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Pineoblastomas occur in RB-1 mutation carriers,1 but are rarely seen in association with other hereditary syndromes.2 Germline DICER1 mutations are associated with embryonal tumours such as pleuropulmonary blastoma (PPB),3 ,4 so we hypothesised that such mutations might also occur in children with pineoblastoma. Here we describe a novel deleterious germline DICER1 mutation in a young child with a highly aggressive pineoblastoma. In addition, we observed loss of heterozygosity (LOH) of the wild-type allele, an event not previously reported in DICER1 associated tumours.5 ,6 Our observations suggest: (1) pineoblastomas are associated with germline DICER1 mutations; and (2) unexpectedly, tumour cells can thrive in the absence of functional DICER1.
The pineal gland, so named by Galen because of its resemblance to a pine nut, is a ∼175 mg midline structure situated on the posterior wall of the third ventricle, deep between the cerebral hemispheres. Pineal gland tumours are often derived from ectopic germ cell tissue, but pineocytomas and pineoblastomas also occur. A pineoblastoma is a supratentorial primitive neuroectodermal tumour arising in the pineal gland. Germline mutations in tumour suppressor genes have rarely been associated with pineoblastomas,1 ,2 but mutations in RB-1 can result in so-called ‘trilateral retinoblastoma’.1
We obtained …