Cyopathologic and histologic features of biphasic pulmonary blastoma: a case report

Biphasic pulmonary blastoma is a rare malignant neoplasm of debatable histogenesis. Although well described histologically, it is scarcely mentioned in the cytologic literature.

A 78-year-old man reporting intermittent hemoptysis was admitted to the hospital. Chest radiography revealed a right-sided pulmonary mass. Cytologic examination of tumor specimens revealed 2 types of malignant cells. The smears were highly cellular, with a necrotic background. The stromal cells had predominantly round to ovoid or spindle-shaped nuclei and scant cytoplasm, and the nucleoli had slightly irregular borders with coarsely aggregated chromatin. The epithelial cells were arranged in sheets and glandular configurations. The cytoplasm of these cells was finely vacuolated or foamy, with indistinct cellular boundaries; eccentrically located nuclei were hyperchromatic and had irregularly shaped nucleoli. The cell block preparation showed a distinctly biphasic malignant tumor with the classic morphologic features of pulmonary blastoma.

A preoperative diagnosis ofpulmonary blastoma is difficult to obtain by cytopathologic methods. A diagnosis of biphasic pulmonary blastoma should be considered whenever epithelial cells and a separate population of stromal cells are seen in a pulmonary exfoliative cytology specimen.