胃腸および消化器系

抽象的な

Groove Pancreatitis: A Malignant Masquerade in the Duodenum

Karin Eshagh, Chris M Reid, Michael Chan, Grace Y Lin, Thomas Savides and Jason K Sicklick

Groove pancreatitis is a rare form of chronic pancreatitis that has been described by several names including para-duodenal wall cyst, pancreatic hamartoma of the duodenum, cystic dystrophy of heterotopic pancreas, and myoadenomatosis. It is characterized microscopically by the presence of a pseudocyst arising from the “groove” between the duodenum, common bile duct, and pancreatic head. It is thought to be caused by functional and/or anatomical minor papilla obstruction from viscous pancreatic secretions. In turn, this leads to impaired pancreatic enzyme outflow, Brunner’s gland proliferation, and resultant pancreatitis. This often appears as a submucosal mass in the region. Thus, the differential diagnosis ranges from benign pathologies such as Brunner’s gland hyperplasia, leiomyoma, and schwannoma to malignant pathologies such as gastrointestinal stromal tumor and ampullary carcinoma. Herein, we present a case of a middle aged male smoker with a remote history of alcohol abuse that presented with one month of epigastric pain associated with bilious emesis and weight loss. Computed tomography (CT) and endoscopic ultrasound (EUS) revealed a submucosal cystic mass that was obstructing the second portion of the duodenum. Cytology demonstrated crowded groups of atypical epithelioid and spindle cells that were suspicious for a neoplasm. The patient subsequently underwent pancreaticoduodenectomy in order to relieve his duodenal obstruction, as well as to establish a definitive tissue diagnosis. Despite the use of multiple imaging modalities including CT and EUS with fine needle aspirates, the final diagnosis of groove pancreatitis was only made following resection. This case now demonstrate that groove pancreatic often mimics submucosal duodenal tumors and malignant periampullary cancers clinically, radiographically, endoscopically, and cytologically.