Surgical treatment of basal cell carcinoma – a case series on factors influencing the risk of an incomplete primary excision

BACKGROUND: Basal cell carcinoma (BCC) is the most common skin cancer form and one first line treatment is surgical excision. Complete excision is vital to minimize risk of recurrence. Studies on occurrence of incomplete excisions have given diverse results and seldom include large populations from a dermatological setting. OBJECTIVES: The rate of positive surgical margins in primary surgery of BCC at a tertiary dermatology clinic is studied. Factors associated with an incomplete primary excision are analysed. METHODS: Patients scheduled for standard excision, without peri-operative margin control, of BCC during the years 2008-2015 were prospectively enrolled in the study. Tumour specific factors, including histopathologic subtype, as well as post-operative outcome were registered. Incomplete excisions were analysed in relation to patient- and tumour related factors. RESULTS: In total, 4.6% of 3911 BCC tumours were incompletely excised. The rate of incomplete excisions was higher for facial tumours and among tumours with an aggressive histological subtype. Morpheiform BCC on the nose or ear had the highest rate of an incomplete excision, 61.5% and 50% respectively. CONCLUSIONS: Most BCC, irrespective of subtype, were completely excised during the primary excision. Tumour sites nose and ears were associated with the highest rate of positive primary surgical margins, especially for infiltrative or morpheiform BCCs. Surgery with perioperative examination of margins is strongly recommended for these tumours.