Sustained Disease Control of High-Risk Metastatic Renal Epithelioid Angiomyolipoma through Multimodal Treatment Including Repeated Thoracic Resection and Systemic Therapy: A Case Report.

Introduction: Renal epithelioid angiomyolipoma (EAML) is a rare perivascular epithelioid cell tumor with malignant potential. Radiologic distinction from renal cell carcinoma (RCC) may be difficult in fat-poor cases, and standardized treatment strategies for metastatic disease have not been established. Case Presentation: A woman in her 30 s presented with a palpable right abdominal mass and anorexia. Contrast-enhanced computed tomography showed an 18-cm heterogeneous right renal mass and a 25-mm liver lesion suspicious for metastasis, without pulmonary metastasis at diagnosis. The pretreatment clinical stage was cT2bN0M1, stage IV. Imaging findings strongly suggested clear cell RCC, and the lesion was managed as presumed metastatic clear cell RCC. The International Metastatic RCC Database Consortium risk category was poor risk. Nivolumab plus cabozantinib was initiated without pretreatment biopsy. At Month 3, the primary tumor showed partial response and the liver lesion remained stable; however, cabozantinib became difficult to continue because of adverse effects, and right nephrectomy was performed in a setting analogous to deferred cytoreductive nephrectomy. Histopathology established renal EAML with pT2b disease, necrosis, mitotic count ≥2, atypical mitoses, severe nuclear atypia, smooth muscle actin negativity, and Ki-67 ≥ 10%, fulfilling six of seven adverse prognostic factors and indicating high-risk disease. Everolimus induced partial response of a new lung metastasis. Subsequent liver and bilateral lung metastases were managed with systemic therapy and staged thoracoscopic resections. Later, isolated subcarinal mediastinal lymph node progression was treated by thoracoscopic resection. The patient remains recurrence-free for 8 months on everolimus. Conclusion: Metastatic renal EAML lacks a standardized treatment strategy. This case suggests that durable disease control may be achievable in selected high-risk patients through individualized multimodal treatment integrating systemic therapy with repeated local treatment for thoracic oligoprogressive lesions.