A very rare case of pituitary metastasis infiltrating a non-secretory gonadotroph adenoma

Pituitary adenomas are the commonest sellar tumours. Pituitary metastases are very rare, with the most common primaries being breast and lung cancers. We report the case of an 83-year-old man with a history of breast carcinoma who presented with recent-onset headaches and progressive deterioration of visual acuity. MRI brain showed a large sellar and suprasellar mass compressing the optic chiasm and involving the pituitary stalk. Transsphenoidal debulking resulted in symptomatic relief and visual recovery. Specimen examination revealed a combination of a gonadotroph pituitary adenoma that was infiltrated by metastatic breast carcinoma. He had no symptoms of diabetes insipidus. He was subsequently treated with pituitary radiotherapy. This is a very rare presentation of a pituitary mass with mixed pathology. To our knowledge, this is the third description of a breast carcinoma metastasis into a gonadotroph cell pituitary adenoma.