Collagenous fibroma (desmoplastic fibroblastoma) of the orbital rim.

A 40-year-old woman with left periorbital swelling for 1 month presented without diplopia or change in vision. Imaging studies revealed a 1-cm mass at the frontozygomatic junction at the orbital rim with slight bony erosion and spiculation. The lesion was applied to the periosteum and was excised along with a portion of the bony orbital rim. Histopathology revealed elongated and stellate fibroblasts within a dense collagenous matrix. Vimentin and Masson trichrome staining was consistent with a collagenous fibroma, a rare tumor that has, only once before, been reported in the orbit in the lacrimal fossa region. The current collagenous fibroma arose from the periosteum to grow exophytically, causing minimal bone changes. A literature review shows that this condition predominantly affects middle-aged and older adults rather than children.