[Pleuropulmonary blastoma: a clinicopathological analysis]

Abstract

Background and objective: Pleuropulmonary 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.

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

Results: Five 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.

Conclusion: Pleuropulmonary 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.

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PPB的病理组织学图像。A：Ⅰ型PPB，肿瘤组织呈囊性（HE, ×40）；B：上皮下似葡萄状肉瘤生发层的原始间叶细胞（HE, ×100）；C：示陷入的良性上皮成分（HE, ×100）；D：示软骨样结节分化（HE, ×40）；E：示间变性未分化肉瘤组织像（HE, ×400）；F：肿瘤细胞示Vimentin阳性（SP, ×200）；G：部分肿瘤细胞示Desmin阳性（SP, ×200）；H：部分肿瘤细胞示Myogenin阳性（SP, ×100） Pathohistologic pattern of PPB. A: Type Ⅰ PPB appears as cystic structure (HE, ×40); B: Primitive mesenchymal cells like cambium layer of botryoid sarcoma dispersed beneath the epithelium (HE, ×100); C: Benign epithelium entrapped within the tumor (HE, ×100); D: Nodules of cartilage in the tumor (HE, ×40); E: Histologic pattern like anaplastic undifferentiated sarcoma (HE, ×400); F: Tumor cells positive for Vimentin (SP, ×200); G: Partial tumor cells positive for Desmin (SP, ×200); H: Partial tumor cells positive for Myogenin (SP, ×100)