Introduction:
Mammary-type extramammary myofibroblastoma (MTEM) is a rare mesenchymal neoplasm that is histologically and immunohistochemically identical to mammary myofibroblastoma.1 These extramammary neoplasms are composed of spindle cells, usually arise in the subcutaneous tissues, and traditionally express desmin, Smooth Muscle Actin (SMA), and CD34; they are closely related to spindle cell lipomas and cellular angiofibromas.2 Presentation outside of the embryological mammary crest is exceedingly rare, where involvement of extramammary sites classically includes the inguinal and groin area, vulva, perineum, and scrotum.1 There is a paucity of cases reporting head and neck MTEM following radiotherapy, and even more so concerning the nasal sinuses.3-7
We report a case of radiation induced MTEM requiring maxillectomy and ethmoidectomy. This lesion was most likely secondary to distant periorbital radiotherapy, which the patient sustained during treatment for retinoblastoma during childhood.