Prognostic subgroups for undifferentiated neuroblastoma: immunohistochemical study with anti-S-100 protein antibody.

Pathologic prognostic factors in 36 undifferentiated neuroblastomas were studied by an immunohistochemical staining technique with anti-S-100 protein antibody. Nuclear abnormalities of neuroblastic cells (mitosis and karyorrhexis/5,000 cells [MKI]), the incidence of S-100 protein-positive cells in the supportive stroma, and the age of the patients at diagnosis were analyzed both individually and in combination. Based on the evaluation of these factors, two prognostic subgroups were identified for these tumors. Tumors for which the prognosis was good (all nine patients alive) occurred in younger patients (younger than 1.5 years), showed low (less than 100) or intermediate (100 to 200) MKI, and had positive to intensely positive staining for S-100 protein. Cases in which the prognosis was poor (7 per cent survival) had single or multiple factors of high (greater than 200) MKI and/or absent or weak staining for S-100 protein and/or older age (older than 1.5 years) at diagnosis. These results were compared with other clinical information.