Germ-line mutations in the micro-ribonucleic acid processing gene DICER1 have been shown to predispose to a subset of benign tumors susceptible to malignant transformation, including ovarian Sertoli-Leydig cell tumor, nontoxic multinodular goiter, multilocular cystic nephroma and pleuropulmonary blastoma, which can occur in children and young adults. The gene discussed is DICER1; the disease is pleuropulmonary blastoma.