Background  Imiquimod 5% cream can reduce or clear superficial and small nodular basal cell carcinoma (BCC). It could be used as a pretreatment of Mohs micrographic surgery (MMS) to decrease defect size.

Objectives  To study if a pretreatment with imiquimod 5% cream decreases defect size after MMS. In addition, to study the effect on the number of Mohs stages and reconstruction time.

Methods  Seventy patients aged >18 years with a primary nodular BCC in the face were included. The imiquimod group used imiquimod 5% cream for 4 weeks, before MMS. The control group was treated with MMS only. Tumour and defect sizes were measured. We noted the number of Mohs stages, reconstruction time and side-effects.

Results  The median percentage increase in area from tumour size at baseline to the post-MMS defect for the imiquimod group was significantly less compared with the control group, 50% vs. 147% (< 0·001). A tendency towards fewer Mohs stages in the imiquimod group was observed and the reconstruction time was significantly shorter in this group (= 0·01).

Conclusions  Imiquimod 5% cream as pretreatment of MMS significantly reduced the tumour size in primary nodular BCC and reduced the surgical defect size. Further research is necessary to investigate cost-effectiveness.