INCREASED NUMBERS OF ARGYROPHILIC NUCLEOLAR ORGANIZER REGIONS BETWEENPRIMARY AND METASTATIC SITES PREDICT TUMOR PROGRESSION IN STAGE-IV AND STAGE-IV-S NEUROBLASTOMA

Background. A silver colloid technique to determine nucleolar organize r region (AgNOR) number was used to study the proliferative activity o f Stage IV-S neuroblastoma in which a spontaneous tumor regression is often observed. Methods. Primary regional lymph nodes and hepatic lesi ons from five children with Stage IV-S and five with Stage IV neurobla stoma were examined. Results. Average AgNOR counts per tumor cell nucl eus from all five children with Stage IV neuroblastoma were lowest in the primary lesions, intermediate in the metastatic regional lymph nod es, and highest in the distant metastases. However, in four Stage IV-S patients whose metastases later disappeared and showed no sign of rec urrence, the average AgNOR number was similar in primary tumors and me tastatic lesions. In the other patient with progressive metastases ini tially diagnosed as Stage IV-S, the data showed the same pattern as in Stage IV neuroblastoma. Conclusions. The unique AgNOR staining patter n may reflect the proliferative activity of Stage IV-S neuroblastoma. This method may provide further information to differentiate a subtype of metastatic neuroblastoma showing spontaneous tumor regression and/ or favorable prognosis.