This young man developed a small papule which progressed to a nodule and ulcer over several months. He has a history of inflammatory bowel disease, an illness often associated with pyoderma gangrenosum. Histologically, I find this diagnosis unfullfilling as the dermatopathologist often can only say "yes..it could be". Biopsy of the ulcer gives nonspecific secondary changes, and biopsy too far away may only yield normal skin or scarring/repair. Pyoderma gangrenosum is another member of the neutrophilic dermatoses with Sweet syndrome and cellulitis, among others. Clinical-pathologic correlation is required but can usually lead to the correct diagnosis.
This biopsy from the edge of the ulcer shows many changes secondary to ulcer formation. There is a brisk inflammatory infiltrate and neovascularization near the ulcer bed. A dense neutrophilic infiltrate is present in this area and extends away from the ulcer.