Aggressive Sporadic Renal Angiomyolipoma With Tumor Thrombus Extending Into the Inferior Vena Cava, Right Atrium, and...

BACKGROUND Renal angiomyolipoma (AML) is a typically benign mesenchymal tumor with an indolent clinical course. Rarely, AML demonstrate aggressive vascular invasion, most commonly in association with tuberous sclerosis complex (TSC). Intracardiac extension, particularly into the right ventricle, is exceptionally uncommon in sporadic cases and presents significant diagnostic and surgical challenges. CASE REPORT A 36-year-old woman with a history of rheumatoid arthritis presented with progressive left upper-quadrant abdominal pain, nausea, and back discomfort. Cross-sectional imaging revealed a massive left renal angiomyolipoma measuring 19.5×18.0×10.5 cm, with a contiguous tumor thrombus extending from the left renal vein through the inferior vena cava into the right atrium, intermittently prolapsing across the tricuspid valve into the right ventricle. Echocardiography confirmed a mobile intracardiac mass without evidence of valvular obstruction. Genetic testing was negative for TSC1 and TSC2 mutations, consistent with a sporadic angiomyolipoma. The patient underwent successful en bloc left radical nephrectomy with complete venous thrombectomy and inferior vena cava reconstruction through a coordinated multidisciplinary approach. Final pathology confirmed complete excision with negative margins and absence of epithelioid features. CONCLUSIONS This case was an exceptionally rare presentation of sporadic renal angiomyolipoma with extensive intracardiac extension into the right ventricle. It demonstrates that significant vascular and cardiac involvement can occur even in the absence of TSC-associated genetic mutations or epithelioid histology, thereby challenging traditional assumptions regarding AML behavior. These findings underscore the importance of early recognition, comprehensive imaging, and individualized operative planning in the management of complex AML presentations. Given the potential for aggressive progression in otherwise benign tumors, close long-term radiographic surveillance remains essential.