Midline Nut Carcinoma

38-year-old female with a history of left-sided proptosis and orbital pain. There is an infiltrative, T2-isointense mass which restricts diffusion and demonstrates heterogeneous enhancement. The lesion is located within the ethmoid air cell complex eroding through both the lamina papyracea, osseous nasal septum, orbital roof and floor of the anterior cranial fossa. The lesion abuts and is indistinct from the overlying dural surface. The lesion also encases and invades the proximal muscle bellies of the superior and medial rectus muscles. The differential diagnosis includes primary sinus carcinoma, such as squamous cell or undifferentiated carcinoma. Though slightly posterior in location, the lesion did extend to involve the cribiform plate, so esthesioneuroblastoma was also given. On surgical resection, this was found to be a midline Nut carcinoma. Midline Nut carcinoma carcinomas are characterized by chromosomal rearrangements that involve the gene encoding the nuclear protein of the testis, or NUT for short. The tumor primarily affects children and young adults. Many patients have metastatic disease at time of presentation.