Immunohistochemical expression of K6, K8, K16, K17, K19, maspin, syndecan-1 (CD138), alpha-SMA, and Ki-67 in ameloblastoma and ameloblastic carcinoma: diagnostic and prognostic correlations.

OBJECTIVE: To identify cutoff values of markers that correlate with the histopathologic diagnosis of ameloblastic carcinoma (AC) and/or the increased recurrence potential of ameloblastoma (AB). STUDY DESIGN: Immunohistochemical expression (IHCE) of 9 selected markers were investigated in 18 non-recurrent ameloblastomas (NRABs), 6 recurrent ameloblastomas (RABs), and 5 ACs. RESULTS: No significant difference in IHCE of K6, K8, K16, K17, K18, K19, maspin, or syndecan-1 was observed among study groups. alpha Smooth muscle actin (alpha-SMA)-positive area in central epithelial cells significantly differentiated between AB and AC (P = .017; t -test). Ki-67 score significantly differentiated between AB and AC (P < .005; t -test) and between AC and RAB (P = .015; ANOVA/post hoc). CONCLUSIONS: Ki-67 score of 75 cells/HPF (ROC curve) is a potential indicator of AC. Clinical recurrence of AB may be predicted by alpha-SMA expression pattern. Syndecan-1 and alpha-SMA may indicate a higher aggressive potential of AB when expressed in the stroma.