[Clinicopathology and immunohistochemistry of adult type pulmonary blastoma]

To study the clinicopathologic and immunohistochemical features of adult type pulmonary blastoma (PB).

Four cases of adult type PB were studied with light microscopy and immunohistochemical staining.

Three cases of PB were biphasic type and were composed of primitive epithelial component and primitive stromal component; one case of PB was epithelial type and was shown as branching glands with clustered and well-differentiated structure. Immunohistochemical studies showed that AE1/AE3 was positive in the epithelial component in four cases, Vimentin was positive in the stromal component in three cases, thyroid transricption factor-1 was positive in two cases, CD117 was positive in one case, Ki-67 was 2% positive in one case, while P53 was negative in all cases.

The adult type PB is a rarely seen biphasic tumor. It contains a primitive epithelial component and a primitive mesenchymal stroma, which looks like well-differentiated fetal adenocarcinoma. As highly invasive intrathoracic neoplasm, it is mainly found in adult with an unfavorable outcome.