OBJECTIVE: We performed an immunohistochemical study in a series of ameloblastomas with different histology to explore the existence of a correlation between CD10 immunoreactivity in peritumoral stromal cells and the type of ameloblastoma with a high risk of local recurrence. STUDY DESIGN: A total of 45 ameloblastomas (18 unicystic [UA], 4 peripheral [PA], 23 solid/multicystic [SA]) were evaluated. Cases showing immunoreactivity for CD10 in < and > or =10% of stromal cells around tumoral epithelial islands, were considered, respectively, negative and positive. Correlations between stromal CD10 expression and histopathologic types with low and high risk of recurrence were evaluated by statistical analysis. RESULTS: SA cases showed a significantly higher percentage of stromal CD10-positive cells than the UA and PA variants. A strong intensity of immunostaining was observed only in SA. CONCLUSIONS: Our results suggest that CD10 expression might be associated with stromal invasion in ameloblastoma variants with a high risk of recurrences.