A rapidly progressive painful skin lesion

A 48-year-old woman presented to our emergency department with fever and a severe painful erythematous and ecchymotic skin lesion on the third finger of the left hand, that rapidly evolved into haemorrhagic bullae with diffuse swelling and edema of all her left hand, associated with the onset of lymphangitis in her left arm and crescendo-like pain. She denied trauma or insect bite. Her past medical history was unremarkable, except for chilblains with no sequelae. She did not take any medication. She was not a smoker. Laboratory tests showed neutrophilic leucocytosis (WBC 15,000/mm3; N 14,500/mm3), a slight thrombocytopenia (139,000/mm3), elevated C-reactive protein (12 mg/dL, normal value <0.5), increased procalcitonin (1.3 ng/mL, normal value < 0.5) and transaminases (AST 64 U/L; ALT 70 U/L, normal value 0-31). HIV was excluded.