Dermoscopy of Facial Lesions: Lentigo Maligna and Solar Lentigo

Overview / DefinitionLentigo maligna is a type of melanoma in situ that typically arises on sun-damaged skin, often presenting as a large, irregularly pigmented lesion. In contrast, solar lentigo is a benign hyperpigmentation resulting from chronic sun exposure, characterized by a uniform color and well-defined borders. EpidemiologyLentigo maligna is more common in older adults, particularly those with fair skin who have a history of significant sun exposure. It is often seen in sun-damaged areas, such as the face and neck, with a higher incidence in individuals over 60 years of age. Solar lentigo, commonly referred to as age spots or liver spots, is prevalent among older populations, especially in individuals with a history of excessive UV exposure. Pathophysiology / MechanismThe pathophysiology of lentigo maligna involves the proliferation of melanocytes in the epidermis, typically associated with mutations caused by UV irradiation. This proliferation can lead to the dysplastic features seen in dermoscopy. Solar lentigo results from the accumulation of melanin due to increased melanocyte activity in response to UV exposure, leading to a benign increase in pigmentation. Clinical PresentationLentigo maligna usually presents as a large, asymmetrical, irregularly bordered macule, with varying shades of brown and black, often accompanied by a scaly surface. In contrast, solar lentigo presents as smaller, well-defined, uniformly pigmented brown macules, typically on sun-exposed areas like the face, back of the hands, and forearms. Lentigo maligna: asymmetrical, irregular borders, heterogeneous pigmentation Solar lentigo: symmetrical, uniform color, well-defined borders Diagnosis / WorkupDermoscopy is essential for differentiating between lentigo maligna and solar lentigo. Key dermoscopic features include: Lentigo maligna: atypical network, grey-blue areas, streaks, and a lack of a prominent pigment network Solar lentigo: regular, reticular pigment network, homogeneous p