The diagnosis of PRMS was established postoperatively based on histological and immunohistochemical findings, which revealed positive staining for desmin and MyoD1 (myogenic differentiation 1) and negative staining for h-caldesmon and SMA (smooth muscle actin), helping to exclude smooth muscle tumors such as leiomyosarcoma. Here, MYOD1 is linked to leiomyosarcoma.