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 high-power field) 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.
Citations
Citations to this article as recorded by
Histological features of autoimmune pancreatitis and IgG4-related sclerosing cholangitis with a correlation with imaging findings Kenji NOTOHARA Choonpa Igaku.2023; 50(1): 55. CrossRef
Imaging Features and Risk Factors of Pancreatic Cystic Lesions Complicating
Autoimmune Pancreatitis: A Retrospective Study Bin-Bin Zhang, Xin-Meng Hou, Yu-Qi Chen, Jian-Wei Huo, Er-Hu Jin Current Medical Imaging Formerly Current Medical Imaging Reviews.2023;[Epub] CrossRef
Histological features of autoimmune pancreatitis and IgG4-related sclerosing cholangitis with a correlation with imaging findings Kenji Notohara Journal of Medical Ultrasonics.2021; 48(4): 581. CrossRef
Mucinous cystic neoplasm of the pancreas with type-1 autoimmune pancreatitis-like lesion Kevin Gowing, David F. Schaeffer, Hui-Min Yang Human Pathology: Case Reports.2019; 18: 200339. CrossRef