Derm Dx: Painful skin lesions in a 48-year old woman with an upper respiratory infection

A 48-year-old woman with a high-grade fever, conjunctivitis and an upper respiratory infection presents with painful red skin lesions that appeared suddenly on her arms, neck and face. The bumps spread and grew forming tender, painful plaques, some of which blistered and ulcerated.

The patient complains of tiredness, achy joints and headaches. Labs reveal elevated C-reactive protein levels and leukocytosis ...