PITUITARY ADENOMAS WITH ACROMEGALY LIGHT MICROSCOPIC AND ELECTRON MICROSCOPIC STUDY OF 60 CASES

Analysis of 60 pituitary adenomas with acro- megaly iiS made. All 60 surgical specimens are studied by both light and electron microscopy. By light microscopy we classified the adenomas into strong acidophilic cell (16 cases) and weak acidophilic cell (20 cases), stem cell (2 cases) and mixed cell type adenomas (22 cases). By electron micros.copy we classified them into densely granulated (14 cases) and sparsely granu- lated growth hormone (GH) cell adenomas (212 cases) in which there are fibrous bodies near the indented part of the nucleus which are of diagnostic value, corresponding to the round lucent area near the indented nucleus seen by light microscopy. The densely granulated and sparsely granulated GH cells may coexist within 1 adenoma (4 cases). Some adenomas may con- tain 2-3 kinds of secretory granules and are called multiple functional adenomas, in this series 18 had GH-;-PRL prolactin), 1 GH+ACTH and l GH+PRL+ACTH. Strong acidophilic cells correspond to densely granulated GH cells while weak acidophilic celIs correspond to sparsely granulated GH cells. The number of strong or weak acidophilic cells and number of secretory granules are not directly proportional to the GH blood level. By electron microscopy GH, PRL and ACTH secretory granules have characteristic features which are not absolute. Correct diagnosis is based upon combining the clinical symptoms and signs, blood hormone levels and secretory granule morphology. F'ibrous body diagnostic value and their genesis and development are dis- cussed.