Necrotizing fasciitis as the clinical presentation of a retroperitoneal abscess.

Infections of the retroperitoneal space may present with insidiously vague symptoms and non-specific clinical signs. We report a case of a retroperitoneal abscess presenting as necrotizing fasciitis of the thigh from direct spread over the iliac crest. In cases of necrotizing fasciitis of the thigh with no obvious source, an intra-abdominal nidus of infection may be considered.