Endocrine Abstracts

Case: We present an interesting case of pituitary hypophysitis following ipilimumab therapy. A 66 year old lady previously diagnosed with left ocular melanoma in 2006 was under oncology follow up, when routine surveillance scan showed recurrence in segment six of the liver. She underwent laparoscopy and was found to have multiple liver metastases following which she was commenced on ipilimumab. Four weeks after completing her second cycle of ipilimumab, she developed severe headaches. MRI showed diffuse hypophysitis of the pituitary stalk and enhancement. She was found to have a random cortisol of 64 nmol/L and a low TSH of 0.05 miu/L with a FT4 of 7.7 pmol/L. Her FSH and LH were also low at 3.3 and 0.8 iu/L respectively. She did not have any visual field defect on formal testing of the right eye. She was started on dexamethasone 8 mg bd and soon after her headaches improved. At 6 weeks, her TSH, FSH and LH were all improved. She did not report any symptoms suggestive of diabetes insipidus. Follow up MRI at 3 months showed considerable improvement in pituitary and infundibular size. She was not recommenced on ipilimumab.

Insulin stress test at six months confirmed persisting hypocortisolism with a peak cortisol of 307 nmol/L only. Several months later, she developed progressive metastatic disease and passed away.

Discussion: Pituitary hypophysitis due to monoclonal antibodies, although rare has been reported before. In some cases the acute hypophysitis may resolve over a period of time with return of pituitary function to normal. In others, hypopituitarism persists as was the case in our patient. With the increasing use of biological therapy in management of advanced cancers clinicians need to be aware of this serious complication.