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- Presentation
Dermoscopy of Acral Melanocytic Lesions: Volar Skin Patterns, Algorithm, and Melanoma Indicators
Description
The lecture explains dermoscopy of acral melanocytic lesions on palms and soles, emphasizing volar skin anatomy and the relationship between skin ridges, furrows, and eccrine openings. This anatomy underlies the key dermoscopic algorithm: lesions showing melanoma-associated patterns should be biopsied, while benign patterns can often be reassured or monitored. The strongest melanoma indicator is the parallel ridge pattern, where pigment is confined to the ridges; this is seen in most acral melanomas and is rare in acral nevi. Other concerning patterns include irregular diffuse pigmentation, multiple shades of brown/blue/black, and multi-component patterns. Important mimickers of parallel ridge pattern include benign conditions such as lentigines, volar melanotic macules, exogenous dyes, chemotherapy pigmentation, congenital nevi, and subcorneal hemorrhage, which can often be distinguished by clinical context, symmetry, lack of malignant features, or clearing with scraping. Benign acral nevi most commonly show parallel furrow and lattice patterns, and the lecture also reviews the fibrillar pattern, which may be benign if regular but concerning if irregular, especially on non-weight-bearing or palmar skin. Less specific patterns such as globular, homogeneous, reticular, and non-typical lesions are discussed as usually benign but sometimes requiring monitoring or biopsy depending on size, irregularity, and context. Overall, the lecture reinforces that parallel ridge pattern is the strongest predictor of acral melanoma, while parallel furrow and lattice patterns favor benign nevi.
View moreConclusions
- On acral volar skin, dermoscopy can reliably separate many benign from malignant melanocytic lesions by using the location of pigment relative to ridges and furrows.
- The parallel ridge pattern is the strongest dermoscopic predictor of acral lentiginous melanoma and should usually prompt biopsy.
- Irregular diffuse pigmentation and multicomponent patterns are also strongly associated with acral melanoma and are concerning findings.
- Parallel furrow and lattice patterns are the most reassuring dermoscopic patterns and most often indicate benign acral nevi.
- Fibrillar patterns require caution because regular fibrillar patterns are usually benign on weight-bearing skin, but irregular or non-weight-bearing fibrillar patterns may represent melanoma.
- Oblique dermoscopy or horizontal pressure can help distinguish a benign regular fibrillar pattern from an irregular fibrillar or ridge-based malignant pattern.
- Some lesions that mimic melanoma patterns, such as volar melanotic macules, subcorneal hemorrhage, congenital nevi, and certain syndromic or drug-related pigmentations, can be recognized by clinical context and specific clues.
- When a lesion does not fit a typical benign acral pattern and is larger than 7 mm, biopsy is generally recommended, while smaller atypical lesions may be monitored.
- Overall, the revised algorithm reinforces that pattern recognition plus lesion size and anatomic context improves diagnostic accuracy for acral melanocytic lesions.
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