腮腺基底细胞腺瘤的MRI诊断与鉴别诊断

MR imaging and differential diagnosis of basal cell adenoma in parotid gland

目的 :分析腮腺基底细胞腺瘤(BCA)的MRI征象,提高术前诊断正确率,减少误诊。方法 :回顾性分析经手术病理证实的33例腮腺BCA的MRI平扫及增强扫描表现。结果:女性多见,平均年龄52岁,临床病程较长,多表现为无痛性肿块。33例34个病灶,25个位于腮腺浅叶,7个位于深叶,2个跨深浅叶;类圆形或椭圆形26个,分叶状或不规则状8个;28个病灶直径≤3 cm,6个>3 cm;2个部分边缘欠清,32个边缘清晰,其中24个可见低信号包膜,7个边缘清晰,但包膜未显示,1个于T_1WI上周围见薄层高信号环;肿块实性部分大部分呈稍等T_1稍长T_2信号。增强扫描21例中(22个病灶),18个呈明显持续强化,4个呈中度持续强化,4个见短T_1长T_2出血及液平,14个见未强化囊变区,其中4个为较大囊,10个为微囊或裂隙状。2个见壁结节。结论:腮腺BCA的MRI表现有一定特征性,结合临床,可提高术前诊断正确率,但确诊依赖病理及免疫组化。

Objective：The purpose of this study was to analyze MR imaging features of basal cell adenoma in parotid gland,so as to improve diagnostic accuracy and to decrease misdiagnosis. Methods：Clinical data and imaging features of 33 cases of basal cell adenoma in parotid gland confirmed by surgery and pathology were retrospectively analyzed,including sex,age,clinical manifestation,location,number,size,shape,margin,pre-and post-contrast MR,as well as intratumoral hemorrhage,cystic change and mural nodule. Results：Our study showed basal cell adenoma in parotid gland occurred more common in women than in man.The average age was about 52. Patient usually had long history of painless mass. There were 34 masses altogether in the 33 cases,25 of which were seen in superficial lobe,7 in deep lobe and 2 in both superficial and deep lobe. 26 masses were oval and the other 8 masses were lobular or irregular in shape. 28 masses were less than 3 cm and the other 6 masses were greater than 3 cm in size. 2 masses had ill-defined margin and the other 32 masses had well-defined margin,24 of which had low signal capsule. Peripheral thin-ring with high signal intensity on T2 WI image was seen in 1 mass. Most of the solid component manifested as iso-intensity on T1 WI and mild hyperintensity on T2 WI. Of all the 21 cases（ 22 masses） which underwent post-contrast MRI study,18 demonstrated significantly persistent enhancement and 4 demonstrated moderate persistent enhancement. Short T1 and long T2 signal was seen in 4 masses with fluid level,representing hemorrhage. Cystic region was seen in 14 masses,4 of which were large,and 10 of which demonstrated micro-cysts or cleavage-like region. Mural nodule was seen in 2masses. Conclusion：Basal cell adenoma in parotid gland has some characteristics on MR imaging. Diagnostic accuracy before surgery may be improved with careful observation of this features and correlating with clinical data. It is confirmed by pathology immunochemistry.