Primary alveolar rhabdomyosarcoma of retrorectal-presacral space in an adult patient: A case report of an uncommon tumor with rare presentation.

Rationale:Rhabdomyosarcoma (RMS) has known as a highly malignant soft tissue sarcoma, representing 5% to 10% of all solid tumors in childhood. Alveolar rhabdomyosarcoma (ARMS) of the retrorectal-presacral space is an extremely rare lesion for adult, no study has been reported in the English literature.Patient concerns:A 51-year-old male presented with abdominal pain for 1 month, significantly worse when having a bowel movement.Diagnosis:Computed tomography (CT) and magnetic resonance imaging (MRI) of the pelvis showed a solid-cystic, enhancing lesion of dimension located in retrorectal-presacral space. The surgical specimen was reported as ARMS after pathological evaluation.Interventions:The tumor was complete surgical resection, and after surgery, the patient was treated with combination chemotherapy.Outcomes:At 23 months follow up, the patient was asymptomatic with no evidence of metastases or local recurrence.Lessons:Improvements in imaging in addition to early surgical intervention and chemotherapy treatment are crucial to improve survival chances against RMS.