A 47‐year‐old man with a history of stroke presented after a fall without loss of consciousness. He reported increased thirst and urination as well as headaches without vision changes. Vital signs including orthostatics were normal, and physical exam was unremarkable. Visual fields were intact and there was no thyromegaly or skin abnormalities. Laboratory studies revealed hypernatremia with the remainder of the chemistry panel normal. CT of the head showed no acute abnormalities but revealed a 10‐mm suprasellar mass not seen on prior imaging. The patient complained of extreme thirst and consumed up to 15L of fluid daily. Urine osmolality was 69 mOsm/kg. Prolactin was borderline elevated and testosterone was low. TSH, GH, IGF‐1, cortisol, FSH, LH, and ACTH were normal. MRI of the brain showed an enlarged pituitary gland with thick infundibulum and features of lymphocytic hypophysitis. He received intranasal desmopressin and urine output decreased. Urine osmolality and serum sodium normalized. He was diagnosed with central diabetes insipidus due to lymphocytic hypophysitis and hypopituitarism. Thereafter, he received desmopressin and testosterone replacement with periodic laboratory monitoring.
Sellar masses are typically caused by pituitary adenomas and less frequently by other malignant/benign tumors or physiologic enlargement of the pituitary gland. Symptoms/findings include headache, vision changes, hormonal abnormalities, or incidental imaging findings. Lymphocytic hypophysitis is a rare cause of sellar masses and hypopituitarism. It is an autoimmune disorder characterized by a lymphocytic pituitary infiltrate causing enlargement of the gland and destruction of pituitary cells. It is most often seen in peripartum women. Over 1/2 patients have secondary hypoadrenalism. Diabetes insipidus occurs in 1/3 of patients. Concurrent autoimmune diseases such as thyroiditis or systemic lupus erythematosus are common. MRI is the standard imaging modality, revealing a pituitary mass often indistinguishable from an adenoma. In contrast to pituitary tumors, hypophysitis is typically symmetrical and homogeneous with thickened but nondisplaced stalk. In addition, prolactinomas typically are associated with prolactin levels > 200 ng/dL Biopsy is the gold standard for diagnosis but is not required for initiating treatment in the proper clinical context. In this patient, diabetes insipidus along with convincing imaging led the team to forgo biopsy. Without visual field disturbances, surgical therapy is withheld. Inflammation often resolves spontaneously. Because hypophysitis is rare, no definitive guidelines for treatment exist. Patients should receive hormonal replacement therapy and serial monitoring for development of other endocrine abnormalities.
Lymphocytic hypophysitis is rare but should be considered in the differential diagnosis of pituitary masses and hypopituitarism, particularly in peripartum women and those with other autoimmune diseases.
To cite this abstract:Kay J, Smith D, Jones D. Diabetes Insipidus As the Presenting Manifestation of a Rare Pituitary Disorder. Abstract published at Hospital Medicine 2013, May 16-19, National Harbor, Md. Abstract 451. Journal of Hospital Medicine. 2013; 8 (suppl 2). https://www.shmabstracts.com/abstract/diabetes-insipidus-as-the-presenting-manifestation-of-a-rare-pituitary-disorder/. Accessed May 22, 2019.