Pseudomonas aeruginosa infection mimicking erythema annulare centrifugum

A 3-year-old girl receiving chemotherapy for acute lymphocytic leukaemia developed a rapidly expanding red annular plaque on her thigh, initially without signs of systemic toxicity or local pain. Subsequently she developed Pseudomonas aeruginosa sepsis and purpura at the leading edge of the plaque. Skin biopsy showed an extensive necrotizing vasculitis with numerous Gram-negative bacilli in the blood vessel walls. In immunocompromised individuals, skin biopsy and culture of cutaneous lesions for bacteria and fungi should be considered even in the absence of signs of systemic toxicity or multiple lesions.