Silent pituitary adenomas. An ultrastructural study.

Thirty cases of silent pituitary adenomas were studied clinico-morphologically and classified into 4 groups according to their fine structural characteristics. Tumors poor in organelles (7 cases) and typical oncocytomas (6 cases) produced pituitary insufficiency significantly more frequently than did tumors with moderately oncocytic changes (10 cases) and non-oncocytic, organelle-rich adenomas (7 cases). The latter 2 groups were more prone to proliferate suprasellarly. Postoperative, short-term follow-up studies showed that intrasellar disease was common in all groups, whereas suprasellar disease was more frequent among the latter 2 than in the former 2 types of adenomas. Hence, it seems possible from the fine structure to deduce a subgrouping of clinical significance.