(1) Low-grade adenosquamous carcinoma (LGASC) is a rare subtype of metaplastic breast carcinoma (MpBC), accounting for fewer than 0.05% of breast cancer cases. Unlike the typically aggressive nature of MpBCs, LGASC is an indolent tumor with an excellent prognosis. Due to its rarity, LGASC is frequently misdiagnosed, particularly in core needle biopsies. Currently, there are no clear treatment guidelines for LGASC. (2) Methods: This study presents a single-center retrospective analysis and a systematic literature review of LGASC. (3) Results: Three LGASC cases were diagnosed among 6462 breast cancer patients in our center, demonstrating its rarity. LGASC has overlapping features with benign sclerosing lesions and is often initially misdiagnosed. LGASC is often overtreated, as its indolent nature is not recognized. It very rarely presents axillary or distant metastases, and in contemporary data, local recurrences are rare, questioning the need for adjuvant therapy. (4) Conclusions: LGASC is a very rare form of breast cancer with an excellent prognosis despite being MpBC and usually a triple-negative breast cancer. It is often overtreated as its unique nature is not recognized.
(1) 低级别腺鳞癌是化生性乳腺癌的一种罕见亚型，占乳腺癌病例比例不足0.05%。与通常具有侵袭性的化生性乳腺癌不同，低级别腺鳞癌属于惰性肿瘤，预后良好。因其罕见性，该病常被误诊，尤其在空心针穿刺活检中。目前针对低级别腺鳞癌尚无明确的治疗指南。(2) 方法：本研究通过单中心回顾性分析与系统性文献综述探讨低级别腺鳞癌。(3) 结果：本中心6462例乳腺癌患者中仅确诊3例低级别腺鳞癌，印证其罕见性。该肿瘤与良性硬化性病变存在特征重叠，常被初诊误判。由于对其惰性本质认识不足，临床常存在过度治疗现象。腋窝或远处转移极为罕见，当代数据显示局部复发率低，这使辅助治疗的必要性受到质疑。(4) 结论：低级别腺鳞癌作为化生性乳腺癌且多为三阴性乳腺癌，虽属罕见类型但预后极佳。临床常因未能识别其独特性质而导致过度治疗。
肿瘤(癌症)患者之家