Department of Pathology and Laboratory Medicine, Perelman School of Medicine and Hospital of the University of Pennsylvania, Pennsylvania, PA, USA.
Department of Pathology, Mount Sinai Hospital and Icahn School of Medicine, New York, NY, USA.
Histopathology. 2018 Dec;73(6):897-903. doi: 10.1111/his.13708. Epub 2018 Oct 22.
Adenomyoepithelioma (AME) and adenoid cystic carcinoma (ACC) of the breast have been noted to occur simultaneously, raising the possibility that AME may represent a related or precursor lesion to ACC. ACC frequently harbours genetic rearrangement of the MYB gene. We sought to clarify the relationship between AME and ACC by comparing their rates of MYB expression by IHC and MYB rearrangement by FISH.
IHC and FISH for MYB rearrangement were performed on paraffin-embedded sections of 11 breast ACCs, 11 non-breast ACCs and 11 breast-AMEs. Using FISH, five of eight (63%) interpretable breast ACCs demonstrated MYB gene rearrangement. Nine of 11 (81%) breast ACCs demonstrated MYB expression (range = 20-95%). Of the three FISH-negative breast ACCs, two were solid variant and demonstrated strong MYB expression by IHC. Of the 10 interpretable non-breast ACCs, six showed MYB rearrangement, all of which were conventional type. Nine of these 11 (81%) cases showed MYB immunoexpression (range = 10-90%), including three solid-variant cases which were negative by FISH. No MYB rearrangements were detected by FISH in 10 interpretable AMEs. However, three of 11 cases (27%) showed weak to moderate MYB expression by IHC (range = 10-40%).
Our results indicate that AMEs do not harbour MYB gene rearrangement. IHC for MYB may be helpful in diagnosing FISH-negative cases of ACC, particularly the diagnostically more difficult solid variants. However, weak to moderate MYB expression in a subset of AMEs highlights not only a potential diagnostic pitfall, but also shared pathophysiology with ACC worth investigating further at the genomic level.
乳腺的腺肌上皮瘤（AME）和腺样囊性癌（ACC）已被发现同时发生，这使得 AME 可能代表 ACC 的相关或前体病变。ACC 常存在 MYB 基因的遗传重排。我们通过比较免疫组化（IHC）检测 MYB 表达和荧光原位杂交（FISH）检测 MYB 重排，旨在阐明 AME 和 ACC 之间的关系。
对 11 例乳腺 ACC、11 例非乳腺 ACC 和 11 例乳腺 AME 的石蜡包埋切片进行了 IHC 和 FISH 检测 MYB 重排。使用 FISH，8 例（63%）可解释的乳腺 ACC 中有 5 例显示 MYB 基因重排。11 例乳腺 ACC 中有 9 例（81%）显示 MYB 表达（范围=20-95%）。在 3 例 FISH 阴性的乳腺 ACC 中，有 2 例为实性变异型，IHC 显示强 MYB 表达。在 10 例可解释的非乳腺 ACC 中，有 6 例显示 MYB 重排，均为常规型。这 11 例中有 9 例（81%）显示 MYB 免疫表达（范围=10-90%），包括 3 例 FISH 阴性的实性变异型。在 10 例可解释的 AME 中，均未通过 FISH 检测到 MYB 重排。然而，有 3 例（27%）IHC 显示弱至中度 MYB 表达（范围=10-40%）。
我们的结果表明 AME 不携带 MYB 基因重排。IHC 检测 MYB 可能有助于诊断 FISH 阴性的 ACC，尤其是更具诊断挑战性的实性变异型。然而，在一部分 AME 中出现弱至中度的 MYB 表达，不仅突出了潜在的诊断陷阱，还提示与 ACC 具有共同的病理生理学机制，值得进一步在基因组水平上进行研究。
