Light and electron microscopical morphometry of pituitary adenomas in hyperprolactinemia

Two highly differentiated acidophil prolactin-cell adenomas with hyperprolactinemia (group I), 8 large cell chromophobe adenomas with hyperprolactinemia (group II), and 2 small cell chromophobe adenomas (group III), one of which was combined with hyperprolactinemia, were studied immunohistologically. Morphometry was performed on the light- and electron microscopical level. The 11 active adenomas were immunohistologically positive for prolactin, the 12th adenoma with normal prolactin plasma level was negative for prolactin. Light microscopical morphometry displayed significantly more cells of smaller size in the "small cell chromophobe" adenomas, whereas the large cell chromophobe adenomas and the highly differentiated prolactin cell adenomas were not different. Ultrastructural morphometry demonstrated significant differences between highly differentiated prolactin cell adenomas (group I), and large cell chromophobe adenomas (group II). The latter contain smaller "relative volumes" of nucleoli and of secretory granules, whereas the rough endoplasmic reticulum, the Golgi fields and the nuclei were not different. Comparison of large cell chromophobe adenomas (group II), and small cell chromophobe adenomas (group III) revealed significantly larger relative volumes of nuclei and of mitochondria but smaller volumes of rough endoplasmic reticulum and of Golgi fields in the small cell chromophobe adenomas. Significant differences between the active and the inactive adenoma of small cell chromophobe type in the group III were not found. In spite of the low quantity of small cell chromophobe adenomas and of acidophil prolactin cell adenomas, our data demonstrate that there exist distinct and significant light microscopical and ultrastructural differences between the three adenoma types.(ABSTRACT TRUNCATED AT 250 WORDS)