MYB, CD117 and SOX-10 expression in cutaneous adnexal tumors.

Background: Elevated MYB expression has been documented in adenoid cystic carcinoma (ACC), cylindroma, and spiradenoma, but the specificity of this finding is unknown. CD117 and SOX-10 expression also occurs in some cutaneous adnexal tumors. This study assesses MYB, CD117 and SOX-10 expression in cutaneous adnexal tumors.

Methods: Retrospective analysis of 184 benign adnexal tumors (140 eccrine/apocrine, 40 follicular and 10 sebaceous), and 30 malignant adnexal tumors was performed with MYB, SOX-10 and CD117 immunostaining.

Results: In the benign adnexal tumors, 16% (23/140) significantly expressed MYB. MYB expression was limited to cylindromas and to a lesser extent, spiradenomas in the benign cohort. Elevated MYB expression was detected in mucinous carcinoma, endocrine mucin-producing sweat gland carcinoma and 1 and 4 cases of extramammary Paget's disease (EMPD) in the malignant cohort. CD117 and SOX-10 had similar overall positivity rates in benign apocrine and eccrine tumors (45% and 68% respectively), and were generally negative in other benign and malignant adnexal tumors.

Conclusions: Expression of MYB appears limited to a small number of cutaneous adnexal tumors, including cylindromas, spiradenomas, ACCs, mucinous carcinoma, endocrine mucin-producing sweat gland carcinoma and some cases of EMPD.