Mesenchymal tumors involving the pancreas: a clinicopathologic analysis and review of the literature

Abstract

Objective: Most pancreatic tumors are epithelial, and, among these, more than 90% are of ductal origin. However, a variety of mesenchymal tumors may involve the pancreas and may manifest different clinicopathological characteristics. The literature on mesenchymal tumors in the pancreas is largely limited to individual case reports or analyses of small series, predominantly focusing on radiologic features. Material and Method:Authors' institutional and consultation databases were reviewed to identify the mesenchymal tumors involving the pancreas.Results: Forty cases were identified; twenty-five (63%) tumors were benign/borderline, and the remaining fifteen (37%) were malignant. Of the benign/borderline tumors; 9 were solitary fibrous tumors, 6 gastrointestinal stromal tumors (GISTs), 4 schwannomas, 2 desmoid type fibromatosis, 1 lymphangioma, 1 ganglioneuroma, 1 inflammatory myofibroblastic tumor, and 1 low grade mesenchymal neoplasm. Malignant tumors included 6 cases of leiomyosarcomas, 4 liposarcomas, 2 rhabdomyosarcomas, 1 epithelioid angiosarcoma, 1 malignant peripheral nerve sheet tumor, and 1 undifferentiated pleomorphic sarcoma. Four cases (multicystic schwannoma, desmoid fibromatosis, lymphangioma and inflammatory myofibroblastic tumor) were preoperatively misdiagnosed as a primary epithelial tumor of the pancreas. Conclusion:Mesenchymal tumors rarely involve the pancreas. They are usually benign/borderline neoplasms but may be diagnostically challenging, especially clinically/radiologically, as they may form cystic and/or large lesions in the pancreas. Mesenchymal tumors should be considered in both the clinical/radiological and pathological differential diagnosis of pancreatic lesions.

Solitary Fibrous Tumor of the Pancreas

“…Even though primary mesenchymal tumors of the pancreas are rare, various mesenchymal tumor types arising from pancreatic stromal tissue have been reported, including inflammatory myofibroblastic tumor, desmoid tumor, GIST, lymphangioma, cavernous hemangioma, angiomyolipoma, schwannoma, ganglioneuroma, leiomyosarcoma, rhabdomyosarcoma, liposarcoma, angiosarcoma, Ewing sarcoma/ primitive neuroectodermal tumor, undifferentiated/unclassified sarcoma. 28,34,50 However, experience with SFT is very limited. Our current understanding of this tumor is mainly based on individual case reports.…”

Metastatic pancreatic solitary fibrous tumor: A case report

“…Most pancreatic tumors are of epithelial origin, with more than 90% being pancreatic ductal adenocarcinomas[ 3 ]. However, tumors of mesenchymal origin can also involve the pancreas, accounting for 1%-2% of all tumors[ 3 ].…”

“…Most pancreatic tumors are of epithelial origin, with more than 90% being pancreatic ductal adenocarcinomas[ 3 ]. However, tumors of mesenchymal origin can also involve the pancreas, accounting for 1%-2% of all tumors[ 3 ]. Mesenchymal tumors can be derived from the connective, lymphatic, neuronal, and vascular tissues, and show different clinicopathologic manifestations and outcomes[ 3 ].…”

“…However, tumors of mesenchymal origin can also involve the pancreas, accounting for 1%-2% of all tumors[ 3 ]. Mesenchymal tumors can be derived from the connective, lymphatic, neuronal, and vascular tissues, and show different clinicopathologic manifestations and outcomes[ 3 ]. Primary mesenchymal tumors of the pancreas that are known to show benign or borderline behavior include schwannomas, inflammatory myofibroblastic tumors, hamartomas, and solitary fibrous tumors in order of frequency[ 4 ].…”

“…SFT is mostly found in the pleura but can also occur in non-pleural sites[ 2 ]. The pancreas is an extremely rare non-pleural localization for SFT, with the majority of the tumors being secondary lesions[ 3 , 4 ]. According to the case report Yamashita et al [ 5 ] published in 2019, 21 cases of primary and secondary SFTs of the pancreas were reported in the English literature.…”