摘要目的：探讨胸膜肺母细胞瘤的临床病理特点、组织起源及预后。方法对16例胸膜肺母细胞瘤患儿（年龄1畅7～5畅3岁，平均年龄3岁）肿瘤标本，用HE、免疫组织化学（ EnVision法）染色及电镜技术进行观察。结果16例患儿中，Ⅰ、Ⅱ、Ⅲ型分别为2、7及7例。Ⅰ型囊性型，为被覆呼吸道上皮的薄纤维囊壁，上皮下可见原始间叶或原始胚芽，伴或不伴肌母细胞分化及软骨成分；Ⅱ型囊实相间型，囊壁内成分较Ⅰ型还出现了间变肿瘤细胞；Ⅱ型实性区和Ⅲ型实性型肿瘤成分镜下呈原始胚芽、梭形原始间叶肿瘤细胞和不同肉瘤成分的混合；Ⅱ型及Ⅲ型肿瘤内常见间变瘤细胞及细胞内外嗜酸性小体。3型胸膜肺母细胞瘤中的上皮成分均为良性。免疫组织化学化标记仅显示肿物中原始间叶细胞的分化方向。16例均表达波形蛋白，骨骼肌分化呈结蛋白、Myogenin、平滑肌肌动蛋白阳性表达，软骨分化呈S-100阳性表达，纤维组织细胞分化呈CD68表达，余突触素、CD99、CD117均阴性，良性上皮成分呈AE1／AE3及上皮细胞膜抗原阳性表达。电镜下12例均可见细胞器稀少的原始间叶细胞及核异染色质丰富的间叶细胞，后者部分胞质内见发育不良的肌丝。9例随访5～48个月，4例死亡。结论胸膜肺母细胞瘤好发于6岁以下的儿童，具有特殊的病理形态，可能起源于胸腔脏层胸膜或胚体中胚层的多潜能干细胞，为预后差的儿童罕见肺肿瘤。

abstractsObjective To study the clinicopathological and immunohistochemical features , histogenesis and prognosis of pleuropulmonary blastoma ( PPB) in children.Methods PPB specimens from 16 pediatric cases with an age ranging from 1 year and 7 months to 5 years and 3 months ( mean age of 3 years) were retrieved and analyzed by routine histological , immunohistochemical and electron methods.Results Among 16 patients, there were 2 type Ⅰ, 7 type Ⅱ and 7 type Ⅲ PPB cases.Type Ⅰ PPB as multilocular cystic structure , consisted of thin fibrous wall lining the respiratory epithelium , subepithelial primitive blastema or immature mesenchymal cells , with or without rhabdomyoblastic differentiation or cartilage;Type Ⅱ PPB as cystic-solid tumor,comparing with type Ⅰ, consisted of intracystic components with appearance of anaplastic tumor cells.TypeⅢPPB consisted of completely solid mass , the same as the solid region of type Ⅱ, had mixed pattern including blastema ,undifferentiated spindle-cell proliferations and sarcomas.In addition, anaplastic tumor cells and intra-and extra-cytoplasmic eosinophilic globules were also commonly present.Epithelial components in PPB were benign.Immunohistochemical study showed primitive mesenchymal differentiation of tumors.All cases were positive for vimentin , desmin, myogenin and SMA in tumors with skeletal muscle differentiation , S-100 was positive in tumors with cartilage differentiation.All tumors were negative for synaptophysin ,CD99,and CD117.Benign epithelial components were positive for AE1/AE3 and EMA.In 12 cases, electron microscopy revealed few organelles in the primitive mesenchymal cells and rich heterochromatin in mesenchymal cells , the latter also demonstrating cytoplasmic myofilament dysplasia.Nine cases had clinical follow-up ranging from 5 to 48 months, of which 4 patients died.Conclusions PPB is a rare lung neoplasm of children under the age of 6 years,with distinct pathological morphology .PPB may arise from lung or pleura mesenchymal cells and has a poor clinical outcome.