Expression of MYB protein and its clinicopathological significance in adenoid cystic carcinoma of salivary gland

Objective: Recent studies revealed the existence of ectopic gene at t(6;9)(q22-23;p23-24) in adenoid cystic carcinoma (ACC), resulting in MYB-NFIB fusion gene formation. In this study, we discuss the expression of MYB of ACC in salivary gland and its clinicopathological significance. Methods: We examined 98 samples of salivary gland adenoid cystic carcinoma and 68 samples of salivary non-ACC neoplasms among patients at the Department of Oral Pathology, Nanjing Stomatological Hospital, Medical School of Nanjing University (China). The expression of Ki67 and MYB was analyzed by immunohistochemical analysis and followed up with survival analysis. Results: Of the 98 cases of salivary ACC, 87 (88.8%) stained positive for MYB, including 59.2% (58/98) strongly positive and 29.6% (29/98) weakly positive. Among the non-ACC neoplasms, 11.8% (8/68) cases stained weakly positive for MYB. No salivary gland tissue adjacent to ACC (0/20) or salivary gland tissue of non-neoplastic lesions (including submandibular gland calculus and inflammation) (0/5) was MYB positive. No significant relation was seen between MYB expression and age, gender, size, site, histological type, distant metastasis, Ki67 proliferation index and prognosis. Conclusion: Immunohistochemical analysis of MYB facilitates clinical pathological diagnosis and differential diagnosis of ACC in salivary gland. A strong positive expression of MYB is a significant ACC-specific marker in salivary gland.