[Fibro-osseous pseudotumor of the digits: One of USP6-related fibroblastic/myofibroblastic tumors]. / La pseudotumeur fibro-osseuse des doigts : une tumeur fibroblastique/myofibroblastique liée à USP6.

Fibro-osseous pseudotumor of the digits is a benign tumour closely related to myositis ossificans. It is a rare lesion seldom reported in the literature. We report the case of a 33-year-old woman with lancinating pain in the first phalanx of the second finger of the right hand, associated with inflammation. The histopathological examination of the surgical excision biopsy of the lesion revealed a spindle-shaped proliferation within a sclerosing, hyaline, and osteoid stroma. In our observation, immunohistochemistry and molecular biology are the main elements that helped to establish the diagnosis and eliminate the various differential diagnoses, despite a non-specific histopathological aspect.