[Ectopic pituitary adenoma. Case report and review of literature].

Ectopic pituitary adenomas are very rare neoplasms. They are usually located in the sphenoid sinus or nasopharynx. Ectopic tumors derive from a residual pituitary fragment in the craniopharyngeal duct. They are similar in morphology, immunohistochemistry and hormonal activity to the typical pituitary adenoma. One third ectopic pituitary tumors reported in the literature are endocrine inactive, while the remaining ones indicate a hormonal activity and usually secrete ACTH, causing the Cushing disease. About 50% of pituitary adenomas are located at the skull base and present as aggressive neoplasms. The computed axial tomography (CAT) and magnetic resonance imaging (MRI) are very useful in revealing the presence of these tumors. Preoperative diagnosis of ectopic pituitary adenomas located at the skull base is difficult. Diagnostic procedures usually suggest another type of neoplasm, e.g. chordoma, nasopharyngeal carcinoma, or a metastatic tumor. Pathological examination including immunohistochemical studies of neuroendocrine markers is important in establishing the diagnosis. A unique case of ectopic, nonfunctioning pituitary adenoma involving the sphenoid sinus and nasopharynx and causing palsy of cranial nerves is presented. MRI examination revealed the presence of a large invasive tumor. The neoplasm was partially resected by transnasal approach. The diagnosis was confirmed by a pathological examination including immunohistochemical smears.