To identify factors associated with skull base involvement (SBI) of maxillary ameloblastomas (MA).

This retrospective cohort study was composed of MA patients treated during a 7-year period. Demographic, radiographic, and nine immunohistopathologic predictor variables were included. The outcome variable was presence of SBI (yes/no). Descriptive, bi- and multivariate statistics were computed, and P ≤ .05 in multivariate analyses was considered statistically significant.

The sample comprised 23 subjects (34.8% females; 21.7% with SBI) with a mean age of 50.3 ± 18.2 years. Candidate predictors of an SBI in MAs were 1) male gender, 2) a low Karnofsky Performance Status score (KPS), 3) multilocular radiolucency, 4) ill-defined margins, 5) cortical perforation, 6) inclusion of an unerupted tooth, 7) moderate to strong reactivity to p53, Ki-67, CD10, astrocyte elevated gene-1 (AEG-1) protein, carbonic anhydrase IX (CA IX), calretinin (calbindin2; CALB2), and BRAF-V600E, and 8) negative to low immunopositivity to α-smooth muscle actin (α-SMA) and syndecan-1 (CD138). However, multivariate analyses confirmed the significant associations of SBI with negative/low syndecan-1 reactivity (P = .003; adjusted odds ratio [OR_adj.], 4.04; 95% confidence interval [95% CI], −.89 to −.48; Pearson's Correlation Coefficient [r] = −.74) and with KPS (P = .003; OR_adj., 4.04; 95% CI, −.78 to −.17; r = −.54) only.

Our findings suggest an aggressive approach to MAs with negative to low syndecan-1 immunopositivity and/or in multi-morbid patients (who may have difficulty in access to health care). Otherwise, health care inequalities due to low KPS scores should be minimized or eliminated.