The average age of diagnosis is 35 to 40 years, and a large case series reported an equal sex distribution. Eighty percent of patients with pulmonary blastoma are smokers, and 40% may be asymptomatic. Radiologically, the tumor usually appears as a solitary, well-defined peripheral nodule or mass, with upper-lobe predominance. Histologically, pulmonary blastoma can be divided into monophasic (well-differentiated adenocarcinoma) and biphasic types. Both types consist of neoplastic glands with branching tubules lined by stratified columnar cells and clear cytoplasm with little nuclear hyperchromasia. In addition, biphasic blastoma has sarcomatous or embryonic mesenchymal components. A case series described important characteristics of pulmonary blastoma that differentiate it into two types. Well-differentiated fetal adenocarcinomas are usually smaller tumors (< 5 cm), and patients are more likely to be asymptomatic. Fourteen percent of patients with well-differentiated fetal adenocarcinomas died, and a poor prognosis was associated with thoracic adenopathy, initial metastases, and tumor recurrence. Biphasic tumors were more likely to be associated with pleural effusions and upper-lobe predominance. Fifty-two percent of patients with biphasic blastoma died, and indicators of poor prognosis included first tumor recurrence followed by initial metastases and then tumor size.