Morphometric study of nucleolar organiser regions in ameloblastoma and basal cell carcinoma.

Ameloblastoma and basal cell carcinoma share histological similarities. Morphometric analysis of nucleolar organiser regions (NORs) from ameloblastoma and basal cell carcinoma (BCC) was carried out by silver (Ag) staining. Mean counts were lower in ameloblastoma (1.652 +/- 0.032) compared to those in BCC (2.354 +/- 0.054). Ameloblastoma presented one or two NORs per nucleus, in a narrow distribution (one to four NORs per nucleus). In contrast, BCC exhibited two or three NORs per nucleus, in a broad distribution (one to six NORs per nucleus). Perimeter and area measurements of AgNOR dots yielded significantly higher mean values for ameloblastoma. Our data suggest that most BCC cells are in mitosis, showing small and numerous NORs in each nucleus, while ameloblastoma cells are in interphase, showing one or two large NORs in each nucleus. Although ameloblastoma and BCC are neoplasms with similar growth patterns, they have cell populations with statistically significant differences in AgNOR patterns.