Lu Shi-Qi, Lv Wei, Liu You-Jun, Deng Huan
Medical College, Nanchang University, Nanchang 330006, Jiangxi Province, China.
Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu 610044, Sichuan Province, China.
World J Clin Cases. 2023 Jan 16;11(2):417-425. doi: 10.12998/wjcc.v11.i2.417.
Angiomyolipoma (AML), the most common benign tumor of the kidney, is usually composed of dysmorphic blood vessels, smooth muscle, and mature adipose tissue. To our knowledge, AML with cystic degeneration has rarely been documented. Cystic degeneration, hemorrhage, and a lack of fat bring great challenges to the diagnosis.
A 60-year-old man with hypertension presented with a 5-year history of cystic mass in his left kidney. He fell 2 mo ago. A preoperative computed tomography (CT) scan showed a mixed-density cystic lesion without macroscopic fat density, the size of which had increased compared with before, probably due to hemorrhage caused by a trauma. Radical nephrectomy was performed. Histopathological studies revealed that the lesion mainly consisted of tortuous, ectatic, and thick-walled blood vessels, mature adipose tissue, and smooth muscle-like spindle cells arranged around the abnormal blood vessels. The tumor cells exhibited positivity for human melanoma black-45, Melan-A, smooth muscle actin, calponin, S-100, and neuron-specific enolase, rather than estrogen receptor, progesterone receptor, CD68, and cytokeratin. The Ki-67 labeling index was less than 5%. The final diagnosis was a fat-poor renal AML (RAML) with prominent cystic degeneration.
When confronting a large renal cystic mass, RAML should be included in the differential diagnosis.
肾血管平滑肌脂肪瘤（AML）是最常见的肾脏良性肿瘤，通常由形态异常的血管、平滑肌和成熟脂肪组织组成。据我们所知，伴囊性变的AML鲜有文献记载。囊性变、出血及脂肪缺失给诊断带来了巨大挑战。
一名60岁高血压男性，左肾囊性肿物病史5年。2个月前摔倒。术前计算机断层扫描（CT）显示为混合密度囊性病变，无肉眼可见脂肪密度，其大小较之前增大，可能系外伤所致出血。行根治性肾切除术。组织病理学研究显示，病变主要由迂曲、扩张且壁增厚的血管、成熟脂肪组织以及围绕异常血管排列的平滑肌样梭形细胞组成。肿瘤细胞对人黑素瘤黑色素-45、Melan-A、平滑肌肌动蛋白、钙调蛋白、S-100和神经元特异性烯醇化酶呈阳性反应，而对雌激素受体、孕激素受体、CD68和细胞角蛋白呈阴性反应。Ki-67标记指数小于5%。最终诊断为脂肪含量少的肾AML（RAML）伴显著囊性变。
面对较大的肾囊性肿物时，鉴别诊断应考虑RAML。
