All that is red is not cellulitis. Pyoderma gangrenosum.

Eur J Intern Med · 2014

case_report · Level V

Where this comes from

Abstract

A 60-year-old patient presented with progressive worsening, non-healing ulcer on her shin with surrounding erythema following a minor trauma and was treated with several antibiotics for presumed cellulitis with no improvement. A skin biopsy eventually suggested pyoderma gangrenosum and a colonic biopsy showed an underlying ulcerative colitis.