Misdiagnosis of primary pleomorphic rhabdomyosarcoma of the right thigh in a young adult: A case report.

Pleomorphic rhabdomyosarcoma (PRMS) is a rare type of soft tissue tumor accounting for <2% of all adult sarcomas. The present study describes a case of a 28-year-old male patient with primary PRMS of the right thigh. The patient was initially diagnosed with a schwannoma and underwent conservative therapy at a local hospital. At the 6-month follow-up, the patient reported a marked increase in the size of the mass. Finally, the patient underwent fine-needle aspiration and total tumor resection. The tumor measured 11×9×5 cm in size and was located in the vastus intermedius muscle. According to histological and immunohistochemical findings, a diagnosis of PRMS was confirmed by an expert pathology consultant. Postoperative follow-up at 3 months revealed no evidence of recurrent disease or residual side effects from therapy. However, it is imperative that such cases are closely monitored following surgery, in order to evaluate the long-term efficacy of the procedure, since misdiagnosis may increase the risk of recurrence and metastasis. The present case is noteworthy due to the misdiagnosis of PRMS, the large size of the mass and the young age of the patient.