Many parents, when washing their baby’s hair, will notice a patch of skin that looks different – yellowish in color, feels a bit thick, and no hair grows on it. Sometimes similar yellow patches can also be found on the body, which could be a sebaceous nevus.
Unlike red vascular birthmarks and pigmented birthmarks like café-au-lait spots, this special yellow birthmark poses a certain risk of malignant transformation, often causing parents to be extremely anxious. This article today aims to alleviate anxiety and clarify everything at once.
What does a sebaceous nevus look like?
Sebaceous nevi are usually present at birth or shortly after birth, and are mostly single.
Location: Most commonly found on the scalp and neck.
Color: Usually light yellow, light brown, slightly darker than the surrounding skin.
Texture: It feels a bit rough, thick, like a small piece of “hard skin” is attached, the surface may be flat or slightly raised.
Light brown, located on the face
Light yellow, located on the scalp
Sebaceous nevi on the scalp often have no hair growth, making them relatively easy to spot.
As the baby grows, it will also gradually grow along, but will not suddenly increase in size. However, during puberty, affected by the fluctuations in sex hormone levels, sebaceous nevi often proliferate, especially on the scalp, becoming more uneven, rougher, and in professional terms, “verrucous hyperplasia”.
How is it usually diagnosed?
Most sebaceous nevi are diagnosed through clinical presentation, in layman’s terms, the doctor takes a look and sometimes a touch, and can make a relatively certain diagnosis. However, “yellow birthmarks” could also be other possibilities, such ascongenital skin dysplasia, verrucous nevus, mastocytoma, etc. Generally, the doctor will assess through a face-to-face consultation, and further examinations, such as histopathology, may be needed for unclear cases.
What is the cause of sebaceous nevus?
Is this birthmark due to something the mother shouldn’t have eaten during pregnancy? Or is it because the baby bumped their head or pulled their hair when they were little?
Neither
, sebaceous nevi are generally sebaceous gland malformations, belonging to benign skin hamartomas,
related to genetic mutations in local tissues
.
Its occurrence is a probabilistic event, having nothing to do with diet during pregnancy. It also has no association with hair pulling or trauma; any perceived connection is likely coincidental. When the baby is born, the hair is sparse, and the small yellow patches on the scalp are not very noticeable. Later, as the surrounding hair grows, the “yellow birthmark” becomes visible.
What should I do if I find a sebaceous nevus?
Sebaceous nevi are composed of the epidermis, hair follicles, sebaceous glands, and apocrine sweat glands, and are benign skin structures. If the skin lesion is stable, it does not need to be treated immediately and can be observed.
Some parents may ask, “Why does the doctor suggest removing this yellow birthmark when I go to the hospital? Isn’t it benign? Is this overtreatment?” It’s not really.
Concern about sebaceous nevus-associated tumors
Sebaceous nevi are like fertile land, prone to “growing other things,” especially appendageal tumors. But parents shouldn’t worry, the general probability of “growing things” is more common in adults, the probability of sebaceous nevus-associated tumors under 18 is 1.7%, which is very low.
Sebaceous nevi are often associated with benign skin tumors
, such as syringocystadenoma papilliferum, trichoblastoma, etc.
Occasionally there may be malignant tumors, such as basal cell carcinoma, etc., but the rate of cancer occurrence is less than 1%.
Dermatologists often worry about sebaceous nevus-associated tumors and perform excision.
Concern about affecting aesthetics
Moreover, sebaceous nevi are prone to occur on the head and neck, and over time, they can become verrucous and affect aesthetics. Some patients cannot tolerate this and choose to have them removed.
Therefore, many people choose to remove the sebaceous nevus before it develops into verrucous hyperplasia, as the scar from the removal is relatively better in terms of recovery.
For sebaceous nevi on the scalp, changes are often not easily observed (hidden in the hair), and removal can prevent hidden secondary tumor changes from going unnoticed.
If the following situations occur, treatment is still recommended:
● Affecting aesthetics;
● Rapid growth;
● Nodules, nodules, ulcers, or recurrent redness, inflammation on the sebaceous nevus.
Currently, the most effective treatment is surgical excision, in simple terms, it means removing this special piece of skin and stitching up the surrounding normal skin.
Why are laser and cryotherapy not recommended?
Because the “root” of the sebaceous nevus is relatively deep (excision needs to reach the fat layer), laser and cryotherapy may not be able to clear it completely, easily recurring, and repeated stimulation is not good.
Do I need to remove it immediately?
I’m scared now, is the sebaceous nevus like a time bomb, do I need to remove it immediately?
This is the question parents are most concerned about. As mentioned earlier, the probability of malignant transformation of sebaceous nevi is very low, less than 1%, and mostly occurs in adulthood. Sebaceous nevi in infancy and childhood are usually in a static state, very stable and unchanged, and do not need to be removed if there are significant changes.
Signs of malignancy include “sudden enlargement, nodules, ulceration, bleeding,” etc., as long as they are dealt with in time, the risk is basically controllable. So there is no need to be too anxious after finding it, just regularly review and remove it in time.
When is the best time to remove it?
The timing of removal is also a point of considerable debate among doctors. Some scholars have statistically analyzed 62 cases of scalp sebaceous nevus removal in a single-center study, comparing the incidence of adverse reactions such as hypertrophic scarring, hair loss, and scar widening in the pediatric group and the adult group, and found that the incidence in the pediatric group (28.1%) is higher than in adults (6.7%), therefore it is suggested that it is better to remove scalp sebaceous nevi after adulthood.
However, it should be said that although the scar formed after the removal of sebaceous nevi may affect local hair growth, doctors will try to operate meticulously to reduce the impact on hair follicles. Moreover, most sebaceous nevi are hairless, so even if there is a scar affecting hair growth after removal, it is smaller than the original area that did not grow hair.
Some scholars believe that sebaceous nevus removal should be performed in infancy because the skin lesion is relatively small at this time, and scar management is more ideal, but the tolerance of local and general anesthesia in babies should also be considered.
The choice of when to remove it depends on the location and size (of the lesion, one-time/staged removal), whether there is enlargement or thickening, and tendency towards malignancy. Most surgeons opt for removal before the expansion during puberty, as the tolerance for anesthesia and surgical cooperation is good at this time, rather than observing until symptoms appear and then removing. The specific situation needs specific analysis, and when you are unsure, you might as well consult a professional dermatologist and surgeon.
Summary
Finally, here is a summary: Sebaceous nevi are a benign skin condition that babies are born with, which can be understood as a yellow birthmark with a very low probability of malignant transformation. The method of removal is surgical excision. Stable skin rashes can be observed first, and medical attention should be sought in a timely manner if abnormalities are found. If parents are unsure, they can take their baby to a dermatologist for a more reassuring assessment.
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