Case Report: A case of new-onset retroperitoneal aggressive fibromatosis after resection of solid pseudopapillary tumor of the pancreas and review of the literature.

Aggressive fibromatosis is a rare tumor known for its intensive local invasion and postoperative recurrence. Tumors may occur incidentally or be associated with familial adenomatous polyposis. We report a case of new aggressive fibromatosis after removal of solid pseudopapillary tumor of pancreas. The patient underwent two laparotomies, the first one was radical resection, and the second was R1 resection due to invasive fibromatosis invading the surrounding blood vessels, and titanium clips were indwelled at the resection margin for further radiotherapy treatment. Both pathological diagnoses of the patients were confirmed. There have been no previous reports of a relationship between solid pseudopapillary tumor of the pancreas and aggressive fibromatosis. We believe that surgical R0 resection should continue to be sought after surgery. If there is recurrence or metastasis, radiotherapy or targeted drug therapy such as sorafenib (400 mg/day) should be performed.