Histological features and immunophenotyping of metaplastic breast carcinoma with melanocytic differentiation
ZHANG Jianbin
HAN Shengchun
LI Lifeng
YAN Shaohui
Abstract：Objective To investigate the histopathological characteristics,immunophenotypic features,and diagnostic criteria of metaplastic breast carcinoma(squamous cell carcinoma subtype)with melanocytic differentiation,supplemented by a literature review.Methods A retrospective analysis was conducted on the clinical,imaging,histopathological,and immunohistochemical data of a 45-year-old female patient with a left breast mass diagnosed in 2024.Tumor tissues were subjected to HE staining and immunohistochemical analysis(including CK5/6,p63,p40,HMB-45,Melan-A,S-100,SOX10,ER,PR,HER2,etc.).The diagnosis was established by integrating morphological and immunohistochemical findings,followed by a review of relevant literature to summarize diagnostic and differential features.Results The patient was a 45 year old female,and breast ultrasound examination revealed a solid hypoechoic breast mass(BI-RADS category 4C).Histologically,the tumor exhibited typical squamous cell carcinoma architecture with focal true melanin deposition(accounting for 30％of the tumor area).Immunohistochemistry revealed that the tumor cells were positive for CK5/6,p63,and p40,focally positive for HMB-45,Melan-A,and S-100,while negative for SOX10,ER,PR,and HER2.The Ki-67 proliferation index was approximately 50％.Based on these findings,the tumor was diagnosed as metaplastic breast carcinoma(squamous cell carcinoma subtype)with melanocytic differentiation.The patient recovered well following radical mastectomy and adjuvant chemotherapy,with no recurrence during 6-month follow-up.Conclusion Metaplastic breast carcinoma may rarely exhibit melanocytic differentiation,which is easily confused with malignant melanoma and other conditions.Accurate diagnosis depends on the combined assessment of morphological features and immunohistochemical staining results.Recognition of this variant is essential to avoid misdiagnosis and guide personalized treatment.
Keywords：Metaplastic breast carcinomaSquamous cell carcinomaMelanocytic differentiationTriple-negative breast cancerImmunohistochemistryPathological diagnosis
Publication Date：2025-09-28
Online Publishing Date：2025-11-13(First online date of this platform, not the publication date of the document)
Pages：5( 1151-1155 )