Granular cell tumor of the neurohypophysis: report of a case with intraoperative cytologic diagnosis.

Cytological techniques including touch and smear preparations are very useful diagnostic modality in the evaluation of central nervous system (CNS) lesions and, in many instances, may be effectively used as the sole modality of tissue preparation for intraoperative consultation. Cytologic preparations offer many advantages over frozen sections for CNS specimens. These include selective examination of multiple areas from small biopsy specimens, superior preservation and details of cellular morphology, fewer artifacts, faster results, and improved cost-effectiveness. We describe the cytologic diagnosis of a granular cell tumor (GCT) of the neurohypophysis in a 33-year-old male who presented with headache and blurred vision. CT scan revealed an enlarged sella with a 2.15 x 2.0 cm pituitary lesion. Transsphenoidal resection of the mass was performed and submitted for intraoperative consultation. Smears and touch preparations were made on a portion of the mass that showed uniform polygonal cells with round to ovoid nuclei and abundant eosinophilic granular cytoplasm. An intraoperative cytological diagnosis of "favor GCT" was rendered. The histologic sections of the remaining material confirmed the diagnosis. Although GCT of the neurohypophysis is very rare, a specific intraoperative cytological diagnosis is possible. We report the clinical, cytological, and pathological findings of a GCT affecting the neurohypophysis.