Imaging of the unusual pediatric 'blastomas'.

'Blastomas' are tumors virtually unique to childhood. Controversy surrounds their nomenclature and there is no globally accepted classification. They are thought to arise from immature, primitive tissues that present persistent embryonal elements on histology, affect a younger pediatric population and are usually malignant. The 'commoner' blastomas (neuroblastoma, nephroblastoma, hepatoblastoma, medulloblastoma) account for approximately 25% of solid tumors in the pediatric age range. We present examples of the more unusual blastematous pediatric tumors (lipoblastoma, osteoblastoma, chondroblastoma, hemangioblastoma, gonadoblastoma, sialoblastoma, pleuropulmonary blastoma, pancreatoblastoma, pineoblastoma, and medullomyoblastoma) that were recorded in our institution. Although these rare types of blastomas individually account for <1% of pediatric malignancies, collectively they may be responsible for up to 5% of pediatric tumors in a given population of young children. Imaging is often non-specific but plays an important role in their identification, management and follow-up. Some characteristic imaging features at diagnosis, encountered in cases diagnosed and treated in our institution, are described and reviewed.