Login to Access Video or Poster Abstract: MP67-05
Sources of Funding: NSC 105-2314-B-182-024-MY3

Introduction

Epithelioid angiomyolipoma (eAML) has been considered a malignant variant of angiomyolipoma (AML) since it was classified by World Health Organization in 2004. Recent studies have argued that the actual metastatic rate of eAML is very low. This retrospective study aims to analyze the aggressive behavior rate and describe the vast clinicopathalogical variety of eAML.

Methods

In Chang Gung Memorial Hospital, Taiwan, a total of 887 patients were diagnosed with AML from 2001 to 2016 according to the healthcare information system archive, including 21 cases of renal eAML. All of the cases were diagnosed according to tissue proof and immunohistochemical studies. The images, pathology and medical records of these 21 eAML cases were reviewed and summarized._x000D_

Results

In these 21 eAML cases, the average age was 43.1 (ranges from 18 to 64), including 6 males and 15 females. All 21 cases are not associated with tuberous sclerosis complex. The longest diameter of the tumors ranges from 1.3 to 20 centimeters (average 9.8 cm). Three of these cases had multiple tumors (single eAML and single AML coexist on the left kidney, clear cell renal cell carcinoma on the right and single eAML on the left, multiple AML on bilateral kidneys with single eAML on the left). Only one patient suffered from spontaneous haemorrhage. Two cases developed distant metastasis: one had nodules over bilateral lungs and left anterior mediastinum; the other had recurrence over liver and retroperitoneum one year after surgical intervention. Three cases had venous thrombus (two in renal vein and one in inferior vena cava) and received thrombectomy. All 21 cases received surgical intervention: 13 radical nephrectomy, 7 partial nephrectomy, one was found with retroperitoneal eAML arising from renal capsule thus undergone tumor excision without kidney involvement. The follow up period ranges from 1 to 143 months (average 51 months). Only 2 cases died from unrelated cause._x000D_

Conclusions

In our study, the rate of aggressive behavior is 24% (2 distant metastasis and 3 venous invasion in the 21 cases). Some noticeable accompanying characteristics including haemorrhage, coexisting with AML, coexisting with renal cell carcinoma are also seen in this series. The incidence of renal vein and inferior vena cava thrombus formation in our series is high (3 out of 21), therefore, detailed preoperative image evaluation is necessary.

Funding

NSC 105-2314-B-182-024-MY3