Pituitary metastases are uncommon, with breast and lung carcinomas being the most common primary sites. Of the minority that are symptomatic, diabetes insipidus (DI) is frequently present. We report two cases, one presenting with DI and the other with hypopituitarism and DI, who deteriorated rapidly and died within 3 months.
Case 1: A previously fit 53-year-old lady presented in December 2008 with a one month history of polyuria and polydipsia. Investigations confirmed DI. Baseline anterior pituitary function was normal. An MRI showed increased bulk and marked enhancement of the hypothalamus, pituitary gland and infundibulum with multiple enhancing lesions throughout the brain. She was noted to have a breast lump and mammography revealed moderately dense glandular tissue with a prominent duct pattern. CT confirmed a right-sided breast mass with right axillary, supraclavicular and mediastinal lymphadenopathy. Widespread sclerotic bone metastases were present. She died in March 2009.
Case 2: A 47-year-old lady was diagnosed with bilateral breast carcinoma with bone and liver metastases in 2007. She underwent bilateral mastectomies and received chemotherapy and radiotherapy in 2008. She presented in May 2009 with symptoms suggestive of hypopituitarism confirmed on biochemical testing. She also had DI. She was commenced on hydrocortisone, thyroxine and DDAVP. MRI demonstrated a large pituitary lesion with significant suprasellar extension. She underwent endoscopic transsphenoidal biopsy and histology was consistent with metastatic breast carcinoma. She received pituitary radiotherapy but died in August 2009.
Discussion: Published series of pituitary metastases have reported mean survival rates of 622 months. Both our patients had established metastatic disease elsewhere but once they presented with clinical features of pituitary involvement they deteriorated rapidly and died within 3 months. These cases also highlight that presentation with DI, unusual with pituitary adenomas, should alert the clinician to the probability of more sinister underlying hypothalamic-pituitary pathology.