Mesenchymal neoplasia and congenital pulmonary cysts

A malignant mesenchymoma exhibiting a varied spectrum of differentiation developed within a congenital pulmonary cyst 6 1/2 years after the cyst was first recognized. Related tumors with a similar gross appearance have been previously described and have included rhabdomyosarcomas and so-called pulmonary blastomas. There is a low but distinct risk for the development of mesenchymal sarcomas within congenital peripheral pulmonary cysts.