Treatment of actinic keratosis with imiquimod cream is expected to cause changes in the genes that are turned on, and turned off, by skin cells. Some of the drug induced changes in skin cells should also be visible using a special microscope. This study examines both types of changes.

The primary objective of this study was to assess apoptosis by examining the gene expression profiles of actinic keratosis (AK) lesions that were treated with imiquimod 5% cream or vehicle cream once daily 3 times per week for 4 weeks. Secondary objectives were to assess the utility of confocal microscopy (CM) to visually track cellular response to treatment with study cream compared with clinical and histological evaluations, and to evaluate the safety of treatment with imiquimod in subjects with AK on the balding scalp.

Inclusion Criteria:

• Have actinic keratoses on balding scalp
• Discontinuation of tanning bed use
• Discontinuation of moisturizers
• Avoidance of retinol products

Exclusion Criteria:

• Uncontrolled, clinically significant medical condition
• Dermatologic disease other than actinic keratosis in treatment area