Huge Primary Intermediate-grade Myofibroblastic Sarcoma in the Retroperitoneum.

Abstract

Myofibroblastic sarcoma is exceedingly rare, with low-grade features in most cases, and rarely involves the retroperitoneum. The 2020 World Health Organization (WHO) classification of soft tissue tumours still lists only low-grade myofibroblastic sarcoma and shows no consensus on the definitions of high- and intermediate-grade myofibroblastic sarcomas, in contrast to the 2013 WHO classification. Surgical resection of the tumour and adjacent structures is the standard of care for most patients, and intermediate- and high-grade myofibroblastic sarcomas have very poor survival. We describe a patient with intermediate-grade myofibroblastic sarcoma in the retroperitoneum, who underwent en bloc resection and ureteroplasty without adjuvant therapy and was free of pain and any other discomfort during 19 months of follow-up. Key Words: Myofibroblastic sarcoma, Intermediate grade, Retroperitoneum, Surgery.