The color wheel approach
What is the Color Wheel?
The Color Wheel approach is a tool for biopsy decision-making that serves to complement and streamline traditional pattern recognition methods of dermoscopy. Utilizing the clinical and dermoscopic colors of a lesion, as well as the lesion’s clinical history and morphology, helps clinicians to arrive at a narrow differential diagnosis prior to engaging in dermoscopic pattern analysis. This may be particularly useful in the case of early malignant lesions, especially amelanotic melanoma, when dermoscopic patterns may not yet be present.
After taking into consideration patient risk factors and the gross features of the lesion, the 4 steps of the Color Wheel can be used to build a list of possible diagnoses. The 4th step is only taken if malignant lesions remain on the differential list. By that point, the list of possible diagnoses should be quite small, making the dermoscopic examination and pattern analysis much more focused and less daunting, especially for dermoscopy beginners. After going through the steps of the Color Wheel approach, the clinician should be able to confidently make the decision whether to biopsy.
Using the Color Wheel
Step 1: Is the lesion flat or raised?
This step is a component of the clinical examination. It is sometimes appeciated visually, or may require palpating the lesion.
Step 2: What color is the lesion on clinical asssessment?
The Color Wheel gives a high-yield differential diagnosis based on each color seen clinically. The clinical color categories include pink-clear, pale brown, brown-black, and others (yellow, purple, red). Having already determined whether the lesion is flat or raised, one can go through the list of diagnoses considered for a particular clinical color and eliminate the inapplicable choices.
Step 3: What color is the lesion dermoscopically?
Using the respective Color Wheel, we cross-reference the list of possible diagnoses that remain after Step 2 with the list corresponding to the relevant dermoscopic color. The dermoscopic colors considered are red, multicolored, brown, and yellow.
Step 4: Is further elucidation needed to decide whether or not to biopsy?
In the case that the narrowed-down list of differential diagnoses includes malignancy, the lesion should be further analyzed for benign or malignant patterns specific to the diagnoses we are ruling out. Often this can be determined with limited dermoscopic patterns.
In the case of elevated neoplasms of uncertain nature, a biopsy is always indicated as the differential includes advanced, aggressive tumor types. However in uncertain flat lesions without malignant features dermoscopic monitoring can also be an option. This is best achieved with serial dermoscopic imaging.