Abstract
Spindle cell rhabdomyosarcoma (SC-RMS) is an unprecedented version of embryonal rhabdomyosarcomas (RMSs) that emerges from the mesenchyme with the capacity to differentiate into skeletal muscle cells. Retroperitoneal RMS is extremely rare in the adult population. We present the case of a primary spindle cell retroperitoneal RMS with compression features. Investigation-based diagnosis of RMS is difficult due to the lack of specificity of clinical findings. Radiology does not help in making an accurate diagnosis. Surgical removal of the tumor followed by chemotherapy and radiotherapy is the best possible treatment for RMS in adults. SC-RMS has a poor long-term prognosis. To our knowledge, such cases of retroperitoneal SC-RMS compressing the abdominal viscera and resulting in hydroureteronephrosis have never been reported before.