The existence of biphasic neoplasms occurring primarily in the lung is a well-known albeit rare event. The spectrum of malignant tumors displaying a mixed epithelial/mesenchymal growth pattern is rather narrow when these tumors occur primarily in the lung. The two most often encountered neoplasms showing features of epithelial and mesenchymal differentiation are carcinosarcomas and pulmonary blastomas. Tumors with analogous features are of ubiquitous distribution in the human body and have been described in numerous other organs, including the gastrointestinal tract, the genitourinary tract, and the endocrine system. Although the histopathologic features of these tumors may seem simple in most cases, there appear to be numerous pitfalls in their diagnosis; gray areas still remain in the characterization of these tumors, because a certain degree of overlap may be encountered with these two conditions. Such problems are understandable because the incidence of these tumors in the general population is very rare. Therefore, one is expected to find divergent points of view regarding these neoplasms. It is of importance, however, to unify criteria not only for diagnostic purposes, but also to determine the prevalence and behavior of these neoplasms, because such information may provide a rationale for adjustment and improvement in the treatment and diagnosis of these unusual neoplasms. We will review past and current concepts regarding these unusual tumors, as well as their more salient histopathologic features.

The clinical analysis and review of literature of pulmonary carcinosarcoma and blastoma.Zhonghua Jie He He Hu Xi Za Zhi. 1999 Sep;22(9):541-4

OBJECTIVE: To explore the clinical characteristics, diagnosis, treatment of pulmonary carcinosarcoma and blastoma. METHODS: Summarizing retrospectively 15 cases of pulmonary carcinosarcoma and 2 cases of pulmonary blastoma from January 1979 to November 1998, and reviewing literature to analyse their histologic, clinical feature, diagnosis and treatment. RESULTS: Pulmonary carcinosarcoma and blastoma both were found to be rare malignant tumors, and both epithelial and mesenchymal elements can be seen under the microscopy with different characteristic features. It was hard to be diagnosed before operation. The main symptoms of pulmonary carcinosarcoma were cough, expectoration, sometimes bloody phlegm. X-ray showed that peripheral type were most common, and 2-5 cm in size, well-distributed in density, some showed central or eccentric cavities whose wall was irregular. The margin of the focuses were clear, leafy, the distensive lymph nodes of hilum or mediastium could also be seen. Bronchoscopic examination revealed the bronchial cavity was obstructed by mass or became stricted. Local biopsy can found squamous, adenocarcinoma or large cell carcinoma, respectively. Malignant cell can also be found in sputum. So it was easy to be confused with lung cancer. 14 cases of the carcinosarcoma were treated surgically and diagnosed, 1 case was diagnosed by lymph node biopsy. The symptoms of pulmonary blastoma were fever and hemoptysis. X-ray or CT scan showed an isolated mass in the lung, with uneven density. Malignant cells in pleural effusion were found in one case and can not be diagnosed definetely but by pulmonary puncture. The another case was diagnosed by surgical operation. 15 cases of this group were followed up, in which 4 cases are still alive (including 1 case of pulmonary blastoma), the 1-year survival of carcinosarcoma is 30% (3/10), 2-year survival 20% (2/10), in which 1 case survived more than 6 years. Another pulmonary blastoma case only survived 3 months. CONCLUSIONS: These 2 kinds of malignant tumor are often easy to be misdiagnosed, and prognosis is very poor. Surgical resection is the main method of diagnosis and treatment.