Ulcerative Colitis Diagnosed through Evaluation of Underlying Diseases in a Pyoderma Gangrenosum Adolescent without Gastrointestinal Symptoms.

Pyoderma gangrenosum (PG) is a rare, non-infectious, neutrophilic dermatosis characterized by painful ulcers with indistinct borders and peripheral erythema. The diagnosis of PG requires the exclusion of other causes of similar appearing skin manifestations, including vasculitis and infections. The pathogenesis of PG is not clear; however, dysregulation of the immune system has been suggested in previous studies. More than half of the PG patients have underlying diseases; the most common being inflammatory bowel disease (IBD). The progression of PG in IBD patients is seen after the onset of IBD, usually during its exacerbation. On the other hand, PG may follow a course independent of the intestinal disease. We present a case of an 18-year-old young male with PG that presented before being diagnosed with ulcerative colitis as an associated condition. He had a painful ulcerative lesion on his right shin with no previous gastrointestinal symptoms. This case suggests that investigating for underlying disorders is essential in PG patients despite the lack of symptoms other than the skin lesions.