IMMUNOHISTOCHEMICAL AND IN-SITU HYBRIDIZATION DETECTION OF GROWTH-HORMONE-PRODUCING CELLS IN HUMAN THYMOMA

We have studied 25 thymomas by both immunohistochemistry and in situ h ybridization for the presence of growth hormone (GH)-producing cells O ur results indicate that 1) GH-immunoreactive cells were present in 13 of 17 thymomas of cortical and predominantly cortical type but not in medullary (spindled) thymomas (n = 3) or low- to high-grade thymic ca rcinomas (n = 5), 2) GN-positive cells we-re mainly located at the per iphery of the neoplastic lobules, at the periphery of the perivascular spaces and in the areas of medullary differentiation, 3) cells contai ning GH mRNA appeared at locations similar to those of GH-immunoreacti ve cells, and 4) GH-immunoreactive material was present only in the ep ithelial cell component as revealed by immunoelectron microscopy. In c onclusion, this paper demonstrates the occurrence of GN-producing cell s in noncarcinoid thymic tumors, The relevance of Gn in thymoma cell b iology requires additional investigations.