Light microscopical morphometry, immunocytochemistry, and clinical correlations of pituitary adenomas at various...

In a series of 124 pituitary adenomas displaying oncocytic alterations, we studied the degree of oncocytic transformation by light microcopical and morphometrical means for semiquantitative analysis. We established three groups with different percentages of oncocytically transformed cells for comparison of clinical and immunocytochemical data. Of the patients, 32.3% exposed adenomas with less than 50% oncocytic alterations (group I), whereas 22.6% showed tumours with oncocytic transformations between 51% and 75% (group II). Oncocytic parts consisting of more than 75% of the tumour cells were found in 41.1% of the patients (group III). All three groups differed in the rate of immunocytochemically positive cases, but not in sex distribution, tumour size, and rate of recurrency. Immunocytochemical analyses for PRL and GH (81 vs 78 adenomas) showed a decline of immunohistochemically positive adenomas with increasing proportions of oncocytic transformation for both hormones. Whereas in group I 38% of the adenomas were PRL-positive and 15% GH-positive, group III displayed only 9% PRL-positive and 3% GH-positive adenomas. The results display the correlation between the increasing volume of oncocytic transformation and its effect on decreasing hormone content in pituitary adenomas.