Histology
The sections show a moderately cellular pituitary adenoma comprising trabeculae and nests, surrounded by vascularised stroma. The tumour cells have mildly enlarged round nuclei, finely granular chromatin and moderate amounts of eosinophilic cytoplasm. There are no atypical features. No normal anterior pituitary gland tissue is present. In specimen 2, there is respiratory type sinus mucosa and a small amount of minor salivary gland tissue. The tumour cells are positive for FSH, SF-1 and very focally with LH. Immunostains for prolactin, TSH, ACTH and GH are negative. The Ki-67 index is less than 1%.
FINAL DIAGNOSIS: Pituitary tumour: Gonadotroph cell adenoma.