MICROSCOPIC DESCRIPTION:
The sections show a moderately cellular pituitary adenoma comprising trabeculae and nests, surrounded by vascularised stroma. The tumour cells have mildly enlarged round nuclei, conspicuous nucleoli and moderate amounts of granular eosinophilic cytoplasm. There are no atypical features. No normal anterior pituitary gland tissue is present. The tumour cells are diffusely and weakly positive for growth hormone. CAM5.2 shows only very occasional fibrous bodies (not shown). The Ki-67 index is about 1% (not shown). Immunostains for the other pituitary hormones are negative (not shown).
DIAGNOSIS: Pituitary tumour: Growth hormone secreting pituitary adenoma.