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Risk Factors for Pancreatic Stone Formation in Type 1 Autoimmune Pancreatitis

A Long-term Japanese Multicenter Analysis of 624 Patients

Ito, Tetsuya, MD, PhD*; Kawa, Shigeyuki, MD, PhD; Matsumoto, Akihiro, MD, PhD*; Kubota, Kensuke, MD, PhD; Kamisawa, Terumi, MD, PhD§; Okazaki, Kazuichi, MD, PhD; Hirano, Kenji, MD, PhD; Hirooka, Yoshiki, MD, PhD#; Uchida, Kazushige, MD, PhD; Masuda, Atsuhiro, MD, PhD**; Ohara, Hirotaka, MD, PhD††; Shimizu, Kyoko, MD, PhD‡‡; Arakura, Norikazu, MD, PhD§§; Masamune, Atsushi, MD, PhD∥∥; Kanno, Atsushi, MD, PhD∥∥; Sakagami, Junichi, MD, PhD¶¶; Itoi, Takao, MD, PhD##; Ito, Tetsuhide, MD, PhD***; Ueki, Toshiharu, MD, PhD†††; Nishino, Takayoshi, MD, PhD‡‡‡; Inui, Kazuo, MD, PhD§§§; Mizuno, Nobumasa, MD, PhD∥∥∥; Yoshida, Hitoshi, MD, PhD¶¶¶; Sugiyama, Masanori, MD, PhD###; Iwasaki, Eisuke, MD, PhD****; Irisawa, Atsushi, MD, PhD††††; Shimosegawa, Tooru, MD, PhD∥∥; Chiba, Tsutomu, MD, PhD‡‡‡‡

doi: 10.1097/MPA.0000000000001210
Original Articles

Objective Autoimmune pancreatitis (AIP) has the potential to transform into chronic pancreatitis with pancreatic stone involvement. This retrospective investigation sought to clarify the risk factors for stone formation in type 1 AIP.

Methods Questionnaires on patients with type 1 AIP were sent to 22 high-volume medical centers across Japan to compare the clinical features of patients with and without pancreatic stone formation.

Results Of the completed records on 624 type 1 AIP patients, 31 (5%) had experienced pancreatic stones. Median follow-up duration was 1853 days. Bentiromide test values at diagnosis were significantly lower, and hemoglobin A1c values after corticosteroid treatment were significantly higher in patients with pancreatic stones. Imaging results disclosed that pancreatic atrophy and hilar or intrahepatic bile duct stenosis were significantly more frequent in patients with pancreatic stone formation. Pancreatic head swelling tended to be more frequent in this group as well. On the other hand, a shorter follow-up period was associated with the nonformation of pancreatic stones.

Conclusions The increased frequency of pancreatic head swelling in type 1 AIP patients exhibiting pancreatic stones indicated a propensity for pancreatic juice stasis with subsequent stone development and pancreatic dysfunction occurring over longer periods of disease duration.

From the *Department of Gastroenterology, Shinshu University School of Medicine, Matsumoto;

Department of Internal Medicine, Matsumoto Dental University, Shiojiri;

Endoscopic Unit, Yokohama City University Hospital, Yokohama;

§Department of Internal Medicine, Tokyo Komagome Metropolitan Hospital, Komagome;

Department of Gastroenterology and Hepatology, Kansai Medical University, Hirakata;

Department of Gastroenterology, Tokyo Takanawa Hospital, Minato;

#Department of Endoscopy, Nagoya University Hospital, Nagoya;

**Department of Gastroenterology, Kobe University Graduate School of Medicine, Kobe;

††Department of Community-based Medical Education, Nagoya City University Graduate School of Medical Science, Nagoya;

‡‡Department of Gastroenterology, Tokyo Women's Medical University, Shinjuku;

§§Department of Gastroenterology, Aizawa Hospital, Matsumoto;

∥∥Division of Gastroenterology, Tohoku University Graduate School of Medicine, Sendai;

¶¶Department of Gastroenterology, Kyoto Prefectural University of Medicine, Kyoto;

##Department of Gastroenterology and Hepatology, Tokyo Medical University, Shinjuku;

***Department of Medicine & Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka;

†††Department of Gastroenterology, Fukuoka University Chikushi Hospital, Chikushino;

‡‡‡Department of Gastroenterology, Tokyo Women's Medical University, Yachiyo Medical Center, Yachiyo;

§§§Department of Gastroenterology, Second Teaching Hospital, Fujita Health University, Toyoake;

∥∥∥Department of Gastroenterology, Aichi Cancer Center Hospital, Nagoya;

¶¶¶Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Shinagawa;

###Department of Surgery, Kyorin University School of Medicine, Mitaka;

****Department of Gastroenterology, Keio University School of Medicine, Shijuku;

††††Department of Gastroenterology, Aizu Medical Center, Fukushima Medical University, Fukushima; and

‡‡‡‡Department of Gastroenterology and Hepatology, Kyoto University Graduate School of Medicine, Kyoto, Japan.

Received for publication April 10, 2018; accepted October 23, 2018.

Address correspondence to: Tetsuya Ito, MD, PhD, Department of Gastroenterology, Shinshu University School of Medicine, 3-1-1 Asahi, Matsumoto 390-8621, Nagano, Japan (e-mail:

This work was supported partially by the Research Program of Intractable Disease provided by the Ministry of Health, Labor, and Welfare of Japan and in part by grants-in-aid for Scientific Research from the Ministry of Education, Science, Sports, and Culture of Japan (23591012).

The authors declare no conflict of interest.

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