Comma vessels are slightly curved vessels that appear to take the shape of a comma. These vessels tend to appear slightly out of focus, as their deeper location within the dermis does not allow for sharp visualization under dermoscopy.
Comma vessels are most commonly associated with dermal nevi. In a study of dermal/ congenital nevi, 66.3% exhibited this vascular pattern, with a PPV of 94% . In another study, comma vessels, when distributed in an organized fashion and when they comprise the predominant observed vessel morphology, are predictive that the lesion in question is not a melanoma . In other words, comma vessels are highly suggestive of benign nevi with dermal nevi being the most common, but they can also be seen in compound nevi.
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