Case Studies

 Case 10.12 Polyarteritis nodosa

A 64-year-old man developed diplopia due to a right sixth nerve palsy, lethargy, weight loss and skin lesions on the right leg which were thought to be erythema nodosum. Six weeks later, he presented with aches and pains in his shoulders, which his doctor thought were due to polymyalgia rheumatica. He improved dramatically on steroids but unfortunately they had to be withdrawn because of hypertension. On investigation, he had an ESR of 104mm/h, a polymorphonuclear leucocytosis and some proteinuria (1.5g/24h) with occasional granular casts. Biopsy of a skin lesion showed non-specific changes. A renal biopsy was normal. No diagnosis was possible.

Four weeks later, he developed profound malaise with fever, marked muscle weakness and anaemia. His haemoglobin was 77g/l with a CRP of 70mg/l, a negative direct Coombs' test and a reticulocyte count of 5.4%. His blood urea, serum creatinine and creatinine clearance were normal, as was his serum creatine kinase level. His ANA, dsDNA binding and antineutrophil cytoplasmic antibodies (ANCA) were negative, with normal C3 and C4 complement levels. Biopsy of an affected calf muscle showed a florid arteritis. All the medium-sized arteries showed reduction of their lumens or complete occlusion. On the basis of this muscle biopsy, a firm diagnosis of polyarteritis nodosa was made. The patient was started on 60mg of prednisolone per day. Over the next few days his temperature fell and his symptoms improved.