Challenges in Diagnosing Rare Retroperitoneal Tumors: A Case Report of Extrarenal Giant Angiomyolipoma.

Introduction: Extrarenal angiomyolipomas are extremely rare tumors, with only isolated reports in the literature. Their diagnosis is challenging as these lesions are often misdiagnosed as more common retroperitoneal tumors. This report presents a case of a retroperitoneal extrarenal angiomyolipoma, emphasizing its clinical, imaging, and histopathological features to facilitate accurate diagnosis and avoid errors. Case Presentation: A 58-year-old male with a history of benign prostatic hyperplasia presented with progressive abdominal distension and weight gain. Imaging studies revealed a giant retroperitoneal mass displacing the left kidney and abdominal aorta. A core needle biopsy initially suggested a well-differentiated liposarcoma T4N0M0, leading to neoadjuvant chemotherapy with doxorubicin and ifosfamide. Surgical resection of a 20 × 30 × 25-cm mass was performed. Histopathological and immunohistochemical analysis of the specimen confirmed the diagnosis of retroperitoneal extrarenal angiomyolipoma. Chemotherapy was discontinued, and the patient remains stable under follow-up. Discussion and Conclusion: Retroperitoneal extrarenal angiomyolipomas are rare, presenting significant diagnostic challenges due to their resemblance to other retroperitoneal neoplasms such as liposarcomas. This case highlights the importance of comprehensive imaging, histopathological examination, and immunohistochemical studies for accurate diagnosis. Increased awareness of this entity can help clinicians avoid unnecessary treatments and ensure appropriate management of similar cases.