Toluidine Blue and Hematoxylin and Eosin Stains are Comparable in Evaluating Squamous Cell Carcinoma During Mohs.

BACKGROUND: Histologic examination of tissue is the foundation of Mohs micrographic surgery because determination of surgical margins influences whether additional tissue will be taken. Currently, there is no large focused study comparing toluidine blue (TB) and hematoxylin and eosin (H&E) stains in the evaluation of squamous cell carcinoma (SCC). OBJECTIVE: This study evaluates whether TB and H&E are comparable in assessing the presence of tumor in frozen sections of SCC. MATERIALS AND METHODS: One hundred eighty-six randomized slides representing 93 tissue pieces from 36 tumors were examined by 3 Mohs surgeons (1 Accreditation Council for Graduate Medical Education fellow and 2 fellowship-trained surgeons) and compared using a template that documented the presence and location of tumor on the slides. RESULTS: The evaluation of SCC with H&E and TB stains was highly concordant, with concordant identification of SCC in 96%, 96%, and 94% of tissue layers among the 3 Mohs surgeons ARS, LHG, and AK-A, respectively. CONCLUSION: Toluidine blue and H&E stains are statistically similar in their ability to detect SCC and guide Mohs surgical decision-making.