Pruritic red papules on the knees

Abstract

Conflict of interest: none declared. An 85‐year‐old man was admitted for intermittent claudication and rapidly deteriorating renal function. He was referred to our department for evaluation of a 2‐month history of pruritic red papules on the legs. He was a heavy smoker and had a 5‐year history of hypertension and renal insufficiency. Clinical examination showed small red papules with pruritus on both knees and the pretibial regions (Fig. 1). Slight cyanosis was observed on both third toes. Bilateral pedal arterial pulses were not palpable and there was vascular murmur on abdominal auscultation. Imaging studies including magnetic resonance imaging and angioultrasonography revealed multiple arteriosclerosis and soft plaques within the aortic artery and renal arteries. Laboratory tests showed eosinophilia (21.6%, 1814/μL) and raised serum creatinine (5.8 mg/dL, normal 0.6–1.1). ... A needle‐shaped cleft was found within a small vessel at a dermal‐subcutaneous junction. Granulomatous reaction consisting of foreign body giant cells, macrophages and eosinophils was observed around the cleft (Fig. 2). CD68, which is a marker for histiocytes, was positive in cells surrounding the cleft.