Schnitzler's syndrome: a diagnostic conundrum.

A 63-year-old man was referred to the rheumatology unit with myalgia, arthralgia and a widespread rash. He was investigated for rheumatological disease; however, this did not yield any specific findings. His symptoms were attributed to statin use and newly started antihypertensives which were promptly discontinued. There was some subsequent improvement in his symptoms so he was discharged. He re-presented 3 years later with pelvic bone pain which had responded to a course of oral steroids started by the general practitioner, who was treating a presumed diagnosis of polymyalgia rheumatica. However, MRI of the pelvis showed bone marrow oedema and the diagnosis was changed to mastocytosis. He did not tolerate or respond to initial treatment. It was not until a second opinion was sought from the dermatologists that the diagnosis of Schnitzler's syndrome was made and treatment with anakinra (an interleukin-1 receptor antagonist) was started with almost complete resolution of his symptoms.