Proliferation indices of vestibular schwannomas by Ki-67 and proliferating cell nuclear antigen.

Two immunohistologic demonstrations of markers of proliferating cells, Ki-67 and proliferating cell nuclear antigen, were applied to tissues from 10 vestibular schwannomas. Each method demonstrated three distinct rates of positively stained cells (p < .01 and p < .015, respectively, for each method). There was a one-to-one correspondence between the two immunohistologic methods in the assignment of cases to each growth rate category except for two cases (Spearman rank correlation r = 0.76, p < .05). These data support the concept of distinct growth rates in vestibular schwannoma. Tissues were also sampled from different areas of the same tumor within nine samples. The results suggest that tumor growth is not homogeneous within a tumor, but that proliferation may be more active near the surface.