We now demonstrate that [Beta]III is a potential marker of high-grade astrocytomas, and its expression may also define incipient anaplastic phenotypes in diffuse fibrillary astrocytomas.
The cases were grouped into high-grade astrocytomas (consisting of anaplastic astrocytoma, WHO grade 3, and glioblastoma multiforme, WHO grade 4); diffuse fibrillary astrocytomas (including gemistocytic astrocytomas, WHO grade 2); and pilocytic astrocytomas (WHO grade 1).
In diffuse fibrillary astrocytomas, the distribution of [Beta]III immunoreactivity was also substantially less than that in high-grade astrocytomas (MLI, 4%; IQR, 0.2%-21%) (P [is less than] .0001) (Figure 1).
The Ki-67 MLI for high-grade astrocytomas, WHO grades 3 and 4 combined, was 24% (IQR, 17%-25%) (P [is less than] .002 vs diffuse fibrillary astrocytomas; P [is less than] .0001 vs pilocytic astrocytomas).
When the tumor grade is taken into consideration, 7 (13.2%) cases were pilocytic astrocytomas (WHO grade I), 22 (43.1%) cases were fibrillary astrocytomas
(WHO grade II), 6 (11.8%) cases were anaplastic astrocytomas (WHO grade III) and 16 (31.4%) cases were glioblastomas (WHO grade IV).