The cytomorphology of pleuropulmonary blastoma.

Pleuropulmonary blastoma is a rare, primitive primary neoplasm of the thorax in young children. The tumor, which is often but not always associated with cystic lung lesions, may arise in pulmonary parenchyma, the mediastinum, and pleura. Histologically, it is characterized by a biphasic neoplastic population of undifferentiated-appearing small round cells and larger spindle-shaped cells. A proportion of these cancers may also manifest more specific mesenchymal differentiation. In contrast to the pulmonary blastoma of adults, a malignant epithelial component does not occur. We present herein the third known case of a fine needle aspiration biopsy of a pleuropulmonary blastoma in a 5-year-old girl. The smears were moderately cellular and included an admixture of the characteristic small ovoid blastemal elements and scattered spindled mesenchymal tumor cells.