Factors predictive of complex Mohs surgery cases

Abstract Background: Mohs surgery allows excision of skin cancer in a tissue-sparing fashion that minimizes recurrence risk. While the indications for Mohs surgery are well established, factors predictive of complex Mohs cases are less studied. Objective: To determine patient, tumor, and surgeon characteristics associated with complex Mohs cases. Methods: A retrospective review was performed for a 3-year period (7/2006-6/2009) to identify Mohs cases requiring ≥4 stages ("complex"), and a control population requiring ≤3 stages ("non-complex"). Surgical logs for four fellowship-trained Mohs surgeons were reviewed. Results: 77 complex cases (51 academic practice vs. 26 private practice) were compared with 154 control cases (102 academic practice vs. 52 private practice). There were no significant differences in patient age, gender, immunosuppression, academic (2.7% complex) versus private practice (3.5% complex), or surgeons' years of experience. Factors associated with complexity included: recurrent tumors (p < 0.001; odds ratio (OR) 6.88; 95% confidence interval (CI) 2.8-17); basal cell carcinoma (BCC) with infiltrative or morpheaform histology (p = 0.0019; OR 3.0; 95% CI 1.5-6.3); tumors of the nose (p = 0.0168; OR 2.05; 95% CI 1.1-3.7), especially nasal tip (p = 0.0103; OR 3.68; 95% CI 1.3-10.6) and ear (p = 0.0178; OR 3.0; 95% CI 1.2-7.9), especially helix (p = 0.00744; OR 5.9; 95% CI 1.5-22.7); tumors with pre-operative size >1 cm (p = 0.018; OR 2.0; 95% CI 1.1-3.6); and tumors involving >1 cosmetic subunit (p = 0.0072; OR 5.0; 95% CI 1.5-16.7). Complex tumors had greater post-operative area (10.6 ± 1.3 vs. 3.6 ± 0.7 cm(2); p < 0.0001), and more often required flap/graft repair (p < 0.0001; OR 6.9; 95% CI 3.7-13.1). Limitations: A retrospective study representing a single geographic area. Conclusions: Mohs cases are similar in complexity whether in academic or private practice. Recurrent/aggressive histology tumors, tumors >1 cm, and tumors on the nose or ear are more likely to prove surgically complex. Advanced knowledge of these factors may be useful pre-operatively as Mohs surgeons plan their scheduled cases.