Perineural spread of basal cell carcinomas treated with Mohs micrographic surgery

BACKGROUND. Perineural spread is a well-documented feature of cutaneous tum ors and may portend a more aggressive course. The incidence of perineural i nvasion 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 inflamma tion and invasion in tumors requiring more than one stage of surgery. They also documented the demographic features, clinical characteristics, histolo gic subtype, and operative data in each case. RESULTS. Seventy-eight BCCs required more than one stage of Mohs surgery. P erineural 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. Tumor s with perineural invasion required 5.3 surgical stages on average for clea rance, in contrast to tumors without perineural invasion, which required 2. 2 stages. Tumors with perineural inflammation, inflammation plus tumor inva sion, and invasion alone were, respectively, 138%, 149%, and 194% greater i n area preoperatively than tumors without perineural involvement, and their mean defect areas after Mohs surgery were, respectively, 151%, 121%, and 6 05% larger than those of tumors without perineural involvement. CONCLUSIONS. The incidence of perineural invasion among cases of BCC appear s higher than previously recognized. Tumor aggressiveness appears to correl ate with the presence of perineural invasion. Surgery with horizontal froze n-section margin control enables easy detection of perineural involvement a nd should therefore be strongly considered for the treatment of high risk B CC patients. (C) 2000 American Cancer Society.