Evaluation of SOX2 as a potential marker for ameloblastic carcinoma

Objective Ameloblastic carcinoma often poses diagnostic challenges in its separation from benign ameloblastoma with atypical cytologic features or an unusual clinical course. This study aimed to determine whether SOX2 (sex determining region-Y-related high mobility group box 2), a protein expressed in the epithelial basal proliferative zone in dentigerous cysts, is a marker for ameloblastic carcinoma as well as for high-grade transformation in ameloblastic neoplasms. Study Design Immunoperoxidase stains were performed according to a standard protocol. Immunostains were interpreted independently by 3 pathologists, and scores were recorded based on the percentage of staining and intensity of staining in the cells of interest. Results The diffuse strong nuclear staining pattern has 86.4% specificity (19 of 22) to indicate the presence of high-grade features and has 76.9% sensitivity (10 of 13) in comparison with benign counterparts ( P  = .0021). Although previously shown as a marker for ameloblastic neoplasms, calretinin is weakly positive in a few cells in 50% (5 of 10) of ameloblastic carcinoma and 43% (3 of 7) of benign ameloblastic neoplasms, with little value in highlighting the high-grade change ( P  = .36). Conclusions The diffuse nuclear staining pattern of SOX2 is suggestive of a high-grade process in ameloblastic neoplasms. Numerous aggregates of cells harboring dense nuclear stain should raise concern for a malignancy.