Epithelioid Angiomyolipoma: An Overview of Five Cases with the Concept of PEComa

類上皮型血管肌肉脂肪瘤：以血管旁類上皮細胞腫瘤家族觀念綜觀五個病例

黃厚期(Hou-Chi Hwang)；黃振義(Jen-I Hwang)；熊小澐(Siu-Wan Hung)；龔敏凱(Mein-Kai Gueng)；楊啓順(Chii-Shuenn Yang)；陳啓昌(Clayton Chi-Chang Chen)

中華放射線醫學雜誌

33卷4期（2008 / 12 / 01）

253 - 260

英文

血管肌肉脂肪瘤是一種少見的軟組織瘤，最多起源自腎臟，亦可影響肝臟或身體其他器官。長期以來被認為是一種良性的過誤瘤，但最近幾年來研究認為，這是一種起源自血管旁類上皮細胞的新生性腫瘤。類上皮型血管肌肉脂肪瘤是一種罕見的次分型，是由類上皮細胞所構成，具有潛在可能的惡性表現，臨床上診斷易與其他惡性腫瘤混淆，產生誤診。HMB-45陽性的免疫組織化學反應為其診斷依據。類上皮型血管肌肉脂肪瘤目前已被歸屬在血管旁類上皮細胞腫瘤家族。 這裡我們描述了五個類上皮型血管肌肉脂肪瘤的病例，其中一例源自左上後腹腔，兩例源自腎臟，兩例源自肝臟，其臨床和影像學的表現如下： 左上後腹腔之病例因腫瘤巨大，在影像上無法確認其起源，故術前必需與惡性脂肪肉瘤做鑑別診斷。長於腎臟的兩個病例，其臨床上的表現為腹部可觸診到之腫瘤或合併急性腹痛，這兩例皆於術前診斷，因其影像上的腫瘤脂肪成分與典型的臨床表現。其中一例長於腎臟的病人合併結節性硬化症，之後發展成肝臟及腹腔轉移，最後死於疾病。長於肝臟的兩個病例，術前皆誤診為肝細胞癌，主因其影像上的表現不具腫瘤脂肪成分，而類上皮型血管肌肉脂肪瘤在肝臟的發生率為罕見所致。 因為近來研究顯示其潛在可能的惡性表現，放射線醫師必須了解此種罕見的類上皮型血管肌肉脂肪瘤之疾病，以利診斷。

Angiomyolipoma is a well-known rare soft tissue tumor involving the kidneys, liver and other organs. Long believed to be a benign hamartoma, angiomyolipoma is now considered a neoplasm that arises from perivascular epithelioid cell. Epithelioid angiomyolipoma is potentially malignant variant of angiomyolipoma characterized by epithelioid cells that mimic mal ignant tumors arising from the organs. Immunoreactivity with HMB-45 is helpful for its identification. It is now considered to be a part of PEComa family and perivascular epithelioid cells (PEC) are recently proposed to be its most common progenitor cells. Here we give an overview of five rare cases with epithelioid angiomyolipoma, one in left upper retroperitoneum, two in liver and two in kidney, focusing on clinical presentations and imaging findings. The case in left upper retroperitoneum was pre-operative differentiated from retroperitoneal liposarcoma due to huge space-occupying lesion of uncertain origin. The two cases in kidneys were clinically manifested as palpable abdominal mass and/or acute abdominal pain; both were pre-operative diagnosed by tumoral fat content and/or the classic clinical features. One case with maliganant epithelioid angiomyolipoma of kidney associated with tuberous sclerosis (TS) developed metastases to liver and retroperitoneum and finally died of the disease. The two cases of hepatic epithelioid angiomyolipoma were pre-operative misdiagnosed as hepatocellular carcinoma (HCC) due to its rare incidence and less fat component of the tumor with similar imaging finding to HCC. In conclusion, we radiologists should be aware of the existence of rare epithelioid variant of angiomyolipoma which belongs to the PEComa family arising in different origins and its potential malignant behavior.