Difficult-to-diagnose facial melanomas: Utility of reflectance confocal microscopy in uncovering the diagnosis

LM: Lentigo maligna pAK: pigmented actinic keratosis RCM: reflectance confocal microscopy M elanoma on sun-damaged skin, commonly known as lentigo maligna (LM, akin to melanoma in situ) and lentigo maligna melanoma (akin to invasive melanoma), is mostly found on the head and neck of elderly patients. This type of melanoma, particularly when found early, may be difficult to diagnose on clinical inspection. Dermoscopy is a noninvasive imaging technique that aids in the identification of pigmented skin lesions and increases the diagnostic accuracy beyond naked eye examination. The dermoscopic criteria for facial LM were previously described. Because facial skin is characterized histopathologically by prominent adnexal openings, solar elastosis, and flattening of the dermoepidermal junction, the dermoscopic criteria of LM are distinct from those used for melanomas on the body and extremities. Moreover, the dermoscopic differentiation between facial LM and other nonmelanocytic diagnostic entities, such as pigmented actinic keratosis (pAK), solar lentigo, or lichen-planuselike keratosis can be challenging. In daily practice, when presented with a pigmented facial macule, the clinician must decide whether to biopsy the lesion and possibly leave a scar at a cosmetically sensitive site, followupwith the lesion, or treat it with nonsurgical modalities (eg, cryotherapy and topical creams). This decision may be hampered by some degree of diagnostic uncertainty. To aid in such a scenario, reflectance confocal microscopy (RCM) is a diagnostic device that uses a low-intensity laser light to produce high-resolution