Posterior Fossa Group A Ependymoma in Trisomy 21.

Brain tumors are the most common solid tumors in children. However, the risk of central nervous system tumors appears reduced in individuals with trisomy 21, particularly for tumors of nervous tissue. We present the first reported case of posterior fossa group A (PFA) ependymoma in a patient with trisomy 21. Including this case, only four cases of ependymoma in trisomy 21 have been reported. Similar to medulloblastoma, ependymoma may occur at a markedly reduced frequency in trisomy 21. Investigating the protective role of trisomy 21 in ependymoma development may provide new insights into its pathophysiology and management.