BACKGROUND AND OBJECTIVEPleuropulmonary blastoma (PPB) is a rare malignant tumor with unique clinicopathological features. The aim of this study is to investigate the clinicopathological features, the diagnosis and differential diagnosis of pleuropulmonary blastoma.

METHODSFive cases of PPB were analyzed by light microscopy, immunohistochemistry and their clinical data, and the relative literatures were reviewed.

RESULTSFive cases of patients suffered from PPB were aged from 21 to 47 months (mean 32.8 months). Most of the masses were located in the thoracic cavities and 4 cases accompanied with pleural effusions. Histologically, these tumors included 1 case of type I PPB which showed pure cystic architecture; 2 cases were type II PPB which showed cystic and solid masses accompanied with rhabdomyoblastic differentiation and nodules of cartilage; the other 2 cases were type III PPB and characterized by absolute solid masses with anaplastic undifferentiated sarcomatous components. Immunohistochemical studies showed that tumor cells were positive for Vimentin and some for Desmin and Myogenin, the nodules of cartilage were positive for S-100. The tumor cells were negative for PCK, EMA and CD99.

CONCLUSIONPleuropulmonary blastoma is a rare and highly aggressive malignancy arising in the lung and pleural of infancy and early childhood. The type I, II and III PPB have unique clinicopathological features respectively. This kind of tumor should be distinguished from some benign and malignant diseases such as congenital cystic adenomatoid malformation (CCAM) and embryonal rhabdomyosarcoma.