Vitiligo, a relatively common autoimmune skin disorder often passed down in families, affects around 2% of the global population.
Although not contagious or life-threatening, the symptoms include depigmented or milky-white patches on the skin. As it turned out, there’s another unusual sign of vitiligo, which someone noticed when he shone a UV light on his fiancée’s finger.
As reported in a Reddit post by AllPurposeGrunt, the woman had a small, glowing dot on her finger that only appeared under UV light.
AllPurposegrunt shared a picture of the phenomenon, captioned only, “My fiance has a spot that glows green under UV light,” and later shared a video demonstrating that the dot was on his finger and projected onto it from elsewhere.
Intrigued by the mystery, one funny comment said, “The question is, have you checked her entire body? If there are other dots, connect them to discover the hidden picture,” another added, “Alien implanted chip.”
AllPurposeGrunt explained in the comments, “We only noticed it because we were checking out her opals under UV for fun. As one does. 😂.”
Ringworm a potential culprit
Another possible culprit is ringworm, as certain species can produce green or yellow-green fluorescence when examined under a Wood’s lamp, a handheld ultraviolet light used in dermatology. Someone suggested this in the comments, asking, “Is it itchy?” — another sign of a ringworm infection. Grunt responded, “It’s not itchy at all or discolored under normal light.”
Finally, another comment chimed in, “Vitiligo? can glow like that under blacklight, very hard to see on light skin sometimes, especially on the fingers.”
Vitiligo can cause skin to glow
While it’s unclear if AllPurposeGrunt sought an official diagnosis, one sign of vitiligo is that it can indeed cause patches of skin to appear bright or “glow” blue-white under ultraviolet light. It’s one way dermatologists diagnose the disorder.
A follow-up comment said,
Can confirm. I have very pale skin but have some vitiligo patches on my hands. Basically invisible IRL … anyways under black light my hands look like they are cow-patterned 🐄”
For now, it’s a theory, and vitiligo is non-life-threatening. But as Dr. Victor Huang told Dialogues in Dermatology, a leading dermatology podcast from the American Academy of Dermatology, ” … vitiligo is not just a cosmetic disorder, it is truly a medical disorder that can be impactful on the quality of life of our patients.”
Whether it’s vitiligo, ringworm, or something else, to be sure, someone urged AllPurposeGrunt to “check her body for any other areas on her that glow. check youself too.”
The commenter then urged AllPurposeGrunt to photograph the areas, under ultraviolet light and without, and then see a primary care provider to rule out anything serious.
The comment added, “Continue washing hands and give it time, see if any of the spots change. continue photographing them daily to compare (aim for similar times each day if possible). Could be a chemical residue on her hand, could be infection, could be something else. Best two ways to tell are monitor and get a professional assessment.” AllPurposeGrunt responded, “Will do.”
Published: Mar 20, 2026 05:20 am