Diagnostic markers in paediatric medulloblastoma: Paediatric Oncology Group Study

Aims: We have reviewed immunohistochemically 17 paediatric medulloblastomas in order to determine if correlations exist that might be useful in subcla ssifying these tumours. Methods and results: The patient group included 11 children who had died (m ean survival 13 months) and six still alive (followed for up to 10 years). Ten tumours were diffuse and six were nodular (one biopsy had only perivasc ular tumour), Of the 10 diffuse tumours, three were desmoplastic: of the si x nodular tumours. all six were desmoplastic. All 17 tumours were synaptoph ysin-reactive: three nodular tumours were glial fibrillary acidic protein ( GFAP)-reactive in the nodules (two of three S100-reactive tumours were also GFAP-reactive), MIB-1 labelling indices (LI) ranged from 5 to 80%. Six tum ours exhibited at least 1% LI against Tp53 (Mab D07 and/or Mab 1801). Eight cases were 100% bcl2-reactive with nine cases having an LI<80% ('low label ling'). All nine 'low labelling' bc12 cases were TP53 non-reactive: all six Tp53-reactive cases were bcl2 100% reactive. Six of 10 patients with diffu se medulloblastomas survived 18 months or less while four of 10 are alive u p to 10 years. In contrast, five of six patients with nodular neoplasms die d within 48 months of diagnosis with one patient followed up for less than 1 year. Conclusions: Immunohistochemistry is a useful adjunct in characterizing sub sets of paediatric medulloblastomas and confirms that larger co-operative s tudies mag be fruitful in identifying a prognostic utility of a combined hi stochemical/immunohistochemical analysis on these tumours.