Confocal laser microscopic imaging of actinic keratoses in vivo: A preliminary report

Background: Real-time near-infrared confocal laser scanning microscopy (CM) offers an unprecedented method for confirming the clinical diagnosis of ac tinic keratosis (AK) without biopsy. Methods: Seven patients with clinically diagnosed AK underwent CM imaging o ver the lesion and over adjacent normal-appearing skin. Biopsy specimens we re obtained From the presumed AKs in 4 patients. Results: CM detected lesional pathologic features of hyperkeratosis (71%), lower epidermal nuclear enlargement and pleomorphism (100%), and architectu ral disarray (57%). In contrast, cytologic atypia and architectural disarra y were apparent in one patient (17%) over the adjacent, clinically normal s kin. Three of 4 biopsy specimens confirmed the clinical diagnosis of AK, wh ereas one revealed invasive squamous cell carcinoma. Without optimizing CM for imaging hyperkeratotic skin lesions, the limited depth of penetration r eached the stratum basale in only 3 lesions, precluding detection of dermal invasion in the others. Conclusion: Depth of penetration currently imposes a major limitation on CM in the diagnosis of AKs, especially in hypertrophic and hyperkeratotic les ions, which are more likely to be malignant. However, CM may become an alte rnative to biopsy, and its limitations may be overcome by future technologi c advances in optical penetration or by simply removing the hyperkeratotic stratum corneum.