St. Peter's Hospital, Chertsey, Surrey KT16 OPZ

A 56-year-old man with hairy cell leukaemia developed classic polyarteritis nodosa in 1980, 11 years after the initial diagnosis of leukaemia. The association of two uncommon disorders may have pathogenetic implications. HAIRY cell leukaemia (HCL) is a rare disease characterized by circulating mononuclear cells with prominent cytoplasmic projections, pancytopenia and splenomegaly. The precise nature and origin of the hairy cell remains controversial. The course of the disease is often chronic (median survival six years) and the most frequent complication is infection (1). Four cases of HCL complicated by polyarteritis nodosa have been described (2). We report a further case of HCL who subsequently developed classic polyarteritis nodosa. Case report In 1969 a 45-year-old man presented with a petechial rash and hepatomegaly. The haemoglobin was 11.2 g/dl, white blood count 10 x 109/l (blast cells 96%) and platelets 24 x 109/l. Bone marrow showed complete replacement by abnormal cells considered to be blasts. A diagnosis of acute leukaemia was made by four haematologists. Chemo-therapy using daunorubicin and cytosine arabinoside led to a remission and smal