Pediatric atypical neuroblastoma: three cases report and a literature review

Atypical neuroblastoma (NB) refers to the primary onset of NB without a detectable mass in common sites, but in bone marrow or/and other metastasis parts. For a better elucidation and defining atypical NB, our experiences in three unusual cases of Chinese atypical NB are reported on this paper. Clinically, the first case had no other parts of the tumor infiltration in addition to bone marrow, but the second and third case was presented with the metastasis sites of NB including both bone marrow and bone. Usually in China, treatments of radiotherapy, surgery and hematopoietic stem cell transplantation (HSCT) may not suitable for patients with atypical NB, likely due to the absent of visible solid mass and sometimes without the drug approval of the conditioning regimen like melphalan, so, aggressive chemotherapy seems to be the effective first-line choice. Our experiences show that atypical NB might be associated with a worse outcome than typical NB despite extremely aggressive treatments. Several important aspects of diagnosis and management of atypical NB are highlighted in the following three case reports.