The parallel ridge pattern demonstrated the strongest diagnostic performance for identifying acral lentiginous melanoma, with high specificity but incomplete sensitivity, according to a systematic review and meta-analysis published in JAMA Dermatology.
Researchers analyzed dermoscopic features across 41 studies including 8,845 benign acral nevi and 801 acral lentiginous melanomas. The analysis evaluated which dermoscopic patterns most reliably distinguish malignant from benign acral lesions.
The parallel ridge pattern was observed in 79.6% of melanomas compared with 0.6% of benign acral nevi, corresponding to approximately 80% sensitivity and 99.4% specificity. Multicomponent patterns were also associated with melanoma, occurring in 45.8% of cases compared with 5.0% of nevi, with high specificity but lower sensitivity.
By contrast, the parallel furrow pattern was observed in 51.8% of benign acral nevi compared with 8.9% of melanomas, and the latticelike pattern in 13.0% vs 2.7%, respectively. These features demonstrated high specificity for benign lesions (91.1% for parallel furrow and 97.3% for latticelike patterns), although they were present in a small minority of melanomas.
Importantly, no single dermoscopic feature identified all melanomas, as approximately 20% of acral lentiginous melanomas lacked the parallel ridge pattern.
Other patterns showed limited diagnostic utility. Fibrillar patterns occurred at similar rates in melanoma and benign nevi (19.0% vs 14.9%) and were not statistically associated with malignancy. This finding challenges their traditional classification as reassuring features in the widely used 3-step dermoscopic algorithm.
Taken together, the results support a hierarchical, multi-feature approach to acral lesion evaluation. Lesions demonstrating parallel ridge or multicomponent features should raise suspicion for melanoma, whereas parallel furrow and latticelike patterns are more commonly associated with benign lesions but should be interpreted within the broader clinical context.
These findings also extend the expanded 3-step dermoscopic algorithm by reinforcing the diagnostic value of multicomponent structures while questioning the reliability of fibrillar patterns as benign indicators.
The analysis had several limitations, including heterogeneity in study design, dermoscopic definitions, and clinician interpretation. Many studies were retrospective and conducted at single centers.
Reporting of patient skin type was also limited. Although most studies included racial or ethnic data, only three specifically analyzed dermoscopic findings in patients with darker skin types. Emerging evidence suggests the parallel ridge pattern may occasionally appear in normal acral skin in Black patients, underscoring the need for further research in diverse populations.
The researchers reported no conflicts of interest. The study was supported in part by a National Institutes of Health/National Cancer Institute Cancer Center support grant.
Source: JAMA Dermatology
