Latta, Eleanor

Ghrelin, an orexigenic hormone occurs mainly in stomach, and in several tumor types. We investigated ghrelin immunopositivity using the streptavidin‐biotin‐peroxidase complex method in the full spectrum of pituitary adenoma subtypes. Quantification was undertaken by analyzing both the percentage of tumor cells stained for ghrelin and the staining intensity. Cytoplasmic ghrelin immunopositivity was identified in several adenoma subtypes. Not every cell was immunopositive; the intensity of staining differed among cells within the given lesion and among the various tumors. The highest scores were noted in GH adenomas exposed to somatostatin analogues. In decreasing order, lower scores were encountered in ACTH‐producing, silent subtype 1 and 2 adenomas in Cushing disease, silent subtype 3 adenomas, untreated GH adenomas, dopamine agonist‐treated PRL adenomas, gonadotroph adenomas, and ACTH adenomas in Nelson syndrome. No immunoreactivity was found in TSH, untreated PRL‐producing, and null cell adenomas. The high immunoexpression of ghrelin in GH adenomas exposed to somatostatin analogues, may be due to increased ghrelin synthesis or to suppression of its release.