An Unusual Case of Intraosseous Desmoplastic Fibroblastoma (Collagenous Fibroma) of the Mandible.

Desmoplastic fibroblastoma (collagenous fibroma) is a rare, benign fibroblastic/myofibroblastic tumor that usually arises in the subcutaneous and intramuscular tissues. This tumor type has rarely been described to arise primarily in bones. This is a case of intraosseous desmoplastic fibroblastoma occurring in the mandible of a 35-year-old woman that was detected incidentally during a routine dental examination. The patient underwent surgical excision of the lesion. Microscopic examination demonstrated a paucicellular fibro-collagenous spindle cell neoplasm that showed a fibroblastic/myofibroblastic immunophenotype, consistent with desmoplastic fibroblastoma of the bone. The case presents an extremely rare intraosseous manifestation of an uncommon soft tissue tumor, highlighting its diverse anatomical and compartmental distribution.