Assessment of Proliferative Activity and Angiogenesis in Ameloblastoma: A Comparison Based on Patient Age

Background. Plexiform ameloblastoma is more common in younger patients while and the follicular pattern is more frequently seen in older patients. However, factors implicated in determining the microscopic growth pattern of ameloblastoma are unclear.Methods. A total of 23 cases of ameloblastoma were included in this study and were divided into 2 groups according to age : group A≤15 years (12 cases), and group B≥60 years (11 cases). Each group was assessed for predominant histological pattern (follicular vs. plexiform) and for immunoreactivity with 2 monoclonal antibodies : Ki-67 and CD31. Ki-67 labeling index, intratumor microvessel density (IMVD) and intratumor microvessel area (IMVA) were calculated in each case.Results. The majority of cases in group A exhibited a plexiform pattern, while the follicular pattern predominated among group B. Ki-67 labeling index, IMVD, and IMVA were significantly higher in group A than in group B. When the 2 histological patterns of ameloblastoma were compared, only IMVD and IMVA were statistically higher in plexiform ameloblastoma.Conclusions. Our results suggest that angiogenesis could affect the pattern of tumor growth in ameloblastoma. Both angiogenesis and growth pattern were influenced by patient age.