Almost all cases of pleuropulmonary blastoma (PPB), the most common lung malignancy in childhood, are related to biallelic pathogenic variants in DICER1, a gene encoding an RNase III involved in the biogenesis of micro-RNAs, organogenesis and tumor suppression.1 2 Over 70% of patients with PPB are affected by the pleiotropic DICER1-related tumour susceptibility syndrome caused by heterozygous germline DICER1 loss-of-function variants. After a second somatic DICER1 missense mutation has occurred, these individuals may develop PPB, other tumours and non-neoplastic conditions in the thyroid gland, genitourinary system, and several other extrapulmonary sites.