Endocrine Abstracts

Introduction: Central diabetes insipidus (DI) is a frequent complication of transfenoidal surgery for Cushing’s disease (CD). It can be transient or, more infrequently, permanent. The most common mechanism results from surgical neurohypophyseal damage rather than local mass effect from the pituitary adenoma.

Case report: A 40 years old woman was referred to our Endocrinology outpatient clinic at the beginning of 2015 for new onset hypertension, significant weight gain, mood disturbance, proximal muscular weakness and amenorrhea. After a year of follow-up, she was formally diagnosed with cyclic CD, hypogonadotrophic hypogonadism, central hypothyroidism, as well as a pituitary macroadenoma (12×16×15 mm) with pituitary stalk enlargement. She had surgery in March 2016, with no post-operative complications. Histology confirmed an ACTH positive adenoma. Her initial symptoms resolved, except for central hypothyroidism. She required hydrocortisone treatment for 5 months, with no adrenal insufficiency afterwards. About two years after surgery, the patient started complaining of increased thirst and water intake (3 to 4.5 l of water/day) and 24-hour urinary output. She also noted weight gain again. Further evaluation confirmed hypercortisolism relapse and revealed a new onset partial DI. MRI showed an increased thickeness of the pituitary stalk (7×7×10 mm), more significant than before, associated with a residual lesion at this location. Other infiltrative disorders of the pituitary stalk were excluded. The patient was started on desmopressin and a new surgical procedure is under consideration.

Conclusion: This case illustrates a rare form of CD relapse, with associated DI, possibly related with the location of the residual lesion at the pituitary stalk. It should alert the clinicians to be aware for DI symptoms during follow-up, even a long time after surgery.