Moles With a Risk of Cancer: Often Discovered While Washing Your Hair
Skin & BeautyUnderstanding sebaceous nevi - yellow birthmarks on the scalp that carry a small cancer risk, when to remove them, and why surgical excision is the recommended treatment.
Moles With a Risk of Cancer: Often Discovered While Washing Your Hair
Some parents discover a yellow, slightly rough patch on their baby's scalp — often noticed while washing hair. This is likely a sebaceous nevus, a type of birthmark that deserves attention due to its small but real risk of developing tumors over time.
What is a Sebaceous Nevus?
Sebaceous nevi are usually present at birth or shortly after, and are mostly single. They are most commonly found on the scalp and neck. The color is usually light yellow or light brown, slightly darker than surrounding skin. The texture feels rough and thick, like a small piece of 'hard skin' — the surface may be flat or slightly raised.
Sebaceous nevi on the scalp often have no hair growth, making them relatively easy to spot. As the baby grows, the nevus will gradually grow along, but will not suddenly increase in size. However, during puberty, affected by sex hormone fluctuations, sebaceous nevi often proliferate, becoming more uneven and rougher (verrucous hyperplasia).
How is it Diagnosed?
Most sebaceous nevi are diagnosed through clinical presentation — the doctor takes a look and sometimes a touch, and can make a relatively certain diagnosis. However, other possibilities (congenital skin dysplasia, verrucous nevus, mastocytoma) may need to be ruled out, sometimes requiring histopathology.