Swelling of the vaginal mucosa is a symptom caused by the subcutaneous development of embryonal rhabdomyosarcoma. It is caused by the subcutaneous production of embryonal rhabdomyosarcoma. Let’s look at the specific information about its pathology. Embryonal rhabdomyosarcoma is a primitive malignant soft tissue sarcoma with phenotypic and biological features of embryonic skeletal muscle. It accounts for approximately 2/3 of rhabdomyosarcomas and is more common in children and adolescents, with a two-peak age distribution, i.e., postnatal and late adolescent, at a mean age of 5 years. They occur in the head, neck, genitourinary tract, and retroperitoneum. Transverse myxosarcoma, the cause of which is unknown, is a malignant tumor of soft tissue composed of variously differentiated rhabdomyoblasts. The disease may be associated with genetic factors, chromosomal abnormalities, and gene fusions. Rhabdomyosarcoma is a malignant tumor originating from rhabdomyoblasts or mesenchymal cells differentiated to rhabdomyoblasts, and is the most common type of soft tissue sarcoma in children. The incidence of rhabdomyosarcoma is the third most common soft tissue sarcoma after malignant fibrous histiocytoma and liposarcoma.