Subcutaneous Leukemia Cutis as the Initial Manifestation of CD23 Negative CLL/SLL in a Patient With Rheumatoid Arthritis on Chronic TNF-Alpha Inhibition.

Rheumatoid arthritis (RA) is a chronic, systemic, and autoimmune disease characterized by inflammation and pain in the joints. While RA and TNF-alpha inhibitors have historically been associated with an increased risk of lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is infrequently seen. CD23 negative CLL is rare. Extranodal manifestations of CLL/SLL are uncommon. While cutaneous involvement is among the more common extranodal manifestations, leukemia cutis is rare. Furthermore, subcutaneous leukemia cutis as the initial manifestation CLL/SLL is exceedingly uncommon. We describe a patient with longstanding RA on chronic TNF-alpha inhibition who presented with an isolated subcutaneous mass. Excisional biopsy demonstrated sheets of small, uniform, and mature lymphocytes with flow cytometric analysis noting a monoclonal B-cell population negative for CD23 expression but positive for CD5, CD19, CD20, CD38, kappa light chain, and CD200 expression. Further immunostaining was negative for cyclin-D1 and SOX11 and positive for CD43 and LEF1, overall consistent with CLL/SLL-induced subcutaneous leukemia cutis. While treatments for CLL/SLL-induced leukemia cutis vary, in this case, consolidative local radiation led to resolution of the remaining cutaneous lesion. Caution is advised when considering the use of TNF-alpha inhibitors in patients with a history of lymphoma.