Primary mesenchymal tumors of the pancreas in a single center over 15 years

Abstract

In total, 95% of primary tumors in the pancreas are epithelial tumors; primary mesenchymal tumors at this site are extremely rare. At present, only one comprehensive study about these rare tumors has been performed. Another retrospective analysis of these rare tumors is performed in the present study, which, to the best of our knowledge, is the first to be performed in China. In the present study, 10 patients that underwent resection for primary mesenchymal tumors of the pancreas were identified in a 15-year period at the Chinese Academy of Medical Sciences and Peking Union Medical College, which accounted for 0.51% of the total surgically resected primary tumors of the pancreas at this hospital. Among the 10 patients, 7 patients (70%) were diagnosed with benign/borderline tumors, and the remaining 3 patients (30%) were diagnosed with malignant tumors. It was a unique finding of the present study that the preoperative diagnosis was frequently a misdiagnosis, in terms of the specific pathological diagnosis. Therefore, although primary mesenchymal tumors of the pancreas are extremely rare, they should be considered in order to make the correct preoperative diagnosis. Contrarily to a previous study, in the present study, the most common benign tumor was not desmoid tumor, but solitary fibrous tumors; the most frequent primary sarcoma was not undifferentiated/unclassified sarcoma either. In conclusion, the present study aids the understanding of these rare tumors; however, primary mesenchymal tumors of the pancreas require additional exploration in the future.

Keywords: misdiagnosis; pancreas; prevalence; primary mesenchymal tumor.

Figure 1.

Kaplan-Meier survival analysis of patients with primary benign/borderline and malignant pancreatic mesenchymal tumors.

Figure 2.

Representative images of benign/borderline and malignant mesenchymal tumors of the pancreas. (A-B) Undifferentiated pleomorphic sarcoma (case 10). (A) Macroscopy of the tumor showed a solid mass. (B) Microscopically, the tumor was composed of giant cells with evident cytological atypia. (C-E) Solitary fibrous tumor (case 4). (C) Macroscopy of the tumor showed a tan-white solid mass. (D) The tumor was composed of spindle cells with a combination of hypocellular and hypercellular areas. (E) Cluster of differentiation 117 was diffusely stained in tumor cells diffusely. (F) Schwannoma (case 6). (G-H) Malignant gastrointestinal stromal tumor (case 5). (G) Epithelioid tumor cells of the tumor. (H) Brisk mitosis in the center of the tumor.