Background and Objectives: Low-grade triple-negative breast carcinomas (LG-TNBCs) represent a rare subset of breast cancers that deviate from the aggressive clinical course typically associated with triple-negative tumors. This narrative review aims to consolidate current knowledge on LG-TNBCs, highlighting their diagnostic features, molecular characteristics, and clinical implications to guide appropriate patient management and prevent overtreatment.Materials and Methods: We conducted a comprehensive narrative review using PubMed/MEDLINE, Embase, and Scopus databases up to September 2025. Search terms included combinations of “triple-negative breast carcinoma”, “low-grade”, “adenoid cystic carcinoma”, “secretory carcinoma”, “acinic cell carcinoma”, “tall cell carcinoma with reversed polarity”, “low-grade adenosquamous carcinoma”, and “fibromatosis-like metaplastic carcinoma.” Studies reporting clinicopathologic, immunohistochemical, or molecular data were included.Results:LG-TNBCs include seven distinct entities: adenoid cystic carcinoma, secretory carcinoma, acinic cell carcinoma, tall cell carcinoma with reversed polarity, low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, and mucoepidermoid carcinoma. These neoplasms are characterized by distinct morphologic patterns, specific immunohistochemical profiles, and recurrent molecular alterations such as ETV6-NTRK3 fusions and MYB rearrangements. Despite their triple-negative immunoprofile, they demonstrate indolent clinical behavior with excellent prognosis and low metastatic potential, although local recurrence is reported in variants exhibiting infiltrative, locally aggressive behavior.Conclusions:Recognition of LG-TNBCs is essential to prevent overtreatment and guide personalized patient management. Molecular characterization provides diagnostic confirmation and therapeutic opportunities, particularly for NTRK-fusion-positive tumors treatable with targeted inhibitors, highlighting the importance of precision medicine in rare breast tumors.
**背景与目的：** 低级别三阴性乳腺癌（LG-TNBCs）是一类罕见的三阴性乳腺癌亚型，其临床病程与通常具有侵袭性的三阴性肿瘤不同。本文旨在整合当前关于LG-TNBCs的知识，重点阐述其诊断特征、分子特性及临床意义，以指导患者合理管理并避免过度治疗。 **材料与方法：** 我们通过检索截至2025年9月的PubMed/MEDLINE、Embase和Scopus数据库，进行了全面的叙述性综述。检索词包括“三阴性乳腺癌”、“低级别”、“腺样囊性癌”、“分泌性癌”、“腺泡细胞癌”、“极性倒转的高细胞癌”、“低级别腺鳞癌”和“纤维瘤病样化生性癌”的组合。纳入的研究需报告临床病理学、免疫组织化学或分子数据。 **结果：** LG-TNBCs包括七种独立类型：腺样囊性癌、分泌性癌、腺泡细胞癌、极性倒转的高细胞癌、低级别腺鳞癌、纤维瘤病样化生性癌和黏液表皮样癌。这些肿瘤具有独特的形态学模式、特异的免疫组化特征以及反复出现的分子改变（如ETV6-NTRK3融合和MYB重排）。尽管其免疫表型为三阴性，但临床行为惰性，预后良好且转移潜能低；不过，部分具有浸润性或局部侵袭性行为的亚型存在局部复发的报道。 **结论：** 识别LG-TNBCs对于避免过度治疗和指导个体化患者管理至关重要。分子特征分析可提供诊断确认和治疗机会，特别是对于可靶向抑制剂治疗的NTRK融合阳性肿瘤，凸显了精准医学在罕见乳腺肿瘤中的重要性。
Seven Shades of Triple Negativity: A Review Unveiling the Low-Grade Spectrum of Breast Cancer
肿瘤(癌症)患者之家