Primary Mesenchymal Tumors of the Pancreas: Single-center Experience over 16 Years

Objective: Primary mesenchymal tumors of the pancreas are extremely rare and no comprehensive study of this class of tumors has been previously performed.

Methods: Twenty cases of the primary mesenchymal tumors of the pancreas were selected and compared clinicopathologic variables with consecutively resected 500 pancreatic ductal adenocarcinomas.

Results: Finally, 20 (0.3%) cases were confirmed as primary mesenchymal tumors. The 14 (70%) cases of benign/borderline tumors included 4 cases of fibromatoses, 2 cases of cavernous hemangiomas, 2 cases of schwannomas, 2 cases of solid and cystic hamartomas, 2 cases of solitary fibrous tumors, 1 case of inflammatory myofibroblastic tumor, and 1 case of angiomyolipoma. The 6 (30%) cases of sarcomas comprised 3 cases of undifferentiated/unclassified sarcomas, 1 case of leiomyosarcoma, 1 case of Ewing sarcoma/primitive neuroectodermal tumor, and 1 case of atypical lipomatous tumor/well-differentiated liposarcoma. When compared with the 500 ductal adenocarcinomas, the 3 surgically resected sarcomas were larger (mean, 5.8 cm vs 3.6 cm; P = 0.02); however, no difference in median survival time was observed between patients with sarcoma (23 months) and patients with ductal adenocarcinoma (16 months).

Conclusions: First, primary mesenchymal tumors of the pancreas are extremely rare. Second, several primary mesenchymal tumor types can be observed in the pancreas. Understanding these rare disease entities will help ensure their correct diagnosis.