Pleomorphic Rhabdomyosarcoma of the Uterine Corpus in an Adult Who Underwent Multi-gene Panel Testing.

Background/aim: Rhabdomyosarcoma (RMS) is the most common malignant soft tissue tumor in children. Adult primary RMS of gynecological origin is a rare condition and uterine RMS is an aggressive malignancy with a poor prognosis. The genetic variants associated with uterine RMS in adults have yet to be fully elucidated, and there is no established therapeutic strategy for rare tumors.

Case report: A 69-year-old Japanese woman was referred to our hospital with abdominal bloating. Imaging examination revealed a tumor with diameter of 85 mm located in the uterus and multiple regional lymph node metastases. Biopsy of the uterine corpus indicated possible uterine carcinosarcoma or RMS. Following debulking surgery, the patient was diagnosed with stage IVB pleomorphic RMS. The patient was treated with two courses of doxorubicin every three weeks and one course of combination chemotherapy with vincristine, actinomycin, and cyclophosphamide. Because of rapid progression of the disease, we decided to perform multi-gene panel testing to determine the most effective therapeutic strategy. However, no therapeutic plan based on genetic information was identified. The patient with chemotherapy-refractory RMS died 11 weeks after surgery.

Conclusion: Our patient had advanced uterine RMS with an unresectable tumor that was resistant to chemotherapy, resulting in poor outcomes. Despite conducting multi-gene panel testing, no tailored therapeutic approach based on genetic information was found. This case highlights the challenges in managing uterine RMS in adults and underscores the urgent need for further research to identify effective treatment modalities.