Read between the lines.
Dr. Lindsey Zubritsky, a board-certified dermatologist based in Mississippi, is “begging” her 1.4 million TikTok followers to check their nails for a vertical line, which could indicate a subungual melanoma, a rare, but serious type of skin cancer.
“If you have a dark-pigmented vertical streak going down your nail, this absolutely should be checked,” Zubritsky said in a 48-second clip that’s drawn 35,300 views since it was posted Tuesday.
“It could potentially be a very serious form of skin cancer called a subungual melanoma,” she added. “While it’s not common, it can be easily missed if you don’t know what you’re looking for.”
Subungual melanomas account for only 0.7% to 3.5% of all malignant melanomas worldwide. A patient’s survival chances depend on the stage of cancer at diagnosis and how far it’s spread.
The exact cause of subungual melanomas is not known, but it doesn’t seem to be linked to sun exposure. Having certain characteristics, including an age between 50 to 70, darker skin, and a family history of melanoma, put people at greater risk.
Subungual melanomas tend to affect the big toe and thumb the most, but it can occur on any finger or toe.
The melanoma appears as a brown-black discoloration of the nail bed, with Verywell Health reporting it’s often misdiagnosed as a fungal infection.
Zubritsky pointed out that not all dark streaks on nails are subungual melanomas — or dangerous.
A longitudinal melanonychia, for example, is a brown or black vertical nail streak that’s typically benign.
“It’s more likely that you have the benign streak. It’s a lighter streak. It’s not changing. It’s found on multiple nails,” Zubritsky explained.
Zubritsky also drew the distinction between a subungual melanoma and a subungual hematoma, which is when blood pools under the nail after a trauma like getting a finger caught in a door or accidentally hitting it with a hammer. Hematomas typically grow out over time.
Finally, Zubritsky advises seeking medical help if you have Hutchinson’s sign, which is “discoloration or a pigment that’s starting to creep up [from the nail] into the skin.” It could be evidence of a subungual melanoma.
