The patient went on to have transsphenoidal surgery.
Histology
Paraffin sections show a moderately cellular pituitary adenoma. It comprises sheets and nests, surrounded by vascularised stroma. The tumour cells have mildly enlarged round nuclei, finely granular chromatin and moderate amount of pale to amphophilic cytoplasm. No atypical features are identified. No normal anterior pituitary gland tissue is present. The tumour cells are prolactin positive and the pattern of staining corresponds to that of a sparsely granulated adenoma. The tumour cells are negative for all remaining pituitary hormone markers. The Ki67 proliferative index is 1%. The features are of a sparsely granulated prolactin secreting adenoma.
FINAL DIAGNOSIS: Pituitary adenoma: Sparsely granulated prolactin secreting adenoma.