The mass was biopsied.

Microscopic description: Histology sections show lobules and nests of uniformed neoplastic epithelial cells in a richly vascularized stroma. The tumoral cells are round to polyhedral with uniformed round nuclei and granular eosinophilic cytoplasm. Less than one mitosis per 10 HPF is seen. Some of the cells show degenerative changes.

Diagnosis: Pituitary adenoma.