A pediatric case of central diabetes insipidus and hypopituitarism after COVID-19 suspected with lymphocytic hypophysitis with positive anti-rabphilin-3A antibodies - Case Report

Sep 30, 2026

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Lymphocytic hypophysitis (LYH) is a rare autoimmune disorder marked by lymphocytic infiltration of the pituitary, causing central diabetes insipidus (CDI) and hypopituitarism. Distinguishing LYH from other pituitary-enlargement conditions can be difficult, but anti-rabphilin-3A antibody (RPH3A-Ab) has been reported as a diagnostic aid. This report describes a 4-year-old girl who developed CDI one week after COVID-19 and anterior hypopituitarism 14 months later, with RPH3A-Ab positivity supporting LYH; MRI showed progressive pituitary stalk thickening that later improved. RPH3A-Ab may help suspect post-COVID-19 LYH even in children.

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Clinical Pediatric Endocrinology Vol.35 / No.1 January 2026 pp 98–103 Case Report A pediatric case of central diabetes insipidus and hypopituitarism after COVID-19 suspected with lymphocytic hypophysitis with positive anti-rabphilin-3A antibodies Taro Fukuta1 , Tatsuya Fukasawa2 , Haruki Mizutani1 , Shunsuke Kato1 , Takuya Ishikawa1 , Mai Fukushima1 , Naoko Iwata3, 4 , Haruki Fujisawa3 , Atsushi Suzuki3 , Yoshihisa Sugimura3 , and Takashi Hamajima1 1Department of Endocrinology and Metabolism, Aichi Children’s Health and Medical Center, Aichi, Japan 2Department of Pediatrics, Anjo Kosei Hospital, Aichi, Japan 3Department of Endocrinology, Diabetes and Metabolism, Fujita Health University School of Medicine, Aichi, Japan 4Department of Endocrinology and Diabetes, Daido Hospital, Aichi, Japan Highlights ● We report the first pediatric case of RPH3A-Ab-positive CDI after COVID-19 . ● This is also the first prepubertal case ofLYH following COVID-19 . ● RPH3A-Ab may be valuable in suspecting post-COVID-19 LYH even in children. Abstract. Lymphocytic hypophysitis (LYH) is a rare autoimmune disorder characterized by lymphocytic infiltration of the pituitary gland, leading to central diabetes insipidus (CDI) and hypopituitarism. Although distinguishing LYH from other diseases presenting with pituitary enlargement is challenging, the use of anti-rabphilin-3A antibody (RPH3A-Ab) in the diagnosis ofLYH has been recently reported. Case reports ofLYH following coronavirus disease 2019 (COVID-19) infection in adult and adolescent patients have been accumulated. Here, we present the first case confirming the presence of RPH3A-Abs in pediatric CDI following COVID-19 . A 4-yr-old girl developed CDI one week after COVID-19, and anterior hypopituitarism was confirmed 14 mo later. Head magnetic resonance imaging (MRI) revealed progressive pituitary stalk thickening, which subsequently improved. Although other disease-specific markers did not increase, serological testing confirmed the presence of RPH3A-Ab, supporting the clinical diagnosis of LYH. It has previously reported that RPH3A-Ab demonstrate high sensitivity and specificity in differential diagnosis ofLYH, and RPH3A-Ab are also identified as positive in pediatric cases ofLYH with a biopsy. Additionally, this is the first documented prepubertal case ofLYH following COVID-19 . Our case study indicates that LYH can occur in children after COVID-19, and RPH3A-Ab may be useful in its diagnosis. Key words: anti-rabphilin-3A antibody, lymphocytic hypophysitis, central diabetes insipidus, COVID-19 Received: April 10, 2025 Accepted: August 18, 2025 Advanced Epub: August 29, 2025 Corresponding author: Takashi Hamajima, M.D., Ph.D., Department of Endocrinology and Metabolism, Aichi Children’s Health and Medical Center, 7-426 Morioka-cho, Obu-city, Aichi 474-8710, Japan E-mail: [takashi_hamajima@sk00106.achmc.pref.aichi.jp](takashi_hamajima@sk00106.achmc.pref.aichi.jp) This is an open-access article distributed under the terms of the Creative Commons Attribution NonCommercial No Derivatives (by-nc-nd) License <[http://creativecommons.org/licenses/by-nc-nd/4.0/](http://creativecommons.org/licenses/by-nc-nd/4.0/)> . Copyright© 2026 by The Japanese Society for Pediatric Endocrinology Clin Pediatr Endocrinol 99 Introduction Lymphocytic hypophysitis (LYH) is a rare inflammatory disorder characterized by lymphocytic infiltrates invading the pituitary gland, and the underlying cause may be due to an autoimmune process (1, 2) . LYH is classified into three types: lymphocytic adenohypophysitis (LAH), lymphocytic infundibuloneurohypophysitis (LINH), and lymphocytic panhypophysitis (LPH) (2) . Depending on the typeof disease and case, LYH can cause central diabetes insipidus (CDI), hypopituitarism, and neurological symptoms, such as headache and visual field disturbances (2) . Differentiating LYH from other conditions presenting with a pituitary enlargement or pituita

FAQs

What condition does the case report focus on after suspected COVID-19?

The report focuses on a pediatric case of central diabetes insipidus and hypopituitarism associated with lymphocytic hypophysitis (LYH).

How was LYH supported in the 4-year-old patient?

The presence of anti-rabphilin-3A antibody (RPH3A-Ab) supported the clinical diagnosis of LYH when other disease-specific markers did not increase.

What did MRI show over time in this case?

Head MRI showed progressive pituitary stalk thickening, which subsequently improved.

Sep 30, 2026

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