[Complete treatment of basal cell carcinoma; cost effectiveness of Mohs micrographic surgery versus conventional...

To investigate whether Mohs micrographic surgery (MMS) in accordance with the indications in the revised guideline on basal cell carcinoma (BCC) more often leads to complete treatment than conventional excision (CE) and whether the costs are comparable, and to analyse whether this also applies to all primary BCC of the face.

Retrospective analysis.

We gathered data on 3374 MMS procedures and calculated per localisation, subtype and size: the percentage of CE that would have been incomplete after applying the recommended surgical margin; the surgical margin necessary to achieve complete excision in > 90% of cases; the final defect after CE and after MMS; the cost of MMS and the cost of CE with postponed reconstruction or, in the case of incomplete CE, subsequent MMS.

For the new MMS indications we can show that using MMS seems to prevent incomplete CE in 12-45% of cases. CE will also lead to incomplete excision in ≥ 10% of cases in most subgroups of primary facial BCC, with the exception of some small superficial or nodular BCCs in the H-zone. The final defect was always smaller after MMS than after CE. MMS can be used with comparable costs for primary BCCs > 5 mm in the H-zone and > 20 mm elsewhere in the face.

The surgical margins recommended in the guidelines are inadequate to achieve complete excision rates in > 90% of facial CEs. MMS is an efficient alternative for CE for primary BCCs > 5 mm in the H-zone and > 20 mm elsewhere in the face.