A cutaneous presentation of a common condition

A 25 year old woman was reviewed on the ward by the dermatology team for persistent, painful intertriginous skin erosions beneath both breasts and in both groins. She had been admitted over a month ago with cellulitis around the erosions, which initially responded to intravenous antibiotics but needed several repeat courses owing to recurrence.

Crohn’s disease had necessitated a total colectomy at age 18 years. She also had severe learning difficulties and behavioural problems.

She could not tolerate topical treatments. The only regular drugs at admission were mesalazine 1500 mg daily and clozapine. High dose oral corticosteroids before colectomy caused a marked transient psychosis and she had not received further systemic corticosteroids since.

She was obese with deep sloughy linear erosions demonstrating the “knife-cut” sign beneath the abdominal apron, in the inguinal creases, and under both breasts (fig 1⇓). She also had an eroded ulcer in her right labium majus.

Multiple skin swabs were negative for bacterial, candidal, and herpes simplex virus (HSV) infections. Initial skin biopsy showed only non-specific scarring in the dermis, but a deeper one showed non-caseating granulomatous inflammation.