儿童血管周上皮样细胞瘤的CT、磁共振成像及临床病理特征

CT, magnetic resonance imaging and clinicopathological characteristics of perivascular epithelioid cell tumor in children

目的评价儿童血管周上皮样细胞瘤(PEComa)的CT、磁共振成像(MRI)和临床病理特征,以提高对该肿瘤的诊断水平。方法回顾性分析2019年3月至2022年4月首都医科大学附属北京儿童医院经病理确诊的6例儿童PEComa的CT、MRI和临床病理特征。结果患儿年龄1.7~11.9岁(平均7.6岁)。男女比例为1∶2。6例单发肿瘤发病部位分别见于肾脏(2例)、腹腔(2例)、盆腔(1例)和腹股沟(1例)。肿瘤边界清晰,呈类椭圆形(5例)或多结节样(1例),边缘见花边样或结节样改变(3例)。肿瘤长径4.8~15.9 cm(平均9.3 cm)。5例肿瘤表现出周围侵犯,2例存在淋巴结转移。2例患儿合并结节性硬化症。1例肿瘤为术后复发。CT平扫(6例)示肿瘤呈等/低密度,增强后呈不均匀渐进性强化。多数(5例)肿瘤见瘤内迂曲增粗血管影,少数(2例)见沙砾样钙化。肿瘤中心在MRI(3例)T1WI及T2WI上呈斑片样或结节样高信号,周边呈等肌肉信号,弥散加权成像(DWI)(b=800 s/mm2)上病灶周边部分弥散受限且增强后强化明显,中心部分呈等信号,增强后不强化或仅轻微强化。1例组织学分类为良性PEComa,5例为恶性PEComa。Melan-A和SMA的表达率分别为100.0%、83.3%。结论儿童PEComa的CT、MRI和病理表现存在一些特异性,常表现为腹盆腔内边界清楚的类椭圆形肿块,伴结节样边缘,可见瘤内迂曲增粗血管,增强后以周边强化为主,可有局部侵犯和远处转移,病理上以恶性病变居多,免疫组织化学上呈黑色素-肌肉双源性表达。

Objective To investigate the CT,magnetic resonance imaging(MRI)and clinicopathological cha-racteristics of perivascular epithelioid cell tumors(PEComas)in children,and improve the diagnostic accuracy of PEComas.Methods The CT,MRI and clinicopathological characteristics of 6 children confirmed with PEComas by histopathology caming from Beijing Children′s Hospital,Capital Medical University during March 2019 and April 2022 were retrospectively analyzed.Results The patients aged from 1.7 to 11.9 years old(with mean age of 7.6 years old).The male to female ratio was 1∶2.Of the 6 solitary tumors identified,2 cases were found in the kidney,2 cases in the abdominal cavity,1 case in the pelvic cavity,and 1 case in the groin.The solitary tumors had well-defined borders.Five solitary tumors were shaped like an ellipse and 1 solitary tumor was multinodular-shaped.Lace-like or nodular changes were observed at tumor margins(3 cases).The maximum diameters of the tumors ranged from 4.8 to 15.9 cm(mean value:9.3 cm).Five tumors showed peripheral invasion and 2 cases had lymph node metastasis.Two patients were complicated with tuberous sclerosis.One case suffered from tumor recurrence after operation.The tumors(6 cases)were isodensity or low density on the plain CT scan,and gradual heterogeneous enhancement was observed after injection of the contrast agent.A majority of the tumors had tortuous(5 cases)and thickened blood vessels inside,and a few of them(2 cases)underwent gravel-like calcification.Patch-like or nodule-like high signal intensity could be seen in the center of the tumors(3 cases)on MRI T1WI and T2WI,while the peripheral part of the lesions showed iso-signal intensity(equal to muscle).On diffusion weighted imaging(DWI)(b=800 s/mm2),the lesions exhibited restricted diffusion at the peripheral part with significant enhancement,and iso-signal intensity at the central part with none or slight enhancement.Histological classification results revealed that 1 of 6 cases was a benign PEComa and 5 cases were malignant PEComas.The expression rates of Melan-A and SMA were 100.0%and 83.3%,respectively.Conclusions The CT,MRI and pathological manifestations of PEComas in children have some distinct features.PEComas are often an oval-like mass with clear borders and nodular margins in the abdominal and pelvic cavity,and tortuous and thickened blood vessels can be seen in the tumor.The periphery of the tumor is the main region to be enhanced by the contrast agent.Local invasion and distant metastasis can be observed.Most of the tumors are malignant in pathology.Both melanocyte and muscle cell markers can be found in the expression of immunohistochemistry.