question

What is the diagnosis?

The picture shows the typical 'cobblestone mucosa' of Crohn's disease with isolated areas of normal mucosa surrounded by deep ulceration (ulcerative colitis does not result in such deep ulceration).

What is the diagnosis?

This is pyoderma gangrenosum.

Estimates of the prevalence in inflammatory bowel disease (IBD) range between 2% and 5%. It tends to be associated with colonic involvement and is perhaps slightly more common in patients with UC. The clinical presentation here favours a diagnosis of UC over Crohn's.

It is most common on the lower limb and in scars or sites of previous trauma. It is treated by immunosupression. Lesions begin as small papules or pustules before breaking down into an ulcer. Ulcers are deep with a violaeceous border and and edge which overhangs the ulcer base.