1例成人胸膜肺母细胞瘤的临床病理分析并文献复习

An clinicopathological analysis and literature review of pleuropulmonary blastoma in an adult

目的探讨成人胸膜肺母细胞瘤(PPB)的临床病理特征、诊断及鉴别诊断。方法通过光镜观察、免疫组化研究及分子病理学检测,报道1例成人PPB并复习相关文献。结果患者女,45岁,以"咳嗽及呼吸困难"收住。CT显示左下肺实性肿块。大体检查肿瘤大部分为实性,部分区域可见裂隙及微囊,边界清楚。镜下肿瘤由片层状的恶性原始小细胞及束状胚胎性横纹肌肉瘤样细胞组成,部分间质玻璃样变性。肿瘤细胞具有混合性母细胞样或肉瘤样特征:分化差的细胞呈胖梭形,胞质界限不清,淡嗜酸性,核分裂象多见。免疫组化显示肿瘤细胞vimentin、MyoD-1表达阳性,而上皮性标记物阴性。经高分辨率熔解曲线分析法检测K-RAS基因3号外显子有突变。结论成人PPB是一种罕见的独具病理特征的恶性肿瘤,应注意与其他小细胞或梭形细胞肿瘤的鉴别。

Objective To explore the clinicopathological features,diagnosis and differential diagnosis of pleuropulmonary blasto- ma（PPB）. Methods A case of PPB was reported by light microscopic observation,immunohistochemistry and molecular pathology study with review of related literature. Results A 45-year-old female was admitted to the hospital because of cough and dyspnea. Chest radiogram revealed a solid mass in the left lung. Grossly,the tumor was described as a firm lesion with lumina or multicystic components and well-circumscribed margins. Microscopically, the tumor was composed of sheets of malignant primitive small ceils and fascicles of embryonal rhabdomyosarcoma-like cells with foci hyalinized stroma. Beneath the benign epithelium, the primitive mesenchymal cells showed as mixed blastematous and sarcomatous characteristics that plump spindle shaped cells presented poor differention with abundant eosinophilic cytoplasms and brisk mitotic activities. Immunohistochemically, vimentin and MyoD-1 were positive in malignant small cells but some epithelial markers are negative. Meanwhile, K-RAS extron 3 mutation was detected by high resolution melting analysis（HRMA）. Conclusion Pleuropulmonary blastoma（PPB） is a rare malignant tumor with unique clinicopathological features. It should be distinguished from some mimics such as pulmonary blastoma and embryonal rhabdomyo- sarcoma.