Benign Mesenchymal Tumor of the Pancreas: A Case Report and Review of Literature

Abstract

Purpose: Pancreatic mesenchymal neoplasia are very rare. Dedicated pancreatic imaging studies and endoscopic ultrasound with fine needle aspiration (EUS-FNA) are important in diagnosis and management of these pancreatic lesions. We report a case of a benign pancreatic mesenchymal tumor causing extrinsic pancreatic duct dilatation presenting with non-specific gastrointestinal symptoms. A 63-year-old African-American lady without significant past medical or family history presented with nonspecific lower abdominal pain, bloating sensation and mild constipation of 3 months duration. Physical examination was unremarkable. Laboratory data was within normal limits. A contrast enhanced CT scan of the abdomen, done to rule out any organic pathology, showed a diffusely dilated pancreatic duct without any obstructing mass was identified. An MRI/MRCP was done which confirmed the abnormal dilatation of the pancreatic duct (up to 6 mm) within the pancreatic body and tail, secondary to extrinsic compression by a 7 mm mass within the pancreatic body. There was no intra or extra hepatic biliary ductal dilatation. EUS showed a hypoechoic, solitary, 11.2×9 mm, ill-defined mass at the junction of head and neck of the pancreas, completely encircling and possibly compressing the main pancreatic duct with upstream dilatation. No pancreatic ductal thickening, irregularity or intra-ductal calcification was noted. There was no evidence of chronic pancreatitis as per EUS criteria. The endo-sonographic pancreatico-biliary exam was otherwise normal. The EUS-FNA revealed few groups of spindle cells, with features suggestive of spindle cell neoplasm without malignancy, consistent with benign pancreatic mesenchymal tumor. While the majority of primary pancreatic tumors are adenocarcinomas, endocrine tumors are uncommon and mesenchymal tumors are rare. Their diagnoses can be challenging. They are usually asymptomatic depending on the location, size of the tumor and lack of mucosal involvement. The clinical symptoms include abdominal pain, early satiety, flatulence, ileus, bleeding, anemia and weight loss. The diagnosis can be incidental after radiologic imaging. EUS-FNA is a useful technique for in-vivo imaging and tissue acquisition for diagnosing these tumors. The cytologic differential diagnosis for spindle cell proliferation includes leiomyoma, schwannoma, GIST, fibromatosis, inflammatory fibroid polyps, solitary fibrous tumor and gastrointestinal muscularis sampling.