Chronic immunity-driven polyarthritis in hairy cell leukemia. Report of a case and review of the literature.

Hairy cell leukemia can be responsible for polyarthritis due either to leukemic infiltration or to immunity-drive inflammation. The second variant can antedate or post-date the clinical onset of leukemic symptoms and usually presents as rheumatoid arthritis, more rarely as lupus or scleroderma. The presence of hairy cells in the joint fluid does not rule out autoimmune polyarthritis. The main differential diagnoses are Felty's syndrome and large granular lymphocyte leukemia. We report a case of hairy cell leukemia with seropositive rheumatoid arthritis.