Prognostic Factors : Mitotic-Karyorrhectic Index

Mitotic-Karyorrhectic Index (MKI) in 5000 tumor cells is correlated with prognosis. MKI may be low (<2% or <100 mitotic and karyorrhectic cells per 5000 neuroblasts), intermediate (2% to 4% or 100 to 200 mitotic and karyorrhectic cells per 5000 neuroblasts), or high (>4% or >200 mitotic and karyorrhectic cells per 5000 neuroblasts). High MKI is correlated with amplification of MYCN oncogene (chromosome 2p24) - which is an independent adverse prognostic factor seen in about 25% of neuroblastomas. Cells undergoing karyorrhexis - a process of individual cell death due to genomic instability - have condensed and fragmented nuclear chromatin and dense eosinophilic cytoplasm. The image shows neuroblastoma, undifferentiated subtype, with a high MKI (about 15%).