Dermoscopic Diagnosis of Melanoma on the Face and Acral Skin

Conclusions

• On the face, melanoma diagnosis by dermoscopy depends on recognizing follicular-based patterns rather than the classic pigment network used on trunk and extremities.
• Gray dots are a useful clue for lentigo maligna, but they are not specific because they can also appear in pigmented actinic keratosis, lichen planus-like keratosis, and lentigines.
• The most concerning facial signs are asymmetric follicular openings, rhomboidal or angulated structures, and homogeneous blotches that progressively replace or obliterate follicles.
• Facial melanoma is often suggested by a lesion that stands out as a solitary ‘lone ranger’ among otherwise unremarkable surrounding skin.
• Multiple dermoscopic features may coexist in the same facial melanoma, so the entire lesion must be assessed rather than focusing on only one area.
• Pigmented actinic keratoses can closely mimic lentigo maligna, making dermoscopic distinction difficult in some cases.
• Because facial melanoma can be subtle, dermoscopy is best used to guide targeted biopsy of the most suspicious area rather than always removing the whole lesion first.
• On acral skin, pigment on the ridges is the key warning sign for melanoma, whereas pigment in the furrows usually indicates a benign nevus.
• The parallel ridge pattern is the most specific early dermoscopic sign of acral melanoma and generally warrants biopsy.
• If a non-ridge acral lesion shows a typical benign pattern such as parallel furrow, lattice-like, or fibrillar, it is usually reassuring.
• When acral lesions are non-typical, additional melanoma-specific structures and size thresholds help decide between biopsy and short-interval follow-up.
• Acral melanomas can develop additional conventional melanoma features as they become more advanced, so early recognition is important.
• Several lesions can mimic acral melanoma, including subcorneal hemorrhage, exogenous pigment, drug-related pigmentation, and some congenital acral nevi.
• In acral lesions, a positive paring or scratch test supports subcorneal hemorrhage rather than melanoma.
• In skin of color, standard acral algorithms may be less predictive, so lesion size and evolution become especially important.
• Congenital acral nevi have their own benign patterns, such as crista dotted and peas-in-a-pod, and they may change over time without implying malignancy.
• Pediatric acral melanoma is rare, so history and longitudinal change are especially important before biopsying congenital acral lesions.
• Overall, the presentations emphasize pattern recognition plus clinical context to decide when facial or acral pigmented lesions should be biopsied versus observed.