Regrowth of an infantile neuroblastoma with two distinct DNA hyperdiploid peaks during spontaneous regression

Abstract

Infantile neuroblastoma is a curable disease characterized by frequent spontaneous regression, and a localized neuroblastoma in an infant is sometimes carefully observed with a “wait and see” strategy. We present the case of an infant with a localized neuroblastoma in which two distinct clones were cytogenetically determined. The infant was male and diagnosed as having a localized cystic neuroblastoma of the right adrenal gland. During a follow-up period with careful monitoring, the tumor once regressed, but later showed progression with a growing solid mass after 6 months. The tumor was finally resected when he was 11 months old. Interestingly, DNA ploidy analysis revealed 2 different hyperdiploid peaks within a single tumor, suggesting heterogeneity. This hypothesis was supported by histopathological findings: both well-differentiated and poorly differentiated segments were observed in the resected tumor. It should be noted that even low-grade neuroblastoma may have tumor heterogeneity.