Color variation of melanin depends on its location in the skin. In the stratum corneum and upper epidermis, melanin is jet black (appearing dermoscopically as dark spots); in the basal layer and dermoepidermal junction, it is brown (brown globules); in the papillary dermis it is blue-gray; and in the reticular dermis it is steel blue (blue nevus). Due to the Tyndall effect, in which short-wavelength visible light (blue) is dispersed and reflected more than long-wavelength light (red), the blue color of otherwise black melanin is explained by the depth of the pigment deep in the dermis. The dermoscopic image of a blue nevus in Figure 1A shows color perspective with change in color to blue and fading color intensity (pale blue) due to the Tyndall effect. The histopathologic image in Figure1B shows melanocytes deep in the dermis.
Thank you for submitting a comment on this article. It will be reviewed by JAMA Dermatology editors. You will be notified when your comment has been published. Comments should not exceed 500 words of text and 10 references.
Do not submit personal medical questions or information that could identify a specific patient, questions about a particular case, or general inquiries to an author. Only content that has not been published, posted, or submitted elsewhere should be submitted. By submitting this Comment, you and any coauthors transfer copyright to the journal if your Comment is posted.
* = Required Field
Disclosure of Any Conflicts of Interest*
Indicate all relevant conflicts of interest of each author below, including all relevant financial interests, activities, and relationships within the past 3 years including, but not limited to, employment, affiliation, grants or funding, consultancies, honoraria or payment, speakers’ bureaus, stock ownership or options, expert testimony, royalties, donation of medical equipment, or patents planned, pending, or issued. If all authors have none, check "No potential conflicts or relevant financial interests" in the box below. Please also indicate any funding received in support of this work. The information will be posted with your response.
Some tools below are only available to our subscribers or users with an online account.
Download citation file:
Web of Science® Times Cited: 6
Customize your page view by dragging & repositioning the boxes below.
More Listings atJAMACareerCenter.com >
The Rational Clinical Examination: Evidence-Based Clinical Diagnosis
All results at
Enter your username and email address. We'll send you a link to reset your password.
Enter your username and email address. We'll send instructions on how to reset your password to the email address we have on record.
Athens and Shibboleth are access management services that provide single sign-on to protected resources. They replace the multiple user names and passwords necessary to access subscription-based content with a single user name and password that can be entered once per session. It operates independently of a user's location or IP address. If your institution uses Athens or Shibboleth authentication, please contact your site administrator to receive your user name and password.