Poling Justin S, Yonescu Raluca, Subhawong Andrea P, Sharma Rajni, Argani Pedram, Ning Yi, Cimino-Mathews Ashley
Departments of *Pathology †Oncology, The Johns Hopkins Hospital, Baltimore, MD.
Am J Surg Pathol. 2017 Jul;41(7):973-979. doi: 10.1097/PAS.0000000000000878.
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-NFIB gene 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 MYB fluorescence 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. MYB rearrangement 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 MYB fluorescence 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.
乳腺腺样囊性癌（ACC）是一种原发性乳腺癌，与涎腺ACC一样，具有t(6;9)易位，导致MYB-NFIB基因融合，免疫组化（IHC）显示MYB免疫阳性。然而，MYB免疫反应性或重排是否可用于支持对恶性基底样或良性筛状乳腺病变的ACC诊断，目前尚未明确。对原发性乳腺ACC（n = 11）、胶原球样变性（CS；n = 7）和微腺性腺病（MGA；n = 5）的全切片以及包含16例基底样三阴性乳腺癌（TNBC）的组织芯片进行IHC检测MYB，并使用断裂分离探针进行MYB荧光原位杂交。100%的ACC可见强而弥漫的核MYB标记，而基底样TNBC、CS或MGA均无此现象（P = 0.0001）。100%的ACC可见任何程度的核MYB标记，而所有其他病例为54%（P = 0.007），71%的CS、63%的基底样TNBC和0%的MGA可见任何标记。89%（8/9）的可评估ACC检测到MYB重排，而所有其他可评估病例为4%（1/26）（P = 0.0001），1例（7%；n = 1/15）可评估的基底样TNBC检测到重排。对于乳腺ACC，MYB强而弥漫的核标记比MYB荧光原位杂交更敏感，可用于支持对乳腺筛状或基底样病变的ACC诊断。然而，弱而局灶性标记应谨慎解释，因为在其他良性筛状和恶性基底样病变中也可见到。
