A Rare Presentation of a Large Pleomorphic Rhabdomyosarcoma of the Inferior Vena Cava (IVC): A Case Report.

Rhabdomyosarcoma (RMS) in adults is a rare, aggressive malignant tumour of mesenchymal origin with a poor prognosis. Hematoxylin and eosin (H&E) staining showing cellular population of large, rounded epithelioid, rhabdoid, plump spindled, and bizarre multinucleate tumour giant cells, as well as immunohistochemistry showing extensive staining of the atypical tumour cells for desmin and myogenic differentiation 1 gene (MyoD1) with multifocal coexpression of myogenin, are characteristic of RMS. We present a rare and unique case of a male in his 50s who presented with a two-week history of right-sided intermittent dull groin and back pain associated with bilateral lower limb swelling, who was diagnosed with a 9 cm right retroperitoneal pleomorphic RMS involving the inferior vena cava (IVC), causing complete IVC occlusion. He underwent an extensive en bloc resection of the tumour. We also discuss the signs, symptoms, relevant investigations, and various treatment options in managing a patient with pleomorphic RMS.