Cytologic features of pulmonary blastoma

Pulmonary blastomas are rare lung neoplasms constituting 0.5% of all lung tumors. This tumor has an aggressive course and needs to be recognized on cytology. A preoperative diagnosis of pulmonary blastoma is difficult to obtain by cytopathologic methods. A diagnosis of biphasic pulmonary blastoma should be considered when there is a dimorphic population of cells on cytology. A 30-year-old male presented with gradually progressing breathlessness and left-sided chest pain for the past one month. Chest radiograph and computed tomography of thorax revealed an anterior mediastinal mass that was subjected to ultrasound-guided fine-needle aspiration cytology. Aspiration cytology showed a highly cellular lesion with a dimorphic population of tumor cells in a necrotic background. The possibility of a non-small cell carcinoma was suggested. Subsequent histopathology revealed the tumor to be a pulmonary blastoma. The importance of recognizing the dimorphic population of cells in cytology is discussed.