Gao B B, Zheng Q, Yu L, Luo D J, Nie X, Xu X
Department of Pathology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
Zhonghua Bing Li Xue Za Zhi. 2022 Sep 8;51(9):843-849. doi: 10.3760/cma.j.cn112151-20220430-00356.
To investigate the clinicopathological features and HER2 expression of metaplastic squamous cell carcinoma (MSCC) of the breast. A total of 47 MSCC cases diagnosed in the Wuhan Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China from January 2010 to December 2021 were reviewed. The clinical information (including the follow-up data of HER2 positive patients) and pathological features were collected and analyzed. All of the patients were female. Among the 47 cases, 25 were pure squamous cell carcinoma (PSCC) and 22 were mixed metaplastic carcinoma with squamous cell component (MMSC). The median age of the patients was 54 years (range, 29-84 years). The maximum diameter of the mass ranged from 0.8 to 10.0 cm, with a mean value of 3.3 cm, 85.7% (24/28) of the cases were smaller than 5 cm, and only 4 cases were larger than or equal to 5 cm. 89.5% of the MMSC presented with a solid mass. Cystic changes were more commonly found in the PSCC group (50%, <0.05) than the MMSC group. 36.7% (11/30) of the patients had lymph node metastasis at the time of diagnosis. The squamous cell carcinoma component in all cases showed diffuse or patchy expression of p63, p40 and CK5/6. 55.3% (26/47) of the cases showed triple-negative phenotype. Among the 7 HER2-positive patients, 6 were MMSC group, which had a significantly higher rate of HER2-positivity than that in the PSCC group (1 case). In 1 MMSC case, immunohistochemistry showed HER2 2+in the invasive ductal carcinoma component and HER2 negativity (0) in the squamous cell carcinoma component, but HER2 FISH was negative in invasive ductal carcinoma and positive in squamous cell carcinoma component. Six HER2-positive MSCC patients received anti-HER2-targeted therapy, including two patients who received neoadjuvant chemotherapy combined with anti-HER2-targeted therapy before surgery. One patient achieved pathological complete remission, while the other achieved partial remission (the residual tumors were squamous cell carcinoma components). After 9-26 months of follow-up, four patients had no disease progression, two patients developed pulmonary metastases, and one patient showed local recurrence. MSCC is a group of heterogeneous diseases. PSCC and MMSC may be two different entities. Most of the MSCC are triple-negative and HER2 positivity is more commonly seen in MMSC with invasive ductal carcinoma component. Some HER2-positive MSCC patients can achieve complete remission or long-term progression-free survival after receiving anti-HER2 targeted therapy, but the squamous cell carcinoma component may be less sensitive to targeted therapy than the invasive ductal carcinoma component.
探讨乳腺化生性鳞状细胞癌（MSCC）的临床病理特征及HER2表达情况。回顾性分析了2010年1月至2021年12月在华中科技大学同济医学院附属武汉协和医院诊断的47例MSCC病例。收集并分析了临床资料（包括HER2阳性患者的随访数据）和病理特征。所有患者均为女性。47例中，25例为纯鳞状细胞癌（PSCC），22例为伴有鳞状细胞成分的混合化生癌（MMSC）。患者的中位年龄为54岁（范围29 - 84岁）。肿块最大直径为0.8至10.0 cm，平均值为3.3 cm，85.7%（24/28）的病例小于5 cm，仅4例大于或等于5 cm。89.5%的MMSC表现为实性肿块。PSCC组（50%，<0.05）比MMSC组更常见囊性改变。36.7%（11/30）的患者在诊断时出现淋巴结转移。所有病例的鳞状细胞癌成分均显示p63、p40和CK5/6弥漫性或斑片状表达。55.3%（26/47）的病例表现为三阴性表型。7例HER2阳性患者中，6例为MMSC组，其HER2阳性率显著高于PSCC组（1例）。1例MMSC病例中，免疫组化显示浸润性导管癌成分HER2 2+，鳞状细胞癌成分HER2阴性（0），但浸润性导管癌HER2 FISH阴性，鳞状细胞癌成分阳性。6例HER2阳性MSCC患者接受了抗HER2靶向治疗，其中2例患者在手术前接受了新辅助化疗联合抗HER2靶向治疗。1例患者达到病理完全缓解，另1例达到部分缓解（残留肿瘤为鳞状细胞癌成分）。随访9 - 26个月后，4例患者无疾病进展，2例患者发生肺转移，1例患者出现局部复发。MSCC是一组异质性疾病。PSCC和MMSC可能是两种不同的实体。大多数MSCC为三阴性，HER2阳性更常见于伴有浸润性导管癌成分的MMSC。部分HER2阳性MSCC患者接受抗HER2靶向治疗后可实现完全缓解或长期无进展生存，但鳞状细胞癌成分可能比浸润性导管癌成分对靶向治疗敏感性更低。
