Use of Ultra-Fast One-Step CK5 IHC for Identifying BCC and SCC During Mohs Surgery

In a proof-of-concept study, researchers demonstrated the use of an ultra-fast, one-step immunohistochemistry (IHC) system utilizing a polymer of horseradish peroxidase (HRP) conjugated to a monoclonal antibody to cytokeratin 5 (CK5mab) for identifying basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) during Mohs surgery. The study involved 22 patients with biopsy-proven BCC or SCC, and a total of 62 specimens were stained with both hematoxylin and eosin (H/E) and one-step CK5mab during surgeries. The IHC results were compared with the final diagnosis after formalin-fixed paraffin-embedded (FFPE) permanent section H/E stain. The one-step IHC process was completed in less than 10 minutes, and the tumor cells of BCC and SCC were easily visualized and differentiated from normal skin structures. The results of intraoperative diagnosis based on H/E stains and CK5mab IHC stains were confirmed upon review of all sections with permanent section diagnosis. This one-step IHC represents a significant advancement in the interpretation of Mohs slides, particularly for poorly differentiated tumors.