Perineural spread of basal cell carcinomas treated with Mohs micrographic surgery

BACKGROUND. Perineural spread is a well-documented feature of cutaneous tumors and may portend a more aggressive course. The incidence of perineural invasion in basal cell carcinoma (BCC) is reportedly 1%. The authors sought to determine whether perineural spread occurs more commonly than previously thought. METHODS. The authors prospectively evaluated 434 patients with BCC treated with Mohs surgery, assessing the presence or absence of perineural inflammation and invasion in tumors requiring more than one stage of surgery. They also documented the demographic features, clinical characteristics, histologic subtype, and operative data in each case. RESULTS. Seventy-eight BCCs required more than one stage of Mohs surgery. Perineural inflammation, perineural tumor invasion, or both were present in 29 of the 78 tumors (37%), or 6.7% of all 434 prospectively evaluated cases. Twenty-one of the 78 tumors (26.9%) exhibited perineural inflammation, 3 (3.8%) demonstrated perineural invasion, and 5 (6.4%) exhibited both. Tumors with perineural invasion required 5.3 surgical stages on average for clearance, in contrast to tumors without perineural invasion, which required 2.2 stages. Tumors with perineural inflammation, inflammation plus tumor invasion, and invasion alone were, respectively, 138%, 149%, and 194% greater in area preoperatively than tumors without perineural involvement, and their mean defect areas after Mohs surgery were, respectively, 151%, 121%, and 605% larger than those of tumors without perineural involvement. CONCLUSIONS. The incidence of perineural invasion among cases of BCC appears higher than previously recognized. Tumor aggressiveness appears to correlate with the presence of perineural invasion. Surgery with horizontal frozen-section margin control enables easy detection of perineural involvement and should therefore be strongly considered for the treatment of high risk BCC patients. (C) 2000 American Cancer Society.