Abstract #1411935: A Radiographic Diagnosis: IgG4-Related Hypophysitis Presenting with Hypopituitarism and Central Diabetes Insipidus

Abstract

Hypophysitis is defined as inflammation of the pituitary gland. IgG4-related hypophysitis is a rare form and isolated IgG4-related hypophysitis is even more rare. Here, we discuss an interesting patient who presented with symptoms of diabetes insipidus and was found to have panhypopituitarism with suspicious MRI findings of a suprasellar mass and a thickened pituitary stalk, suggestive of IgG4-related hypophysitis. A 69-year-old male with past medical history of lung adenocarcinoma status-post right pneumonectomy, chronic obstructive pulmonary disease, orthostatic hypotension, and poor oral intake due to esophageal compression presented with acute encephalopathy and sepsis secondary to pneumonia. CT head scan done for encephalopathy showed a 1.2 cm suprasellar mass. On consultation, the patient was found to be hypernatremic. Upon further questioning, the patient reported experiencing polydipsia, nocturia, chronic cold intolerance, fatigue, and impotence for several weeks to months. He denied any vision changes, breast tenderness, or galactorrhea. Laboratory testing revealed a sodium level of 157 mmol/L (n.135-145 mmol/L) with plasma osmolality elevated at 332 mOsm/kg (n.275-295 mosm/kg). Urine sodium was low at < 20 mmol/L. Desmopressin (DDAVP) 0.1mg nightly was started given concern for diabetes insipidus. Peak cortisol after performed Cosyntropin stimulation test resulted at 13.5mcg/dL with an ACTH 6 pg/mL (n.6-50 pg/mL). TSH was < 0.01 mU/L, free T4 1.79 ng/dL, and free T3 4.9 nmol/L. The elevated free T3 was felt to be from heparin displacement. Total testosterone was 84 ng/dL with suppressed FSH and LH. Elevated prolactin of 39 ng/mL was thought to be from stalk-effect. MRI of the pituitary gland revealed a 1.3cm enhancing suprasellar mass in the region of the optic chiasm and a smaller 9mm intra-sellar mass, with a thickened pituitary stalk. Given these radiologic findings and the patient's age and gender, the possibility of IgG4 hypophysitis was suspected. CT chest, abdomen, and pelvis were unremarkable. In addition to the DDAVP, he was started on high-dose hydrocortisone, thyroxine replacement, and testosterone replacement. Serum IgG4 level was 23.6 mg/dL (n. 4-86 mg/dL). A six week repeat pituitary MRI is pending; however, the patient is clinically improving and doing well. Specific radiologic findings, such as thickened pituitary stalk and pituitary enlargement with suprasellar mass, led us to strongly consider IgG4-related hypophysitis in our differential for this patient. Clinical presentation of panhypopituitarism, along with patient age and gender, also supported the diagnosis of IgG4-related hypophysitis. Although this patient does not meet all Leporati diagnostic criteria for IgG4-related hypophysitis, the high degree of suspicion led to prompt treatment with high dose steroids. High dose steroids have been shown to revert symptoms and prevent irreversible fibrosis. This case highlights the need for radiologists and endocrinologists to work together in the early recognition of the diagnosis and treatment of IgG4-related hypophysitis.