Intraoperative cytologic diagnosis of suprasellar and sellar cystic lesions.

The intraoperative distinction of craniopharyngiomas (CP) and cystic pituitary adenomas (PA) from other intracranial parasellar cystic lesions can significantly modify the extent of surgery and reduce postoperative morbidity. Frozen-section diagnosis may be limited by the scant tissue available for examination. The imprint cytology of six parasellar cystic lesions is examined, along with their radiologic and histologic findings. These include two Rathke's cleft cysts (RCC), three CP, and one cystic PA. RCC showed scattered clusters of cuboidal cells with prominent cilia. Cystic PA demonstrated clusters of monomorphic round cells with minimal cytoplasm. CP displayed "wet" keratin and clusters of squamous cells with a palisaded border. In all six cases, cytology supported the final histologic diagnosis. In one case, the intraoperative diagnosis was based solely on cytologic examination. Cytology can contribute significantly to an accurate intraoperative diagnosis of parasellar cystic lesions and potentially modify surgical management.