About Neuroblastoma What is neuroblastoma? How is it diagnosed? Neuroblastoma may be difficult to diagnose as symptoms often do not become apparent until the tumour has reached a certain size. Even then symptoms may be subtle and similar to other more common non-serious childhood diseases. As a result it often takes some time before the final diagnosis of neuroblastoma is made. Often parents wonder if they or a doctor should have noticed something sooner, but because it is such a rare disease it is unlikely that a family doctor will ever see a child with neuroblastoma in a lifetime of practice.