Diabetes insipidus and panhypopituitarism due to intrasellar metastasis from medullary thyroid cancer.

Background: Medullary thyroid cancer (MTC) commonly metastasizes to lymph nodes in the central and lateral neck, but spread to distant organs also occurs, typically involving lung, liver, and bone. Metastases to pituitary gland are rare for this tumor.
Methods: We describe an unusual case and peculiar presentation of pituitary metastasis from MTC. We report clinical, genetic, and laboratory data of this patient.
Results: A young woman with multiple endocrine neoplasia type 2B was seen with recent onset of classic symptoms and signs of panhypopituitarism, mild diabetes insipidus, and optic chiasmatic compression. Transphenoidal resection of an intrapituitary mass confirmed the presence of metastatic MTC.
Conclusions: MTC recurrence may present solely with subacute pituitary symptomatology, even in the context of a very lengthy interval after initial surgery, atypically low calcitonin plasma levels, carcinoembryonic antigen doubling times, and the concomitant absence of other tell-tale signs of disseminated metastatic disease.