Pulmonary blastoma. A light and electron microscopic study

A case of pulmonary blastoma studied with the electron microscope showed two distinct cell types, i.e., epithelial and mesenchymal elements. The former demonstrates the differentiation toward ciliated bronchial cells, and the latter, cartilage. In view of these findings, coupled with the current understanding of pulmonary morphogenesis, the pulmonary blastoma is more likely to be a carcinosarcoma than a true blastoma. However, the separation between pulmonary blastoma as usually employed and the so‐called pulmonary carcinosarcoma seems to be desirable because of different clinicopathologic features.