{Reference Type}: Journal Article
{Title}: MYB expression by immunohistochemistry is highly specific and sensitive for detection of solid variant of adenoid cystic carcinoma of the breast among all triple-negative breast cancers.
{Author}: Batra H;Bose PSC;Ding Y;Dai A;Chen H;Albarracin CT;Sun H;Sahin AA;Yang F;Wistuba II;Raso MG;
{Journal}: Histopathology
{Volume}: 85
{Issue}: 3
{Year}: 2024 Sep 8
{Factor}: 7.778
{DOI}: 10.1111/his.15276
{Abstract}: <B>BACKGROUND: </B>Adenoid cystic carcinoma is a rare subtype of triple-negative breast carcinoma. These low-grade tumours, which are treated by simple mastectomy and have an excellent prognosis compared to other triple-negative breast carcinomas. Solid-variant adenoid cystic carcinomas have basaloid features and are difficult to distinguish morphologically from other triple-negative breast cancers. Breast adenoid cystic carcinoma exhibits MYB protein overexpression, which can be detected by immunohistochemistry (IHC).<BR><B>OBJECTIVE: </B>We compared the IHC expression of MYB in solid-variant adenoid cystic carcinoma with that in other triple-negative breast cancers.<BR><B>METHODS: </B>We conducted IHC staining of 210 samples of triple-negative breast cancers, including solid-variant adenoid cystic carcinoma (n = 17), metaplastic breast carcinoma (n = 44), basaloid triple-negative breast cancer (n = 21), and other triple-negative invasive ductal carcinoma (n = 128). We classified nuclear staining of MYB as diffuse/strong (3+), focal moderate (2+), focal weak (1+), or none (0).<BR><B>RESULTS: </B>All 17 solid/basaloid adenoid cystic carcinoma cases exhibited 3+ MYB expression. Of the 21 solid/basaloid triple-negative breast cancers, one (5%) had 2+ expression, seven (33%) 1+ expression, and 13 (62%) 0 expression. Of the 44 metaplastic carcinoma cases, 39 cases (89%) had no (0) staining, and the other five cases had focal weak (1+) or moderate (2+) staining. Among the 128 triple-negative invasive ductal carcinoma cases, 92 cases (72%) had no (0) staining, 36 cases (28%) exhibited focal weak (1+) or moderate (2+) staining.<BR><B>CONCLUSIONS: </B>Our study revealed diffuse/strong MYB staining (3+) only in solid/basaloid adenoid cystic carcinomas. Thus, we recommend routine MYB IHC staining in triple-negative breast carcinoma with solid/basaloid morphology to improve diagnostic accuracy.