Soft tissue myxofibrosarcoma in the right lower limb: a case report.

OBJECTIVE: The objective of this case report is to present a rare case of soft tissue myxofibrosarcoma in the right lower limb, emphasizing the diagnostic delay, therapeutic decisions, and clinical outcome over a 24-year course. BACKGROUND: Myxofibrosarcoma is a rare and aggressive soft tissue sarcoma that often affects older adults. It may be misdiagnosed due to its histological resemblance to benign tumors such as schwannomas and is associated with high local recurrence and delayed distant metastasis. CASE PRESENTATION: A 47-year-old mestizo male patient presented with a progressively enlarging, firm mass in the right thigh, initially associated with paresthesias in the right lower limb. He underwent surgical resection, with initial histological diagnosis of benign schwannoma. Adjuvant radiotherapy and brachytherapy were administered, and 14 years later, he developed local symptoms again. After 20 years, histopathology confirmed high-grade myxofibrosarcoma. Despite further surgery, chemotherapy, and radiotherapy, he developed bilateral pulmonary metastases. Amputation and palliative therapy followed, and he died at age 50 years due to metastatic complications. CONCLUSION: This case illustrates the diagnostic and therapeutic challenges of MFS. It highlights the importance of early pathological confirmation, long-term surveillance, and the value of integrated, multidisciplinary treatment. Molecular profiling may aid future therapeutic decisions in advanced stages.