Stable slate gray to blue lesions that are asymptomatic raise the possibility of a blue nevus, also known as dermal dendritic melanocytic proliferations. In this case, dermoscopy confirmed a uniform dark color with no signs suggestive of melanoma or pigmented basal cell carcinoma (BCC).
Blue nevi are the result of a benign localized proliferation of dermal dendritic melanocytes. The blue color is due to the increased pigment deep in the dermis that reflects the blue shorter wavelength light while absorbing longer wavelengths.1 In this author’s experience, these “blue” lesions usually appear to be more gray (as was the case with this individual). Dermoscopy shows a steel blue homogenous pigmentation.2
It is helpful to use dermoscopy to screen for an atypical pigment network, regression of pigmentation, or abnormal pigmentation; these are signs of atypical nevi and melanoma. It is also important to look for arborizing blood vessels and leaf-like structures that can be seen in pigmented BCCs. Both melanoma and pigmented BCCs can appear as circumscribed dark lesions.
Reassuring factors for blue nevi are lesions that are stable in size and color over time, asymptomatic, and have not bled nor shown signs of erosion. If the diagnosis is in doubt, excise the lesion in its entirety for definitive pathology. Since the melanocytes are typically deeper in blue nevi than in most other nevi, a deep shave technique may not remove the lesion in its entirety. A deeper than usual shave (or, if feasible, a full-thickness excision) may return better results with quicker healing.
This patient was advised of the benign nature of a blue nevus. He was counseled to watch for any changes in the lesion and to return for reevaluation if symptoms or changes occurred.
Image and text courtesy of Daniel Stulberg, MD, FAAFP, Professor and Chair, Department of Family and Community Medicine, Western Michigan University Homer Stryker, MD School of Medicine, Kalamazoo.