Adrenal incidentalomas are incidentally detected adrenal lesions on imaging, which have a variety of differential diagnoses, the most common being a non-functioning adenoma . Surgical intervention for these lesions is needed when there is hypersecretion, for lesions larger than 4 cm and smaller lesions with suspicious characteristics . Here we present a young woman who was incidentally found to have a right suprarenal mass with loss of fat planes with the inferior vena cava (IVC). She underwent resection of the tumour along with the posterior wall of IVC, which was primarily repaired . Her postoperative biopsy was suggestive of leiomyosarcoma arising from the IVC . In the absence of distant metastasis, the sole prognostic factor for this tumour is achieving negative margins through radical resection of the tumour with IVC resection . Retroperitoneal leiomyosarcomas should be considered as a differential diagnosis for larger lesions, especially those more than 10 cm.