巨大腎臟上皮樣血管平滑肌脂肪瘤伴隨腫塊效應：一個病例報告及文獻回顧

楊鎧伍¹、賴韋宏¹

嘉義基督教醫院 外科部 泌尿科¹

Giant renal Epithelioid Angiomyolipoma with mass effect: A case report and review of the literature

Kai-Wu Yang¹，Wei-Hong Lai ¹

Divisions of Urology, Department of Surgery, Chia-Yi Christian Hospital¹

Introduction: 

   Epithelioid angiomyolipoma (EAML, perivascular epithelioid cell tumor) is an uncommon primary renal tumor that can exhibit malignant behavior with local recurrence and/or metastasis, although there remain limited data for prediction of these outcomes. Here we presented a case of renal Epithelioid Angiomyolipoma with mass effect in the initial presentation.

Case presentation: 

    A 68-year-old female with uncontrolled rheumatoid arthritis due to medication side effects was diagnosed with a 10 cm left renal cyst in March 2023. The patient opted for observation at that time. However, she later experienced worsening anemia (hemoglobin around 8 g/dL) and increased left abdominal bulging, accompanied by frequent urination and constipation. A follow up CT scan in June 2024 revealed that the cyst had enlarged to 17 x 12 cm with thickened irregular septa and soft tissue components. She reported a 6 kg weight loss over the past year. Physical examination revealed a large, non-tender left upper abdominal mass. Comprehensive renal function test indicated a differential function of 21% for the left kidney and 79% for the right, respectively. The patient had no clinical symptoms or signs of tuberous sclerosis complex. Laboratory tests revealed renal function within normal limits. Transperitoneal hand-assisted laparoscopic radical nephrectomy was performed. The dissected surface of renal tumor shows fibrous wall and hemorrhagic content with blood clots measuring up to 10 cm in dimension. histopathology examination findings were consistent with the diagnosis of EAML and positive stain in Melan-A and Cathepsin K. The patient showed no tumor recurrence during follow-up, and her recovery was uneventful.

Discussion:

   Renal epithelioid angiomyolipomas (EAMLs) are a rare subtype of perivascular epithelioid cell tumors, comprising 4.6% of all renal angiomyolipomas (AMLs), with characterized by atypical epithelioid cells and may exhibit aggressive behavior, including local invasion, distant metastasis, and local recurrence after excision. These tumors are often associated with genetic mutations in tuberous sclerosis complex (TSC), and linked to several adverse prognostic factors, including tumor size greater than 7 cm and extra renal extension. Treatment primarily involves nephrectomy due to the malignancy risk, although responses to chemotherapy remain unvalidated in large studies. Neoadjuvant or adjuvant mTOR inhibitors like everolimus may improve clinical outcomes.

Conclusion: 

        Epithelioid angiomyolipoma (EAML) is an uncommon renal tumor with diverse imaging characteristics that may resemble renal cell carcinoma. Consequently, EAML must be included in the differential diagnosis of any sizable renal mass with histological features of minimal fat, necrosis, and hemorrhage. The preferred treatment approach is nephrectomy.