Acute multifocal skin necrosis: synergism between invasive streptococcal infection and cocaine-induced tissue ischaemia?

A 30-year-old pregnant woman with full thickness skin necrosis following parenteral abuse of cocaine and heroine is described. Three lesions occurred simultaneously on the trunk and right knee subsequent to an abscess on the left thigh from which S. pyogenes group A and S. aureus were isolated. Histology revealed necrotic subcutaneous tissue with obliterated vessels and a mixed inflammatory infiltrate. The sequence of events suggests a synergism between the effects of bacterial proteases and cocaine-induced impairment of soft tissue perfusion. In the present case, this synergism may have been further enhanced by decreased cocaine tolerance during pregnancy.