Histopathologic prognostic factors in neuroblastic tumors: definition of subtypes of ganglioneuroblastoma and an age-linked classification of neuroblastomas.

Histopathologic prognostic factors of 295 pretreatment tumors of a total 641 neuroblastomas and ganglioneuroblastomas were studied with the use of the following proposed tumor classification. The tumors were divided into 2 groups: stroma-poor (235 cases) and stroma-rich (60 cases) according to their organizational pattern (stromal development). The stroma-poor group was classified further into 2 subgroups: favorable stroma-poor (84% survival) and unfavorable stroma-poor (4.5% survival) according to the patient's age at diagnosis, degree of maturation, and nuclear pathology [mitosis-karyorrhexis index (MKI)] of the neuroblastic cells. The stroma-rich group was further classified into 3 subgroups: well differentiated (100% survival), intermixed (92% survival), and nodular (18% survival) on the basis of morphology of the immature element in the tumor tissue without regard to patient's age or quantitative maturation. Favorable stroma-poor and well-differentiated and intermixed stroma-rich groups seem to make good prognosis groups (87% survival), which show gradual progression along a maturational sequence according to the age of the patient. Unfavorable stroma-poor and nodular stroma-rich groups form poor prognosis groups (7% survival) and show morphological evidence of malignant or aggressive behavior, such as inappropriate immaturity for age, higher MKI, and gross nodule formation by immature neuroblasts.