Risk of synchronous and metachronous second nonmelanoma skin cancer when referred for Mohs micrographic surgery

Background: Patients with basal cell carcinoma and cutaneous squamous cell carcinoma are at substantial risk for the onset of a second nonmelanoma ski n cancer (NMSC). Objective: Our purpose was to determine the incidence of multiple (synchron ous) NMSC at presentation to an academic Mohs micrographic surgery referral center and to note the incidence of second lesions occurring in a metachro nous fashion. Methods: A retrospective study was conducted of 456 consecutive patients wh o presented for Mohs surgery over a 2-year period. Patients were assessed a t initial visits for the presence of multiple NMSCs and were subsequently e xamined over 2 years for the onset of new NMSCs. Results: More than 39% of patients initially referred for Mohs surgery with a basal cell or squamous cell carcinoma either presented with multiple pri mary lesions or experienced a subsequent NMSC within 2 years. These tumors were divided almost equally between multiple primary NMSC at presentation a nd subsequent (metachronous) tumors. Conclusion: Patients referred for Mohs surgery in an academic setting are a select group at extremely high risk of additional NMSCs at or shortly afte r presentation for the index lesion.