MON-285 Clinical Characteristics of Six Patients with Infundibulo-Neurohypophysitis

Background: To date, precise pathological studies and the improvement of imaging studies have made it clear that a part of idiopathic diabetes insipidus (DI) could be lymphocytic infundibulo-neurohypophysitis (LINH) caused by autoimmune abnormality. Recently, anti-rabphilin (RPH) 3A antibody was identified and expecting as a useful diagnostic marker of LINH*. Objective: Here, we present the clinical course of 6 patients with central DI (CDI) who were thought to be due to LINH and compared with results of serum anti- RPH3A antibody in each. Patients and methods: Clinical characteristics of 6 patients with CDI regarded as due to LINH (M/F; 3/3, age range; 26–67 years old) were investigated. Clinical course, anterior pituitary functions, MRI findings, complications and results of serum anti-RPH3A antibody were retrospectively analyzed by medical charts. Pituitary biopsy was conducted in 2 patients. Results: On the T1-weighted MR image, one patient (# 3: 67 F) had only a lacking of high signal intensity in the posterior lobe. Thickening of pituitary stalk was seen in other 5 patients. Anti-RPH3A antibody was studied in those 5 patients and positive in 3 and negative in 2. Anterior pituitary function was preserved in 2 patients with positive anti-RPH3A antibody. One patient (#1: 26 F) was diagnosed as LINH by changes in MRI findings over time and the other patient (#5: 41 M) by pituitary biopsy. Impaired anterior pituitary function was observed in 2 of 6 patients. One patient (# 2: 32 F) suffered from CDI since late pregnancy. She had a history of massive bleeding at delivery. Postpartum evaluation revealed that besides CDI, she had TSH, ACTH and GH deficiency. Anti-RPH3A antibody was positive in this patient. A mild low GH response (not severe GHD) to GHRP-2 test was seen in another patient (#4: 37 M). Pituitary biopsy of this patient revealed that infiltration of lymphocytes distributed not only posterior but also anterior pituitary. Anti-RPH3A antibody was negative in this patient. As a complication, Type 2 DM in 2 patients, Graves’ disease and cerebral infarction in one each were observed. Conclusion: Anti-RPH3A antibody was useful as a non-invasive diagnostic marker for LINH. However, among patients who were inferred to have LINH, the clinical course, a degree of extension and severity of inflammation in the pituitary region varied from case to case, suggesting that the clinical features of LINH might be diverse. *: JCEM 100: E 946, 2015