Intraosseous Collagenous Fibroma (Desmoplastic Fibroblastoma) Involving Maxillary Bone

The collagenous fibroma (desmoplastic fibroblastoma) is a rare benign soft tissue tumour that can occur in the oral mucosa; intraosseous lesion is uncommon. A 43-year-old woman showed a well-circumscribed intraosseous radiolucency involving the maxillary edentulous area corresponding to 22 and 23 teeth. On intraoral examination, the edentulous ridge was covered by normal oral mucosa. The patient underwent an excisional biopsy and histopathological analysis revealed a tumour composed of spindle to stellate shaped cells scattered within a myxocollagenous stroma with invasion of skeletal muscle. The collagen bands showed strong positivity for Masson’s trichrome and the tumour cells showed focal positivity for HHF-35 and α-smooth muscle actin. The diagnosis was intraosseous collagenous fibroma according to both clinical and histopathological patterns. The patient was followed up for six months and there were no signs of recurrences. We report the second case of oral intraosseous collagenous fibroma and a critical review of English literature of the tumour in oral cavity.