Giant invasive pituitary adenoma extending into the sphenoid sinus and nasopharynx: report of a case with intraoperative cytologic diagnosis.
BACKGROUND: Invasive pituitary adenomas involving the skull base are difficult to distinguish from other, more aggressive tumors. Intraoperaive diagnoses are crucial for deciding the course of treatment. CASE: A large mass extending from the sella turcica to the sphenoid sinus and nasopharynx was identified in a 42-year-old male. Because of the lack of endocrine abnormalities and lack of an apparent rise in pituitary hormones, preoperative diagnoses included chordoma, chondrosarcoma, meningioma and pituitary adenoma. Tumor fragments were easily squeezed into a thin layer of cells for cytologic specimens. Uniform, round tumor cells were arranged in minimally cohesive cell sheets and possessed regular, ovoid nuclei with a fine chromatin pattern and granular cytoplasm with prominent Golgi areas. The cytologic features indicated a probable diagnosis of pituitary adenoma and excluded other possibilities. Immunohistochemical demonstration of prolactin and ultrastructural features established the final diagnosis of prolactinoma. With the administration of bromocriptine, a large reduction in tumor size occurred. As compared to frozen sections, cytologic preparations are more effective for the intraoperative diagnosis of pituitary adenomas. Such neoplasms should always be included in the differential diagnosis of tumors involving the skull base.