[Folliculo-stellate cells in normal human adenohypophyses and in pituitary adenomas]

Nine normal human adenohypophyses and 155 cases of pituitary adenoma of various endocrinological types were studied for existence of folliculo-stellate cells (FSCs) by an immunohistochemical method using the antibody for S-100 (S-100 protein). In all normal materials, S-100 positive FSCs were distributed throughout the glands, constituting 0.9-4.0% of the adenohypophysial cells. FSCs were morphologically characteristic showing a few slender cytoplasmic processes which extended among the other endocrine cells. On the other hand, FSCs were recognized in 13 cases (8%) of the adenomas, which we called FSC-containing pituitary adenomas. In them, S-100 positive FSCs existed diffusely in the tissue and increased in number, but did not differ in appearance from those in the normal gland. We also examined immunoreactivity of FSCs for the anti-GFAP (glial fibrillary acidic protein) antibody. GFAP positive cells showed a greater number than S-100 positive cells in the normal glands, but a smaller number in the adenomas. Ultrastructural features of FSCs were observed in the tumor by an electron microscope. We studied clinical aspects of these FSC-containing adenomas, expecting some common features. However, we found no rules in age, sex, endocrinological type, tumor size, previous therapy, intraoperative finding of the tumor, and recurrence. So far, the function of FSC has not been clearly elucidated, and the present study did not contribute in this respect. The property of FSCs which proliferate in some adenomas is enigmatic. They may be entrapped normal cells, or reactive hyperplastic cells, or neoplastic cells. We considered them reactive hyperplastic cells.(ABSTRACT TRUNCATED AT 250 WORDS)