MYB Labeling by Immunohistochemistry Is More Sensitive and Specific for Breast Adenoid Cystic Carcinoma than MYBLabeling by FISH

Autor: Poling, Justin S., Yonescu, Raluca, Subhawong, Andrea P., Sharma, Rajni, Argani, Pedram, Ning, Yi, Cimino-Mathews, Ashley
Zdroj: The American Journal of Surgical Pathology; July 2017, Vol. 41 Issue: 7 p973-979, 7p
Abstrakt: Breast adenoid cystic carcinoma (ACC) is a primary breast carcinoma that, like salivary gland ACC, displays the t(6;9) translocation resulting in the MYB-NFIBgene fusion and immunopositivity for MYB by immunohistochemistry (IHC). However, it is not well established whether MYB immunoreactivity or rearrangement can be used to support a diagnosis of ACC in a malignant basaloid or benign cribriform breast lesion. Whole sections of primary breast ACC (n=11), collagenous spherulosis (CS; n=7), and microglandular adenosis (MGA; n=5) and tissue microarrays containing 16 basal-like, triple-negative breast carcinomas (TNBC) were labeled for MYB by IHC and underwent MYBfluorescence in situ hybridization using a break-apart probe. Strong, diffuse nuclear MYB labeling was seen in 100% ACC compared with no cases of basal-like TNBC, CS, or MGA (P=0.0001). Any degree of nuclear MYB labeling was seen in 100% ACC compared with 54% of all other cases (P=0.007), with any labeling seen in 71% CS, 63% basal-like TNBC, and 0% MGA. MYBrearrangement was detected in 89% (8/9) of evaluable ACC compared with 4% (1/26) of all other evaluable cases (P=0.0001), with a rearrangement detected in 1 (7%; n=1/15) evaluable basal-like TNBC. Strong, diffuse nuclear labeling for MYB is more sensitive than MYBfluorescence in situ hybridization for breast ACC and can be used to support a diagnosis of ACC in a cribriform or basaloid lesion in the breast. However, weak and focal labeling should be interpreted with caution as it can be seen in other benign cribriform and malignant basaloid lesions.
Databáze: Supplemental Index