Immunohistochemical Expression of SOX10 in Triple-Negative Breast Carcinoma and its Clinicopathological Significance

Background: Triple-negative breast cancer (TNBC) is an aggressive subtype lacking estrogen receptor (ER), progesterone receptor (PR), and HER2 expression. SOX10, a neural crest transcription factor, is implicated in TNBC pathogenesis, particularly basal-like subtypes. This study evaluated SOX10 expression in TNBC and its association with clinicopathological parameters. Methods: A cross-sectional study was conducted on 40 formalin-fixed paraffin-embedded (FFPE) TNBC tissue blocks (August 2023–March 2025). SOX10 immunohistochemistry (IHC) was performed using a rabbit monoclonal antibody (EP268). Staining was considered positive if >1% of tumor nuclei showed immunoreactivity and graded as patchy (1–10%), focal (11–70%), or diffuse (>70%). Associations with age, laterality, histologic subtype, grade, stage, and lymphovascular invasion (LVI) were analyzed using Chi-square/Fisher’s exact tests (SPSS v28.0; p<0.05 significant). Results: SOX10 expression was observed in 18/40 cases (45%). Expression significantly correlated with higher histologic grade (p<0.001): 50% of Grade 3 tumors were positive vs. 5.6% of Grade 1. Diffuse staining increased with grade (p=0.01). SOX10 positivity was also associated with advanced pathological T stage (T2-T4b; p<0.001). No significant associations were found with age, laterality, quadrant, histologic subtype, nodal status, AJCC stage, or LVI (p>0.05). The predominant subtype was invasive carcinoma of no special type (IBC-NST; 87.5%). Conclusion: SOX10 is expressed in nearly half of TNBCs and is significantly associated with high-grade and advanced T-stage disease, suggesting a role in tumor aggressiveness. It may serve as a valuable biomarker for risk stratification and a potential therapeutic target in TNBC.