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JPTM > Ahead-of Print

doi: https://doi.org/10.4132/jptm.2018.10.25    [Epub ahead of print]
Coexisting Mucinous Cystic Neoplasm of the Pancreas and Type 1 Autoimmune Pancreatitis
Mee-Jeong Kim1, Tae Jun Song2, Hyoung Jung Kim3, Song-Cheol Kim4, Myung-Hwan Kim2, Seung-Mo Hong1
1Department of Pathology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
2Department of Gastroenterology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
3Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
4Department of Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
Corresponding Author: Seung-Mo Hong ,Tel: +82-2-3010-4558, Fax: 82-2-472-7898, Email: smhong28@gmail.com
Received: October 1, 2018;  Revised: October 17, 2018  Accepted: October 24, 2018.  Published online: November 14, 2018.
ABSTRACT
Type 1 autoimmune pancreatitis (AIP1) is an IgG4-related systemic disease that mimics tumors. We report a rare case of AIP1 accompanied by mucinous cystic neoplasm (MCN). A pancreatic lesion was incidentally detected in a woman in her 60s. After 6 years of follow-up, the lesion abruptly increased in size. Computed tomography showed a 3.5-cm unilocular cyst in the tail of the pancreas and distal pancreatectomy was performed. On microscopic examination, the cyst was lined by mucinous and non-mucinous epithelial cells with mild cytologic atypia. The surrounding stroma comprised ovarian-type spindle cells with progesterone receptor positivity. The pericystic pancreas exhibited multifocal lymphoid follicles, lymphoplasmacytic infiltrations, obliterative phlebitis, and storiform fibrosis. IgG4-positive plasma cell infiltration (215 cells/HPF) and the IgG4/IgG ratio (57%) were increased. Cases of MCN coexisting with AIP1 are extremely rare; only two such cases have been reported in the English-language literature. This third case featured low-grade MCN with AIP1.
Key Words: Pancreas; mucinous cystic neoplasm; autoimmune pancreatitis