Diagnostic role of DOG1 and p63 immunohistochemistry in salivary gland carcinomas.

BACKGROUND The differential diagnosis of salivary carcinomas is always difficult and challenging. Salivary neoplasms often shows more than one growth pattern and significant morphologic variability may exist within a single tumor and between different tumors. The aim of this study was to examine the role of DOG1 (discovered on gastrointestinal tumor-1) and p63 immunohistochemistry in the diagnosis and differential diagnosis of salivary carcinomas. METHODS we examined the expression of DOG1 and p63 immunohistochemistry in 33 mucoepidermoid carcinomas (MEC), 9 acinic cell carcinomas (ACC), 10 adenoid cystic carcinomas (AdCC) and 4 myoepithelial carcinomas. RESULTS All ACC showed strong to moderate positivity for DOG1 (P=0.001) and all were totally negative for p63. All MEC expressed strong to moderate positivity for p63 (P=0.001) while only (9.1%) were weak to moderately positive for DOG1. (80%) AdCC were moderately positive for DOG1 in ductal and myoepithelial components and (100%) showed moderate positivity for p63 in myoepithelial cells only (P=0.001). All myoepithelial carcinomas were DOG1 negative, 2 (50%) were weakly positive for p63 while the other 2 were moderately positive (P=0.5). CONCLUSION DOG1 is a sensitive marker in the diagnosis of acinic cell carcinoma, p63 is sensitive in the diagnosis of mucoepidermoid carcinoma, the combined use of both markers is helpful and statistically significant in the differential diagnosis of acinic cell carcinoma versus mucoepidermoid carcinoma, both markers can help in the diagnosis of adenoid cystic carcinoma but they have no role in the diagnosis of myoepithelial carcinoma.