Dermoscopy of Pigmented Acral Lesions

Overview / Definition Pigmented acral lesions refer to pigmented skin lesions that occur on acral surfaces, which include the palms, soles, and nail beds. Dermoscopy is a non-invasive imaging technique that enhances the visualization of these lesions, allowing dermatologists to discern subtle differences in morphology and pattern that may indicate malignancy. Epidemiology Pigmented acral lesions are particularly significant in populations with darker skin types, where the incidence of acral melanoma is higher compared to non-acral melanoma. Key epidemiological insights include: Incidence of acral melanoma is approximately 2-8% of all melanoma cases in Caucasians but up to 20% in African populations. Higher prevalence in individuals aged 40-70 years. Significant association with sun exposure in non-acral areas, but not in acral sites. Pathophysiology / Mechanism The pathogenesis of pigmented acral lesions involves the proliferation of melanocytes in the epidermis and dermis due to genetic mutations often triggered by UV radiation. The primary mechanisms include: Increased melanin production due to UV exposure leading to hyperpigmentation. Mutations in genes such as BRAF and NRAS that are commonly implicated in melanoma. Influence of environmental and genetic factors in the development of these lesions. Clinical Presentation Clinically, pigmented acral lesions can vary widely in appearance, but certain features are noteworthy: Lesions may be macules, patches, or nodules, exhibiting varying degrees of pigmentation. Common colors include brown, black, or blue-black. Lesions may be asymptomatic or may present with itching or bleeding in cases of melanoma. Diagnosis / Workup Dermoscopy plays a crucial role in the evaluation of acral lesions. The following features may be identified: Parallel ridge pattern: Commonly seen in benign lesions. Asymmetry and irregular borders: Indicative of potential malignancy. Color variation: Multiple colors within the lesion raises suspicio