Limitations in the ability of NB84 to detect metastatic neuroblastoma cells in bone marrow

BACKGROUND: The accurate assessment of metastases is an essential component of the staging process for children with neuroblastoma. AIMS: To study the sensitivity of the immunohistochemical marker neuroblastoma 84 (NB84) for the detection of bone marrow infiltrates in children with stage 4 neuroblastoma. METHODS: Primary tumour specimens, bone marrow trephine biopsy specimens and lymph node metastases, taken from children with neuroblastoma that had metastasised to bone marrow, were assessed with a panel of commonly used immunohistochemical markers for neuroblastoma. A comparison was drawn between the sensitivity of the marker NB84 for primary tumours and for bone marrow metastases. RESULTS: NB84 immunolabelled all pre-chemotherapy and post-chemotherapy (n = 24) paired primary tumour specimens, as well as each of a further 20, unpaired, pre-chemotherapy primary tumour specimens. It also labelled all (n = 4) lymph node metastases. Immunolabelling of bone marrow trephine biopsy specimens (21/33) was less sensitive. Of 16 primary tumour specimens with a paired bone marrow trephine biopsy specimen, all immunostained positive, whereas only 62.5% of bone marrow biopsy specimens immunostained positive for NB84. The number of bone marrow biopsy specimens immunostaining for NB84 was significantly lower than the number of paired primary tumour specimens (p = 0.041). CONCLUSIONS: NB84 remains a useful marker for the diagnosis of neuroblastoma in primary tumour specimens, but not for neuroblastoma that has metastasised to bone marrow.