A Case Report of FSH-Producing Nasal Ectopic Pituitary Adenoma Extending to the Frontal Cranial Fossa

We report the first case of an ectopic pituitary adenoma in the nasal cavity that produced follicle-stimulating hormone (FSH). A 60-year-old man complaining of left nasal bleeding had a polypoid tumor in the left nasal cavity. Findings of computed tomographic scanning and magnetic resonance imaging showed that the tumor originated from the olfactory cleft, occupied the nasal cavity, and extended to the frontal cranial fossa. Results of histologic examination suggested ectopic pituitary adenoma. Magnetic resonance imaging results showed the pituitary gland to be normal. Electron microscopy findings demonstrated a large number of secretory granules in the tumor cells that were positive for FSH on immunohistochemical analyses. Serum gonadotropin levels were normal, and no clinical signs of hypersecretory syndrome were noted. The above findings led us to establish the diagnosis of FSH-producing ectopic pituitary adenoma. The patient underwent craniofacial resection of the tumor followed by an uneventful recovery. The pathologic findings and clinical course of the case were comparable to those of FSH-producing adenomas arising from the pituitary gland.