Optical coherence tomography imaging of non-melanoma skin cancer undergoing imiquimod therapy

To explore the application of optical coherence tomography (OCT) imaging of basal cell carcinomas (BCC) and actinic keratosis (AK) before, during and after imiquimod treatment and the ability of OCT to predict treatment outcome.

The study subjects were 20 patients with biopsy-verified BCC (9) or AK (11). Patients were OCT-scanned before, after 1 and 4 weeks of imiquimod treatment and after 3 months. Lesions were identified clinically and with OCT. Thickness and morphology of the lesions were recorded at each visit. Any remaining lesions were biopsied at follow-up.

Complete data sets were available for 16 patients (8 women and 8 men aged 52-82 years), four in-compliant patients were excluded. OCT identified all lesions. Previously suggested OCT-criteria identified 5/8 BCCs. Crusting, ulceration and active treatment significantly reduced image quality. All BCCs cleared, but at follow-up residual structures were seen clinically in 4 cases. OCT and histology both ruled out residual BCC. For AKs significant thinning occurred after 1 week of treatment (P = 0.04). Imiquimod cleared 2/8 AKs, and significantly decreased the thickness of all lesions (P = 0.02).

OCT could identify superficial BCC and AK before treatment. Monitoring during imiquimod treatment revealed impaired image quality most likely caused by inflammation, crusting and ulceration. On follow-up, OCT showed thinning of AKs indicating effect of treatment. All treated BCCs cleared, but where residual tissue was suspected clinically this could be ruled out by OCT.