Arthritis associated with hairy cell leukaemia.

We report the case of a 65-year-old patient with a 15-year history of intermittent asymmetrical oligoarthritis, who subsequently developed splenomegaly, lymphadenopathy, and episodic leucopenia and thrombocytopaenia. Investigations revealed hairy cell leukaemia, and 'hairy cells' were detected in the synovial fluid. No other cause for this arthritis was found, and we consider the blood dyscrasia to be the likely cause. This case demonstrates a hitherto unreported association between arthritis and hairy cell leukaemia.