[Apparent contradictory findings in the immunohistochemical detection of hormone production in hypophyseal adenoma].

In some cases of pituitary adenomas, the immunohistochemical proof of a hormone production does not correspond with the clinical findings. False negative results are caused by different functional stages of the adenoma cells when hormone granules are largely released. Then, the intracellular content of hormone granules lies under the immunohistochemical demonstrability although clinical findings show high serum values of the hormone in question. Especially in prolactinomas, sparsely granulated forms are not rare. In these cases, the proof of a hormone production is possible by means of immuno-electronmicroscopy. Preoperative application of a bromocriptine therapy may falsify the results too. False positive results may occur in "plurihormonal" adenomas. True plurihormonal adenomas--especially the combinations GH/PRL and FSH/LH--exist but frequently reported combinations of several hormones should be seen with care. Often, the operatively removed tissue is cut into small pieces not only containing adenomatous tissue but also parts of the neighbouring normal pituitary gland with a production of several or even all hormones investigated. By use of GFAP or S-100 protein for the detection of folliculostellate cells, adenomatous and normal pituitary tissue can be differed. Folliculostellate cells can only be found in normal pituitary but not in adenomas.