Objective: To investigate the clinicopathological characteristics of breast squamous cell carcinoma and to analyze the relationship between its immune microenvironment tumor infiltrating lymphocytes (TILs) and prognosis. Methods: Forty-four cases of primary squamous cell carcinoma of the breast diagnosed and treated in the First Affiliated Hospital of Air Force Medical University, Xi'an, China from January 2006 to July 2022 were selected. Their clinicopathological characteristics were analyzed. The cell composition of TILs was evaluated using immunohistochemistry (Mainly markers of B lymphocytes, T lymphocytes and plasma cells). The relationship between TILs and prognosis was also analyzed. Results: The 44 patients of breast squamous cell carcinoma were all female and all were invasive carcinoma. Eight cases (8/44, 18.2%) were squamous cell carcinoma, while 36 cases (36/44, 81.8%) were mixed squamous cell carcinoma. The mixed components included non-specific carcinoma and spindle cell metaplastic carcinoma (17 cases each). One case contained ductal carcinoma in situ of the breast and 1 case contained tubular carcinoma. The proportion of squamous cell carcinoma was 10% to 90%. The cases with pure squamous cell carcinoma often had a large cystic cavity, which was lined by atypical squamous epithelium, while infiltrating squamous cell carcinoma nests were seen in the breast tissue around the cystic cavity. Immunohistochemical staining showed that p63 and CK5/6 were expressed in the squamous cell carcinoma component, but ER, PR and HER2 were not, except for one case of HER2 1+. The positive rates of TRPS1 and PDL-1 were 76% and less than 1%, respectively. Fifteen cases were in the high TILs group (TILs≥30%) and 29 cases were in the low TILs group (TILs<30%). Twenty-three patients were followed up for 5 to 118 months. Among them, 12 died within 3 years and 9 were alive at the end of the follow up. There was no significant difference in TNM stage, TILs and prognosis between simple squamous cell carcinoma and mixed squamous cell carcinoma. Conclusions: Breast squamous cell carcinoma can be divided into simple squamous cell carcinoma and mixed squamous cell carcinoma. There are differences in gross findings and histology between the simple and mixed squamous cell carcinoma of the breast. Sufficient samples should be taken to avoid missing the diagnosis of a minor squamous component. The prognosis of patients with high TILs is significantly better than that of patients with low TILs. The expression rate of TRPS1 in primary squamous cell carcinoma of breast is high and helpful to the differential diagnosis from metastatic squamous cell carcinoma.
目的： 探讨乳腺鳞状细胞癌临床病理学特征，分析其免疫微环境肿瘤浸润淋巴细胞（tumor infiltrating lymphocytes，TILs）与预后的关系。 方法： 收集空军军医大学第一附属医院2006年1月至2022年7月诊治的乳腺鳞状细胞癌44例，分析其临床病理学特点，评估TILs、免疫组织化学检测TILs的细胞组成（主要包括B淋巴细胞、T淋巴细胞及浆细胞），并分析和预后的关系。 结果： 44例患者均为女性，均为浸润性癌。8例（8/44，18.2%）为单纯性鳞状细胞癌，36例（36/44，81.8%）为混合性鳞状细胞癌，混合性成分主要为非特殊型浸润性癌和梭形细胞化生性癌（各17例），1例仅合并乳腺导管原位癌成分，1例合并小管癌，鳞状细胞癌的成分占比10%~90%。单纯性鳞状细胞癌常有大的囊腔，囊腔内衬不同异型程度的鳞状上皮，囊腔周围乳腺组织中可见浸润性生长的鳞状细胞癌巢。免疫组织化学染色显示，鳞状细胞癌成分均表达p63和细胞角蛋白5/6，除1例HER2 1+外，均不表达雌激素受体、孕激素受体和HER2；TRPS1表达率76%；PD-L1表达均<1%。15例为高TILs组（TILs≥30%）、29例为低TILs组（TILs<30%）。23例患者获随访，随访时间5~118个月，其中12例在3年内死亡，9例存活。单纯性鳞状细胞癌和混合性鳞状细胞癌的TNM分期、TILs及预后，差异均无统计学意义（P>0.05）。高TILs组患者预后相比低TILs组较好，单纯性鳞状细胞患者预后相比混合性鳞状细胞癌较好，差异无统计学意义（P>0.05）。 结论： 乳腺鳞状细胞癌分为单纯性鳞状细胞癌和混合性鳞状细胞癌。乳腺单纯性和混合性鳞状细胞癌的大体检查、组织学有差异，应充分取材避免漏诊占比少的肿瘤成分。高TILs组患者预后相比低TILs组较好，但PD-L1表达低，提示不适合免疫治疗。乳腺原发鳞状细胞癌TRPS1表达率较高，可协助与转移性鳞状细胞癌鉴别。.