A case of hypopituitarism secondary to metastatic colonic adenocarcinoma.

Introduction: Cancers that metastasise to the pituitary gland are unusual. The clinical manifestations of these can be varied making the diagnosis challenging. The most common cancers that metastasise to the pituitary are breast and lung which together account for more than two-thirds of cases. There have been reports of other types of cancers metastasising to the pituitary but these are rare. Case An 86 year old female with a previous history of a laparotomy for Duke’s C Adenocarcinoma was admitted with symptoms of spontaneous hypoglycaemia and postural hypotension. Her urine output was normal. Investigations included an ACTH stimulation test with a basal cortisol measurement of 98 nmol/l and subsequent readings of 236 nmol/l (30 minutes) and 316 nmol/l (60 minutes) after receiving 250 µg of tetracosactide. Her concurrent basal ACTH measurement was <5 ng/L. Her TSH was 0.30 mIU/L (0.3–5.0 mIU/L), fT4 of <4 pmol/L (11–23 pmol/L), LH of <0.1 IU/L (>25 IU/L), FSH of 1.0 IU/L (>30 IU/L) , IGF-1 of <3.3 nmol/l and a prolactin of 74 mIU/L (60–620 mIU/L). A CT scan of her abdomen revealed bulky adrenal glands with reduced enhancement of the central portions. MRI of the pituitary gland showed an enlarged gland with suprasellar extension and the radiological impression was that of a pituitary microadenoma. The patient was started on hydrocortisone and thyroxine therapy with a clinical improvement and resolution of the hypoglycaemic episodes. She was discharged to a rehabilitation centre with planned follow up including an adrenal MRI scan. She was however re-admitted with an adrenal crisis and severe hypoglycaemia - she did not survive this episode. Post mortem examination revealed evidence of metastatic lesions to the liver, adrenals, pituitary gland and pancreas. The histological samples from these lesions showed findings consistent with metastatic colonic adenocarcinoma to the pituitary.