Re: Nichia 365nm Light offerings
It is hard to make the diagnosis without seeing the fluorescence as it can range from flat dark areas to elevated and pink to dark brown, and is variably itchy. The causative organisms aren't easily cultured. It's not frequently that I'm able to diagnose it with UV light. We'll often treat for it empirically if we've ruled out the other common things that cause similar rashes in similar areas.
Aw, what the heck. I'll post the pic here. It's entirely not person-identifiable, and without me telling you, you can't tell what the heck it is.
The white fragments are lint displaying the fluorescent effects of brighteners in laundry detergent, to make your whites whiter and colors brighter.
(sorry 'bout the blur, it was a handheld 1/8th sec exposure - not the light's fault!)
You're absolutely correct that UV light makes certain skin characteristics show up differently than visible light examination. In dermatology we commonly use UV to look at pigment variation; less often to look for things that have a characteristic fluorescence as in this case.
Many women (and some men) will be familiar with imaging "boxes" that take a UV light image of the facial skin to emphasize solar damage and age-related pigment changes. Most often this is used to peddle "anti-aging" products.
Just a reminder, kids, UV light is carcinogenic, so don't go lighting up your faces, groins, or other parts with your McGizmo UV lights. See the comments in the thread above about protecting your eyes! (And while I'm on my soapbox, please all of y'all, exercise reasonable caution with respect to sunlight exposure, perhaps especially if you're of Irish/Scottish heritage and live in Hawaii.)
). Thanks 
