Melanoma of the palms, also referred to as acral melanoma, is an uncommon but high-risk type of skin cancer. The unique skin structure and pigmentation patterns of the palms make diagnostic assessment more complex compared with other body sites.

As a skin cancer screening practitioner, the use of structured diagnostic algorithms combined with distributive dermoscopy terminology allows accurate assessment and improves the likelihood of early detection.

Why the Palms Require Special Attention

Palmar skin is glabrous, meaning it lacks hair follicles and sebaceous glands. The dermoscopic patterns seen on this surface differ substantially from those on the rest of the body. Instead of networks or reticular pigment, the hallmark dermoscopic features on the palms are distributed along the dermatoglyphics – the ridges and furrows that form fingerprints and palm lines.

These same principles also apply to the soles of the feet; however, for the purpose of this blog we are focusing specifically on the palms of the hands. Recognising these site-specific features is essential when applying diagnostic algorithms.

Key Dermoscopy Terminology on Palms

When assessing pigmented lesions on the palms, the following distributive dermoscopy descriptors are most relevant:

• Parallel ridge pattern – pigment aligned along the ridges of the dermatoglyphics.
  
  
• Parallel furrow pattern – pigment aligned within the furrows between ridges.
  
  
• Lattice-like pattern – pigment showing a criss-cross or checkerboard configuration along both ridges and furrows.
  
  
• Fibrillar pattern – pigment appearing as fine, oblique streaks across the ridges and furrows.
  
  

Stepwise Diagnostic Algorithms

Several structured diagnostic algorithms have been developed specifically for acral sites. The aim is to increase diagnostic accuracy while minimising unnecessary biopsies.

1. The Parallel Ridge Algorithm

• Lesions showing pigment predominantly on the ridges should be regarded as suspicious.
  
  
• Any lesion with a clear parallel ridge distribution should be considered for biopsy or referral for further evaluation.
  
  
• Conversely, pigment restricted to the furrows is usually benign, particularly if the distribution is symmetrical.
  
  

2. BRAAFF Algorithm

BRAAFF stands for Blotch, Ridge pattern, Asymmetry of structures, Asymmetry of colours, Furrow pattern.

• +1 point for each: irregular blotch, parallel ridge pattern, asymmetry of structures, asymmetry of colours.
  
  
• –1 point for a parallel furrow pattern.
  
  

A total score of ≥1 supports suspicion for melanoma. This algorithm combines both positive and negative indicators, improving specificity when screening.

3. Revised 3-Step Algorithm

This method begins by determining whether a lesion has a typical benign pattern (parallel furrow, lattice, or fibrillar).

• If yes, the lesion can be monitored.
  
  
• If no, and especially if a ridge pattern or irregular distribution is present, the lesion is classified as suspicious.
  
  

The emphasis is on excluding clearly benign patterns first, then applying a higher threshold of suspicion for atypical features.

4. Chaos and Clues (Prof. Cliff Rosendahl)

Another useful framework is the Chaos and Clues algorithm developed by Professor Cliff Rosendahl. This approach can be applied broadly to pigmented lesions, including those on the palms.

• Chaos is defined as asymmetry in structure or colour. If chaos is absent, the lesion is usually benign.
  
  
• If chaos is present, the practitioner actively looks for clues to malignancy. On the palms, relevant clues include the parallel ridge pattern, irregular dots or clods, multiple colours, or an atypical blotch.
  
  
• The presence of chaos plus one or more clues increases the suspicion for melanoma and supports excision or further management.
  
  

Practical Considerations in Screening

When applying these algorithms, it is important to consider lesion size, symmetry, and homogeneity of colour distribution:

• Asymmetry in either pigment distribution or colour is concerning.
  
  
• Multicolour presentation (brown, black, grey, or blue in a single lesion) increases the index of suspicion.
  
  
• Changing lesions, particularly new or enlarging pigmented macules on the palms, require prompt evaluation.
  
  

Recording dermoscopic images during screening allows comparison over time and assists in detecting early changes.

The Role of the Skin Cancer Screening Practitioner

For individuals at risk, especially those with darker skin types or extensive sun exposure histories, screening of the palms is often overlooked. As a skin cancer screening practitioner, part of the role is to ensure these areas are assessed thoroughly during routine full-skin examinations.

By applying distributive dermoscopy terminology and structured diagnostic algorithms, including the Chaos and Clues method, the practitioner can detect lesions that warrant early intervention.

Conclusion

Melanoma on the palms poses a diagnostic challenge due to unique site-specific patterns. However, by using distributive dermoscopy terminology – focusing on ridge, furrow, lattice, and fibrillar distributions – and applying structured diagnostic algorithms such as the Parallel Ridge Rule, BRAAFF, the Revised 3-Step Algorithm, and Professor Rosendahl’s Chaos and Clues, accurate and early recognition is achievable.

As a skin cancer screening practitioner, incorporating these tools into everyday assessments can make a significant difference in improving patient outcomes.