A direct immunohistochemistry (IHC) method improves the intraoperative diagnosis of breast papillary lesions including breast cancer.

AIMS: The goal of this study is to evaluate a novel direct immunohistochemistry staining method on frozen tissues for the intraoperative diagnosis of breast papillary lesions. METHODS AND RESULTS: Keratin 5 (CK5) and smooth muscle myosin heavy chain (SMMHC) antibodies were labeled with horseradish peroxidase polymers and used for direct immunohistochemistry (IHC) staining on frozen sections of breast tissues during surgical operations. The results from direct IHC on 102 cases of breast papillary lesions were compared with those obtained by the conventional staining method on formalin-fixed paraffin-embedded tissues (FFPE). Compared to the conventional method, direct IHC staining can significantly improve the accuracy of intraoperative diagnosis of breast papillary lesions from 70% to 97% (p < 0.01). No false negative cases were found with direct IHC in this study. In comparison, 53% of cases with the conventional method were found false negative. Direct IHC also significantly reduced the deferred diagnosis rate from 21% to 3% (p < 0.01). Furthermore, the entire procedure of direct IHC can be finished within 10 minutes, which makes it more feasible for the use of intraoperative frozen section diagnosis. CONCLUSION: The direct IHC staining method can significantly improve the efficiency and accuracy of intraoperative diagnosis of breast papillary lesions. It also fits better for the quick turnaround time required for intraoperative diagnosis.