Confirmation of histological clearance of superficial basal cell carcinoma with multiple serial sectioning and Mohs' micrographic surgery following treatment with imiquimod 5% cream.

BACKGROUND

Although the effectiveness of daily dosing regimens of 5% imiquimod cream for the treatment of superficial basal cell carcinomas (sBCC) has been documented by recent studies, concerns about long-term outcome remain. The majority of efficacy data is based on clinical clearance and limited histological examination which may not identify tumour presence at the periphery.

OBJECTIVE

To assess the efficacy of 5% imiquimod cream for sBCC using detailed histological assessment 1 year after completion of treatment.

METHODS

Nine individuals with biopsy-proven sBCC treated with 5% imiquimod cream 1 year previously and who remained clinically clear were recruited. Paraffin-embedded excision specimens from the original tumour site were extensively examined by a dermatopathologist. Examination and analysis of frozen sections of the original tumour perimeter using Mohs' micrographic surgery (MMS) were then performed.

RESULTS

Eight of nine individuals, 89% (95% CI 56% to 97%) were histologically clear of sBCC at 52 weeks. One individual had a single focus of sBCC at one lateral margin.

CONCLUSION

The results show agreement between the clinical and histological assessment of tumour clearance. However, the persistence of disease in one patient, although limited, indicates the need for cautious long-term follow-up studies on the use of 5% imiquimod cream for sBCC.