Biphasic Tumors of the Lungs
Biphasic tumors are a group of tumors that are composed of two elements: malignant epithelial and mesenchymal components. These tumors only rarely arise in the lungs and overall represent less than 2 % of all primary lung neoplasms. In the bronchopulmonar
- PDF / 5,766,523 Bytes
- 22 Pages / 595.28 x 790.87 pts Page_size
- 51 Downloads / 189 Views
Biphasic Tumors of the Lungs
Introduction Biphasic tumors are a group of tumors that are composed of two elements: malignant epithelial and mesenchymal components. These tumors only rarely arise in the lungs and overall represent less than 2 % of all primary lung neoplasms. In the bronchopulmonary system, the tumors belonging to this group include pulmonary blastoma, pleuropulmonary blastoma, and carcinosarcoma. Pulmonary blastomas and carcinosarcomas in particular have caused great contention in the literature with regard to their histogenesis, nomenclature, and classification; and to date no universally accepted concept exists as to whether these tumors represent independent clinicopathological entities or rather constitute subtypes of other neoplasms. However, based on their distinct morphological features and the results of the latest molecular investigations indicating tumor autonomy, these neoplasms warrant inclusion as independent entities. The pertinent characteristics of the three neoplasms are summarized in Table 5.1.
Pulmonary Blastoma History, Histopathogenesis, and Definition Pulmonary blastomas are biphasic tumors composed of mixed epithelial and mesenchymal elements in which both components have the appearance of embryonal structures. Pulmonary blastoma was first described by Barnard in 1952 [1] reporting on a peculiar lung tumor with the features of mixed carcinomatous and sarcomatous elements resembling the developing lung of an embryo. He termed this tumor “embryoma of the lung.” Three more of these
cases were studied by Spencer in 1961 [2] who coined the term “pulmonary blastoma” because of their morphologic similarity to nephroblastomas of the kidney. He proposed that both epithelium and stroma derived from primitive mesenchymal tissue similar to the development of nephroblastoma in the kidney. This view was disputed in subsequent reports that, based on morphological and ultrastructural investigations, suggested that the epithelial and mesenchymal elements were distinct enough to warrant classification as a form of carcinosarcoma [3–6]. More recent immunohistochemical and molecular investigations have demonstrated similar antigen expression and gene mutations in both elements of pulmonary blastoma and confirmed that this tumor very likely is derived from a totipotential stem cell and should therefore be regarded as a distinct clinicopathological entity [7–13]. A monophasic variant of pulmonary blastoma was described by Kradin in 1982 [14] who reported a lung tumor resembling pulmonary blastoma but without the sarcomatous element, the so-called pulmonary endodermal tumor resembling fetal lung. Similar tumors were subsequently referred to as “well differentiated adenocarcinoma simulating fetal lung tubules” and “adenocarcinoma of the fetal lung type” [15–17]. It soon emerged that this monophasic type of pulmonary blastoma, although histogenetically apparently linked to the biphasic type, is more prevalent in women and has a better prognosis compared to the biphasic tumor [10, 12, 14–17]. For thi
Data Loading...
