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. HIGHLIGHT POINTS: Infiltrating metastases into pituitary adenomas are very rare but do occur. To our knowledge this is the third case of breast adenocarcinoma metastasising to a gonadotroph pituitary adenoma. Pituitary metastases should always be considered in rapidly evolving pituitary symptoms in a cancer patient. Not all complex pituitary lesions are associated with panhypopituitarism. Early invasive local management (TSS and post TSS radiotherapy) can provide rapid satisfactory outcomes.