@entity977 as an unsuspected XXXX .

@entity1 @entity1313 @entity5 @entity3580 @entity977 @entity652
@entity977 are common @entity5 that account for about 10% of @entity1313 . Most arise from the adenohypophysis and are confined to the region of the sella turcica. Other sites may be involved as a result of extension, infiltration, or ectopic location. However, posterior extension or ectopic involvement of the clivus of the sphenoid and occipital bones is rare. Seven @entity1 with destructive clival masses were referred to our institution with presumptive diagnoses of @entity3580 . In all cases, histologic workup revealed @entity977 . Because they represent a subset of @entity652 , the histologic features of the @entity5 were studied, and the clinical histories of the @entity1 were reviewed. Five of the @entity1 were @entity1 , aged 31 to 67 years, and two were @entity1 , aged 55 and 67 years. Four @entity1 had extremely high plasma concentrations of prolactin (8,132-22,424 ng/ml, nl < 15). @entity5 resembled @entity652 ; however, three exhibited nuclear pleomorphism, mitotic figures, and other morphologic features, suggesting alternate diagnoses. Three required immunoperoxidase stains in addition to those for pituitary hormones, and three required electron microscopy for diagnosis. Destructive invasion of the clivus by @entity977 is rare, and anaplastic features of some of the @entity5 may lead to difficult diagnoses.
