Differences in MYB expression and gene abnormalities further confirm that salivary cribriform basal cell tumors and adenoid cystic carcinoma are two distinct tumor entities.

BACKGROUND

In practices, some cases of salivary basal cell tumors that consist mainly of cribriform growth pattern are difficult to differentiate from adenoid cystic carcinoma (AdCC). Identification of reliable molecular biomarkers for the differential diagnosis between them is required.

METHODS

Twenty-two cases of cribriform salivary basal cell tumors (at least 10% cribriform pattern present in each tumor) comprising 18 cases of basal cell adenoma (BCA) and four cases of basal cell adenocarcinoma (BcAC) were collected between 1985 and 2008. Twenty cases of cribriform AdCC were retrieved from our archives. MYB protein expression and gene abnormalities were detected in all cases by immunohistochemistry (IHC) and fluorescent in situ hybridization (FISH) analyses, respectively.

RESULTS

Neither MYB protein nor split genes were detected in any of the cases of cribriform basal cell tumors, while 55% (11/20) of cases of cribriform AdCC had MYB protein expression. High MYB expression was detected in 81.8% (9/11) cases, while low expression was found in the remaining cases. FISH analysis indicated that nine AdCC tumors with high MYB protein expression were split gene-positive, while MYB gene splitting was not detected in the 11 cases with low or absent MYB protein expression.

CONCLUSION

The molecular changes in AdCC differ from those associated with cribriform basal cell tumors, which further confirms that cribriform basal cell tumors and AdCC are two distinct tumor entities. Simultaneous detection of MYB protein expression and the associated molecular changes could be beneficial in differentiating salivary cribriform basal cell tumors from AdCC.