Pain, purpura and curly hairs

A 43-year-old man was referred to dermatology after presenting to the accident and emergency department with leg pain, swelling and rash. The purpuric rash had developed over the preceding 4 weeks. He had no history of trauma or recent illness, and was otherwise well at presentation. He had a history of schizoaffective disorder that was being treated with olanzapine, and he lived alone in sheltered accommodation. On direct questioning, he also complained about oral discomfort and tooth loosening over the previous few weeks, as well as leg swelling and bone pain. On physical examination, there were large areas of purpura seen on the anteromedial thighs and pitting oedema to the mid calves bilaterally (Fig. 1). There was widespread perifollicular haemorrhage, and the hairs on the patient’s legs were corkscrew in shape (Fig. 2). The skin was otherwise dry, and there was diffuse hyperkeratosis affecting the dorsa of the feet. In the mouth, there was redness of the interdental papillae. Blood tests showed; haemoglobin 11.4 g/dL (normal range 13.0–18.0 g/dL), white blood cell count 14 (4– 11 9 10/L), neutrophils 11.5 (1.5–7 9 10/L), sodium 128 mmol/L; (135–144 lmol/L), creatinine 102 lmol/L; 90–120 mmol/L) and bilirubin 30 (1– 22 lmol/L), and normal results for platelets 326 (150– 400 9 10/L) and potassium 4.8 (3.5–4.9 mmol/L). Liver function tests, coagulation parameters, autoimmune profile, vasculitic screen, urinalysis and chest radiography were normal. Histological findings