Pulmonary blastoma. A case report

Pulmonary blastoma occurred in a 71-year-old man. Bronchial brushing specimens showed numerous epithelial cells and only a few mesenchymal cell clusters. The epithelial cells were round to oval, more uniform and smaller than ordinary adenocarcinoma cells. The nuclear:cytoplasmic ratio of these cells was increased, with an even chromatin distribution, and nucleoli were inconspicuous. Mesenchymal cell clusters were markedly hypercellular and consisted of small and short spindle-shaped cells with hyperchromatic nuclei. Although it is very difficult to diagnose pulmonary blastoma correctly by cytology, the possibility of pulmonary blastoma should be considered when small, nonsquamous neoplastic cells are observed, particularly in association with small and short spindle-shaped cells reminiscent of mesenchymal origin.