Histopathologic features of superficial granulomatous pyoderma.

Study of the histopathologic pattern of 28 cases of superficial granulomatous pyoderma demonstrated an ulcerative, verrucous pyoderma of the superficial dermis. Focal abscesses in the subepidermis or dermis were juxtaposed with granuloma formation and plasma cell inflammation. Hemorrhage and granulation tissue were present. The clinical lesions are indolent, and this feature is confirmed by chronic inflammatory elements, including sinus tract formation and focal fibrosis. Superficial granulomatous pyoderma must be added to the histologic differential diagnosis of the vegetative and ulcerative granulomas: blastomycosis, tuberculosis verrucosa cutis, and bromoderma.