Reflectance confocal microscopy for noninvasive monitoring of therapy and detection of subclinical actinic keratoses.

BACKGROUND Actinic keratoses (AK) represent cutaneous carcinoma in situ and have previously been evaluated by reflectance confocal microscopy (RCM). Treatment of AK with imiquimod (IMIQ) 5% cream has been shown to 'highlight' subclinical lesions. OBJECTIVE The aim of this study was to test the applicability of RCM for noninvasive monitoring of actinic field cancerization and detection of subclinical AK. SUBJECTS AND METHODS AK and surrounding skin sites with no apparent AK of 11 volunteers were selected for imaging and subsequently classified as 'clinical' and 'subclinical' AK. IMIQ was used 3 times weekly for 4 weeks. RESULTS RCM was able to detect morphologic features of AK in both clinical and subclinical AK; features were more pronounced in clinical lesions. The immunomodulatory response induced by IMIQ was visualized by RCM. CONCLUSION Our findings indicate that RCM allows noninvasive monitoring of treatment response in vivo and permits early detection of subclinical AK, thus substantiating the incentive for therapy.