A rare case of presacral cystic neuroblastoma in an infant.

Cystic neuroblastoma (CN) is an extremely rare entity, although neuroblastoma is the most common solid tumor in infants. The radiologic diagnosis of CN is very difficult because of both the rarity and minimum solid component of the lesion. We describe herein the case of a 2-month-old girl presenting with dysuria because of a large presacral mass. Imaging studies including ultrasonography, computed tomography, and magnetic resonance imaging demonstrated a large septated cystic tumor mimicking a cystic sacrococcygeal teratoma, which commonly occurs in the presacral region. The tumor was finally diagnosed as CN after surgical resection. This is the second case report of presacral CN in the English literature. Cystic neuroblastoma should be considered in the differential diagnosis of presacral cystic tumors in infants.