We report a case of a 2-year-old female who presented with bilateral progressive proptosis, visual loss, nasal obstruction, and breathing difficulty. Magnetic resonance imaging revealed a large sino-orbital mass that was extending to the orbital apex and skull base. An initial diagnosis of rhabdomyosarcoma was made elsewhere on the basis of the presence of round and spindle cell tumor. Subsequent biopsy with immunohistochemical staining was positive for nuclear staining with β-catenin, shifting the diagnosis to a myofibroblastic tumor, favoring desmoid-type fibromatosis. With image guidance, near complete excision of tumor was performed by a multidisciplinary team, while respecting danger zones such as the skull base and the optic nerve. Following a recurrence over 2 months, additional excision was performed with a 6-month treatment of methotrexate and vinblastine. Desmoid tumor is a rare form of soft tissue tumor uncommonly seen in the orbital area. Although benign, it is known to be recurrent and infiltrative. Few data are known and further information will aid in the management of these tumors.
Keywords: Deep fibromatosis; desmoid tumor; pediatric sino-orbital tumor.