 17.5 (range, 3-84)  months on average. Nearly all cases had multiple subcutaneous nodules or plaques that were most commonly distributed on the extremities and trunk. Fever was the primary accompanying sign (9/10), followed by lymphadenopathy (6/11), splenomegaly (5/11), and hepatomegaly (3/11). Two patients developed hemophagocytic syndrome. A total of 26 biopsies involving multiple anatomic locations were performed. Antirheumatic therapy including steroids and immunosuppressive agents administered before the identification of T-cell lymphoma revealed unsustainable therapeutic effect. In contrast, seven cases gained partial response after chemotherapy, while the remaining four cases died with disease progression and disease-associated severe infections. SPTCL and CGDTCL are rare and heterogeneous which may resemble those rheumatologic diseases that are characterized by inflammation involving the skin or subcutaneous fat tissue. The diagnosis relies on the constellation of disease-specific pathologic, immunophenotypic, and T-cell receptor gene rearrangement tests. In the context of an ambiguous clinical picture demonstrating inconsistency with the initial diagnosis of benign autoimmune diseases, repeated excisional biopsies of the subcutaneous lesions may be required to uncover the underlying lymphoma.