Collagenous fibroma (desmoplastic fibroblastoma) of the oral cavity.

Collagenous fibroma (desmoplastic fibroblastoma) is a distinctive yet uncommon fibrous soft tissue tumor. These tumors are rather nondescript in their morphological appearance and have been diagnosed as fibromas or some other benign mesenchymal lesions for years. The most common sites are the upper extremities, followed by the lower extremities. Rare lesions arise in the head and neck region. We report a rare case in the oral cavity and present its unique histopathological features (central fat entrapment) besides others, and diffusely strong vimentin immunopositivity.