A 61 year old white homosexual man complained of profound fatigue, proximal lower extremity weakness, myalgias, and fever of two days' duration. He also complained of a worsening rash over his proximal upper extremities, trunk, and back for the past month. Two months earlier he had been diagnosed with seronegative rheumatoid arthritis when he presented with bilateral hand and wrist pain. He denied cough, shortness of breath, photosensitivity, Raynaud's phenomenon, dry mouth or eyes, recent travel, pets, morning stiffness, penile discharge, or genital ulcers. He tested HIV negative three months before admission. His past medical history was significant for hypertension, gastro-oesophageal reflux disease, and obstructive sleep apnoea. He had been taking prednisone 15 mg and cimetidine 400 mg daily.

On examination, the patient looked acutely ill and uncomfortable. He was febrile at 102.4°F, his blood pressure was 148/80 mm Hg, and his pulse was 90 beats/min. He had confluent erythematous and purpuric plaques on his back, anterior trunk, and proximal upper extremities (see fig 1); some were in a polycyclic arrangement but without scale. No muscle tenderness or weakness was detected. There was no appreciable arthritis or synovial thickening. He had a II/VI systolic murmur throughout his precordium without radiation. The remainder of his physical examination was without abnormalities.

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Figure 1

Purpuric plaques.

The initial evaluation is listed in box 1. A skin biopsy showed superficial and deep perivascular infiltrates with extensive interface damage. Immunofluorescence revealed strong granular C3 and trace granular IgG and IgM at the dermal-epidermal junction.