Neuropathy and a rash

A 26 year old woman was referred to dermatology with a one year history of a rash on her lower legs, abdomen, and arms, and a six month history of paraesthesia in her right hand and left foot. She had no history of fatigue, weight loss, fever, or arthralgia.

There was palpable retiform erythema and broken livedo on her abdomen, arms, and legs (fig 1). She had reduced sensation to light touch in the right ring and little fingers, the lateral palmar and dorsal hand, the left lateral calf, and the dorsum of the left foot. She had a feeling of clumsiness in her right hand that caused her difficulty with writing, but there was no weakness.

Blood tests were normal, including a full autoimmune screen. Skin biopsy showed medium vessel vasculitis with fibrinoid necrosis. Electromyography showed sensory damage in the right ulnar nerve and asymmetrical superficial sensory damage in the peroneal nerve, with the left side being affected to a …