Anatomy of palms and soles
The unique appearance of the skin on palms and soles is due to the presence of alternating furrows and ridges, which are responsible for creating our individualized dermatoglyphic patterns (fingerprints) The location of pigment in relationship to the furrows and ridges can help in differentiating benign nevi from melanoma. Dermoscopy helps more precisely localize the pigment and has been shownmto significantly improve the observer’s diagnostic accuracy when evaluating volar melanocytic tumors. Numerous specific dermoscopic patterns have been defined for nevi and melanoma located on acral sites. In benign melanocytic tumors, the location of the pigment tends to favor the crista limitans, which corresponds to the furrows of the skin. Recentresearch has revealed that acral nevi may be located at he tips of rete ridge sassociated with the crista intermedia and limitans; however, they preferentially transfer melanin to the keratinocytes associated with the furrow. In melanoma the malignant melanocytes tend to cluster around the crista intermedia, which in turn often results in pigment located on the ridges. Lesions on volar skin that manifest any of the melanoma-specific structures (malignant patterns).
Parallel furrow pattern
Linear pigmentation, predominantly localized to the furrows. The ridges are relatively hypopigmented.
Similar to the parallel furrow pattern with the addition of parallel pigment bands that cross over the ridges from one furrow to the next.Pattern can chow some dots
Dense fibrillar pigmentation composed of multiple thin parallel lines that cross both the furrows and ridges; the lines have a transverse orientation in relation to the furrows and ridges
Malignant dermoscopy pattern
Parallel ridge pattern
Linear pigmentation of the ridges. The furrows are relatively hypopogmented.
Diffuse pigmentation of variable shades of brown
Diffuse pigmentation of different shades of brown color not respecting furrows or ridges.
Combination of many pigmentation patterns (multicomponent pattern)
Atypical fibrillar pattern
A fibrillar pattern that is very heterogeneous, that is asscociated with another malignant pattern, or that is not located on the areas of the foot bearing the body pressure is called atypical fibrillar pattern. This should be considered with precaution.
Milky red areas
Presence of reddish whitish colors. This is mainly seen in thick tumors when there is a nodular component which is vascularized. Most of the time this part is raised or even nodular and and associated with a multicomponent pattern.
This alrogithm has been proposed recently by Lallas et al. 
B Irregular Blotch +1
R Parallel Ridge Pattern +3
A Asymmetry of Structures +1
A Asymetry of colors +1
F Parallel Furrow Pattern -1
F Fibrillar Pattern -1
1 point is required to make the diagnosis of melanoma.
- Braun et al.: Dermoscopy of acral melanoma: a multicenter study on behalf of the international dermoscopy society. Dermatology (Basel) 2013;227:373-80. PMID: 24296632. DOI.
- Phan et al.: Dermoscopic features of acral lentiginous melanoma in a large series of 110 cases in a white population. Br. J. Dermatol. 2010;162:765-71. PMID: 19922528. DOI.
- Lallas et al.: The BRAAFF checklist: a new dermoscopic algorithm for diagnosing acral melanoma. Br. J. Dermatol. 2015;173:1041-9. PMID: 26211689. DOI.