Inverted verrucous carcinoma of the buttock mimicking abscess and gossypiboma: MR and pathologic correlation.

Verrucous carcinoma (VC) is an uncommon, low-grade variant of squamous cell carcinoma. Its benign histologic appearance and indolent course may lead to a delayed diagnosis. We report a rare case of an inverted verrucous carcinoma of the buttock presenting as a slow-growing subcutaneous lesion with a draining sinus and no exophytic component, clinically mimicking abscess and gossypiboma, with magnetic resonance imaging (MRI) and pathologic correlation. Biopsy of the lesional base is mandatory for accurate diagnosis. An enhancement pattern with a convoluted undulating appearance in a subcutaneous lesion displayed on MRI should raise a consideration of inverted VC in the differential diagnosis.