Granulomatous pyoderma gangrenosum: two unusual cases showing necrotizing granulomatous inflammation.

We present two cases of pyoderma gangrenosum (PG) with unusual histopathological findings. The main histopathological feature of PG is usually massive neutrophilic infiltration; the neutrophil is thus the cytologic hallmark of PG. The occurrence of vasculitis is controversial. In our patients, in contrast, biopsy specimens revealed extensive granulomatous inflammation with massive tissue necrosis throughout the entire dermis and subcutaneous tissue and vascular involvement simulating many other granulomatous diseases. However, there was no evidence of systemic disease. Our cases may therefore represent a histopathologically distinct subset of PG.