Skin doctors warn everyone to be on alert for dark moles that could signal skin cancer, but what about the small white spots many people notice on their arms and legs?
The “reverse freckles” are a benign skin condition called idiopathic guttate hypomelanosis. It’s not a sign of any health problems, but the specks can be unsettling, especially if they appear in large numbers, said Dr. Adam Friedman, professor and interim chair of dermatology at the George Washington School of Medicine and Health Sciences
“This isn’t a dangerous condition from a medical perspective, but it can certainly be a cosmetic [concern],” Friedman told TODAY.
“I’ve seen cases where people are covered in these and it can be extremely disabling from the patient’s perspective.”
What is idiopathic guttate hypomelanosis?
It’s characterized by small round or oval, “porcelain-white” spots that appear on sun-exposed areas of the skin, especially on the forearms and shins. They rarely develop on the face.
The name is a good descriptor of the condition. “Idiopathic” means doctors don't know why it develops, “guttate” means resembling tear drop or dew drop, and “hypomelanosis” means white spots, Friedman said.
“So literally the disease’s name means ‘white spots that happen for reasons we don’t really know,’” he noted.
“Something is going wrong along the pattern of melanin production and that’s why we’re getting a white spot — an area where there is no pigment physically in that location. Once this happens, it’s stagnant, it stays that way. This isn’t something that will come and go.”
IGH is not in any way related to vitiligo, which is an autoimmune disease that can produce extraordinarily broad patches of skin without color.
What causes IGH?
The exact cause is unknown, but factors that seem to be involved include aging, ultraviolet exposure, trauma and genetic factors, according to a review of studies published in the American Journal of Clinical Dermatology.
About 87% of people over the age of 40 have the white spots, researchers found. The lesions usually develop on sun-exposed areas, so UV radiation seems to play a role.
When Friedman sees patients who are covered with IGH, there’s always a strong family history of it, he said.
Who is most affected?
The condition is most commonly seen in older people, especially those with a history of long-term sun exposure, the review of studies noted. The average number of spots per person was 13, but some had more than 100.
In Friedman’s experience, fair-skinned people develop the white spots more often, but darker-skinned individuals are more bothered by them because the contrast in pigmentation is more noticeable. Many people also notice the spots in the summer when they’re more tan.
“The darker your skin, the more disabling, from a cosmetic perspective, this can be,” Friedman said. “The severity of this condition can vary tremendously and the more severe cases can certainly be of considerable concern to the person it’s affecting.”
What is the treatment?
If the spots are psychologically bothersome, the easiest treatment is cosmetic camouflage — or applying a dab of foundation or concealer to the area.
Topical retinoids, topical calcineurin inhibitors, cryotherapy, chemical peels and superficial dermabrasion can be effective in treating the condition, the review of studies noted. These treatments would be considered cosmetic and likely not covered by insurance.
Ultimately, there aren’t many great options so prevention is probably the best medicine, Friedman said.
That means focusing on good sun protection — sunscreen, physical protectants like clothing, avoiding the sun at peak hours and seeking shade — especially if IGH runs in your family.