[Deep-seated granulomatous pyoderma gangrenosum: A novel variant?]

We report an extremely rare case of pyoderma gangrenosum with the clinical features of pyoderma gangrenosum but with unusual histopathological findings and deep massive granulomatous infiltration through the dermis.

A 15-year-old girl presented with a two-month history of deep ulcers on the lower legs and forehead. She also presented abdominal pain with diarrhea and vomiting that disappeared after symptomatic treatment. Histology showed extensive granulomatous infiltration in the dermis and hypodermis and a micro-abscess in the dermis. An abdominopelvic CT scan revealed peritoneal fluid and tissue formation in a lateral carotid cave (6.56 cm/4.56 cm). Colonoscopy was normal. The patient was treated with oral prednisone, resulting in resolution of the problems of cutaneous lesions, peritoneal fluid and tissue formation.

Our case involves a rare presentation of pyoderma gangrenosum (PG) inconsistent with any of the four clinical variants of PG and characterized histologically by the presence of deep granulomas in the dermis and hypodermis. Despite the atypical clinical presentation and unusual histopathological findings, PG seemed the most likely diagnosis after infectious diseases had been ruled out; the good outcome achieved with oral corticosteroids supported our diagnosis.