Pigmented lesions presenting on the face often pose a diagnostic challenge. This is due to the sensitivity of the area to standard management procedures, which often require invasive biopsies for diagnosis confirmation and management. In particular, lentigo maligna and pigmented actinic keratoses (AKs) often present with similar clinical presentations, often making differentiation difficult.1 Because of their prevalence in the cosmetically sensitive head and neck area, patients may want to avoid invasive procedures to treat these whenever possible. Noninvasive imaging tools can therefore be useful for such lesions, specifically in tracking lesion progression over time and minimizing scarring that can result from biopsies. While dermoscopy is perhaps the most wellknown tool used routinely to noninvasively examine lesions,2 reflectance confocal microscopy (RCM) has also emerged as a powerful tool in the evaluation of pigmented lesions.3

Background and Use

Dermoscopy is a noninvasive magnification device technique which combines magnification and light microscopy to aid in the examination and analysis of pigmented lesions based upon colors and structures of the epidermis, dermo-epidermal junction, and papillary dermis not seen by the unaided eye.2,4 Magnifications on different devices can range from 6x to 100x.2 While dermoscopy has been shown to improve accuracy in the diagnosis of skin cancer, particularly melanoma, it has not been as forthcoming in the differentiation of actinic keratoses and lentigo maligna.1,3 In a study of 89 flat facial pigmented lesions evaluated by dermoscopy, researchers correlated histological diagnosis with frequency of occurrence of certain features, however, no algorithm was able to be formed that could accurately predict whether a lesion was a confirmed lentigo maligna or actinic keratosis.1

Another noninvasive tool for the management of facial pigmented lesions is reflectance confocal microscopy. In vivo reflectance confocal microscopy is a technique that relies upon the different refractive indices of light to differentiate cells seen from the optical sectioning and imaging of skin, which can be obtained in minutes depending upon the number of sections imaged.5 Cellular resolution is maintained as skin is imaged to a maximum depth of 200Ìm, which can include superficial layers of the dermis in its imaging field.3,6 A study evaluating 28 lichen planus-like keratoses (LPLKs) with RCM found a correlation between RCM features and histopathology. The honeycomb pattern of the spinous layer found in 78.6 percent of LPLKs correlated to the spinous-granular layer without specific atypia of keratinocytes histologically, while elongated bulbs and/or bulbous projections at the dermo-epidermal junction in 75 percent of LPLKs on RCM correlated with elongated bulbous rete ridges histologically. Other features noted included the presence of numerous plump bright cells and/or bright stellate spots in the superficial dermis in 92.9 percent of RCM images of LPLK, which corresponded to the infiltration of melanophages and lymphocytes in the superficial dermis.7

Combining current noninvasive techniques, such as dermoscopy and reflectance confocal microscopy, with traditional methods can provide an optimum level of care for patients with lesions on the face. Additional uses of noninvasive imaging techniques include initial evaluation of lesions prior to more invasive procedures and also as a tool to determine the degree of treatment needed.6 When used for the imaging of a suspected LPLK, RCM specifically allows for a horizontal view of a lesion in its entirety so that any cancerous lesion contiguous with the LPLK can also be detected.6,7

RCM, however, does have its limitations. The most concerning of these involves the depth of imaging; RCM imaging cannot be done farther than a depth of 200 Ìm, leaving any lesions present beyond this area undiagnosed.3,6,8 In addition, interpretation of RCM images requires training for most clinicians. However, studies have shown that even minimal training can greatly increase diagnostic accuracy. In a study conducted in 2005, five independent readers were given a thirty minute instructive course about the evaluation of confocal images, and then instructed to classify 117 melanocytic skin lesions. Overall sensitivity and specificity were 88.15% and 97.60% respectively. Despite their drawbacks, noninvasive imaging tools along with traditional histology can guide dermatologists in determining the degree of treatment needed and lead to a more cosmetically acceptable outcome.

Conclusion

We report a case (see sidebar) in which RCM aided in both the diagnosis and management of a prominent facial pigmented lesion. The use of dermoscopy and confocal microscopy followed by a superficial scrape biopsy for confirmation allowed for optimum treatment in an area that showed aesthetic sensitivity and shielded the patient from unnecessary facial scarring. In addition, past research has indicated that the use of confocal microscopy enhances diagnostic accuracy particularly of skin cancer when used in conjunction with dermoscopy.3 With much research emerging on the benefits of noninvasive imaging as a diagnostic tool, clinicians should consider its use as a primary tool in the management of suspicious lesions —particularly those in which routine biopsy is not feasible.

Cindy Wassef and Rosa Mateus MD have no financial disclosures or conflicts of interest. Dr. Rao is a consultant for Lucid Inc. and the nature of compensation is equipment.

Cindy Wassef, BA is a medical student a UMDNJ-New Jersey Medical School.

Rosa Mateus, MD is a research fellow at Rao Dermatology.

Babar K. Rao, MD is Associate Clinical Professor of Dermatology at UMDNJ-Robert Wood Johnson Medical School.