Lymphocytic infundibuloneurohypophysitis with positive anti-rabphilin-3A antibodies nine years post-onset of central diabetes insipidus

Childhood-onset lymphocytic infundibuloneurohypophysitis (LINH) due to infiltration of autoimmune lymphocyte in the neurohypophysis is rarely reported. Its definitive diagnosis requires a pituitary biopsy, which is an invasive procedure. Recently, anti-rabphilin-3A antibody has been reported as a potential diagnostic marker for LINH in adults; however, only a few cases have been reported in children. Here, we present a case of childhood-onset LINH in a 10-yr-old boy identified as anti-rabphilin-3A antibody positive during chronic phase, 9yr post-onset of central diabetes insipidus (CDI). T1-weighted magnetic resonance imaging (MRI) revealed pituitary stalk thickening and absence of posterior pituitary bright signal spot, and the hormonal responses of the adenohypophysis to GHRH, TRH, CRH and LHRH revealed no abnormalities during the first admission. MRI at 5 mo post-onset indicated reduced stalk swelling: however, replacement treatment with intranasal desmopressin was continued to counter unimproved CDI. Additionally. OH replacement therapy was also initiated to counter its deficiency. Pituitary re-enlargement was not observed in the subsequent routine MRI, and no increase was observed in the levels of tumor markers during follow-up, which was considered clinically consistent with LINH. Our case study suggests that anti-rabphilin-3A antibody may be considered as a useful diagnostic marker for LINH in children.

Automated summary

Childhood-onset lymphocytic infundibuloneurohypophysitis (LINH) is rare, and definitive diagnosis requires pituitary biopsy. This case of a 10-year-old boy with LINH suggests that anti-rabphilin-3A antibody may be a useful diagnostic marker in children. Treatment includes desmopressin replacement and other hormone replacement therapies.