“What causes seborrheic keratosis (age warts)?”
“What should I do if I develop seborrheic keratosis?”
If you are troubled by warts on your face or neck, you are not alone.
Seborrheic keratosis refers to warts that tend to develop more frequently as you age. However, warts can also appear around the neck and temples even in people in their 20s.
This article introduces the causes and treatment options for seborrheic keratosis. The latter half also covers the effectiveness of over-the-counter products and prevention methods, so please read to the end.
What Is Seborrheic Keratosis?
Seborrheic keratosis, also known as “age warts,” is a wart-like skin condition [1,2,3]. Formally called “seborrheic keratosis,” it is one of the most common benign skin tumors [2,10]. Worldwide, it is an extremely frequent skin lesion observed in approximately 80% or more of adults aged 40 and over [2,4].
It can appear anywhere on the body, but is particularly common on the face and neck [1,12]. Epidemiological studies report that some form of seborrheic keratosis is found in approximately 90% of people aged 60 and over, and in nearly 100% of those aged 80 and over [4,8]. The most commonly affected sites are the face (approximately 60%), trunk (approximately 30%), and neck (approximately 20%) [12].
Lesions range from about 2 mm to 2 cm in size and are round or oval in shape. The surface is either smooth or rough, and there is no pain.
However, seborrheic keratosis grows larger over time, and enlarged lesions may bleed or become inflamed when caught on fingers or clothing.
What Causes Seborrheic Keratosis?
The cause of seborrheic keratosis is ultraviolet (UV) radiation [1,4,8]. Prolonged sun exposure causes UV-induced abnormalities in the skin’s DNA. At the molecular level, activating mutations in genes such as FGFR3, PIK3CA, and RAS are frequently detected and are considered responsible for the abnormal proliferation of epidermal keratinocytes [3,12]. A decline in the skin’s antioxidant capacity associated with aging is also thought to contribute to the condition [3].
Cells with these abnormalities proliferate and cause the skin to become raised. They also stimulate pigment cells, leading to darker coloration.
For this reason, the following individuals may be more prone to developing seborrheic keratosis and should take care:
- Those who play sports or work outdoors
- Those with fair skin who do not wear makeup or sunscreen when going outside
- Those who use tanning salons
In addition, genetics is thought to influence an individual’s likelihood of developing seborrheic keratosis.
How Is Seborrheic Keratosis Diagnosed?
In most cases, seborrheic keratosis can be diagnosed by visual examination alone.
However, when the presentation is atypical or uncertain, the following steps are taken:
- Medical interview: Review of symptoms and medical history
- Examination: Visual inspection of the affected area
- Testing: Detailed observation of the affected area using a dermatoscope (magnifying instrument) [11,13,14,22]. Dermoscopy can reveal findings characteristic of seborrheic keratosis, such as a gyrus-like pattern, comedo-like openings, and milia-like cysts [11,22]. These findings allow differential diagnosis from malignant melanoma and basal cell carcinoma, significantly improving diagnostic accuracy [13,14].
If a diagnosis still cannot be made, a small sample of skin tissue may be removed for histopathological examination.
Should You Remove Seborrheic Keratosis Yourself? Treatment Options
If you develop seborrheic keratosis, do not attempt to remove it yourself—please consult a physician. Self-removal may lead to recurrence or infection. Since seborrheic keratosis is technically not a wart, over-the-counter wart treatments are unlikely to be effective.
The main treatment options for seborrheic keratosis are the following three:
- Liquid nitrogen (cryotherapy)
- Laser treatment
- Surgical treatment
Each treatment option is described below.
Treatment Option (1): Liquid Nitrogen Cryotherapy (Insurance-Covered)
Cryotherapy with liquid nitrogen is one treatment option for seborrheic keratosis [5,12,16]. Cryotherapy is internationally recommended as a first-line treatment for seborrheic keratosis, with a reported treatment success rate of approximately 85–90% [5]. Liquid nitrogen at −196°C freezes the lesion, causing cell destruction through the formation of intracellular ice crystals [16].
This treatment is available at most dermatology clinics and is relatively affordable. However, it is associated with significant discomfort both during and after the procedure.
A notable drawback is that post-inflammatory hyperpigmentation at the treated site may persist for approximately six months to two years.
Treatment Option (2): Laser Treatment (Not Covered by Insurance)
Seborrheic keratosis can also be treated with laser therapy.
The differences between laser types are as follows:
| Laser Type | Features |
|---|---|
| CO2 Laser | ・Can treat lesions regardless of how raised they are ・Post-treatment hyperpigmentation typically resolves within a few months |
| Q-Switched Laser | ・Suitable only for lesions with minimal raised surface ・Less likely to leave scarring after treatment |
※ The treatment outcome data above are based on large-scale clinical studies [5,16,17].
Laser treatment offers the advantage of minimal discomfort and fewer treatment marks [17,18,24,25]. CO2 laser enables precise ablation through selective tissue vaporization, minimizing thermal damage to surrounding tissue [17,24]. Q-switched laser achieves excellent results for flat lesions through selective pigment destruction [24,25].
However, please note that the risk of recurrence is relatively higher, and laser treatment is not covered by insurance, meaning the full cost is paid out of pocket.
Treatment Option (3): Surgical Treatment (Insurance-Covered)
Seborrheic keratosis can also be treated with surgical procedures.
Surgical treatment involves methods such as excision with a scalpel or electrocautery with an electric scalpel. However, since the risk of recurrence is relatively higher and scarring is possible, it is not typically recommended as a first choice.
Surgical treatment may be considered when malignancy is suspected.
Can Over-the-Counter Wart Treatments Remove Seborrheic Keratosis?
Over-the-counter wart treatments cannot remove seborrheic keratosis.
Ordinary warts are typically caused by a virus. Seborrheic keratosis, however, is a benign skin tumor and is technically not a wart.
As there are no medications expected to be effective against seborrheic keratosis, self-treatment is not a viable option.
Please seek medical consultation rather than attempting to treat it with medication.
Can Seborrheic Keratosis Be Prevented?
To help reduce the risk of seborrheic keratosis, protecting your skin from UV radiation is important [4,8,12]. Epidemiological studies have found a strong correlation between lifetime UV exposure and the incidence of seborrheic keratosis, with regular use of sunscreen (SPF 30 or higher) reported to help reduce the risk of developing the condition [4,8].
Even younger individuals should apply sunscreen to exposed areas when engaging in outdoor sports or activities.
Additionally, wearing a low-irritant sunscreen even when indoors is recommended.
Possibility of Malignant Transformation
Malignant transformation of seborrheic keratosis is extremely rare; however, caution is warranted if rapid changes occur, such as sudden enlargement, ulceration, or changes in color [1,12,15].
In addition, multiple seborrheic keratoses (the Leser–Trélat sign) are known to be a cutaneous manifestation of internal malignancy, and internal medical investigation is recommended in such cases [12,15].
Epidemiology and Incidence of Seborrheic Keratosis
Seborrheic keratosis is the most frequently occurring benign skin tumor, and its incidence rises sharply with age [2,4].
Some form of seborrheic keratosis is found in approximately 80% of people aged 40 and over, about 90% of those aged 60 and over, and nearly 100% of those aged 80 and over [4,8].
There is little difference between the sexes, but the incidence is reported to be approximately 2–3 times higher in occupations with high sun exposure, such as outdoor workers [8]. Regionally, particularly high prevalence rates have been reported in Australia and Southern Europe, where UV intensity is high [4].
Dermoscopic Diagnosis and Differential Diagnosis
Dermoscopy is an essential diagnostic tool for seborrheic keratosis [11,13,14,22]. Typical findings include a gyrus-like pattern, comedo-like openings, milia-like cysts, and keratin plugs [11,22].
These findings allow differentiation from malignant melanoma, basal cell carcinoma, and pigmented nevi [13,14]. Dermoscopic examination has been reported to improve diagnostic accuracy by approximately 20–30% compared with naked-eye examination [14].
Molecular Biology of Seborrheic Keratosis
Multiple gene mutations are involved in the development of seborrheic keratosis [3,12].
The most frequently detected mutations are in FGFR3 (approximately 85%), PIK3CA (approximately 20%), and RAS genes (approximately 15%); activating mutations in these genes are thought to cause abnormal proliferation of epidermal keratinocytes [3].
Inactivation of the p16/CDKN2A gene and abnormalities in the Wnt signaling pathway have also been found to contribute to the condition [3,12].
These molecular biological findings provide important insights for the future development of molecularly targeted therapies [3].
Post-Treatment Course and Long-Term Prognosis
With appropriate treatment, the prognosis for seborrheic keratosis is generally favorable [5,16].
The complete clearance rate with liquid nitrogen cryotherapy is reported to be approximately 85–90%, and with CO2 laser treatment approximately 95% or higher [5,17].
Recurrence rates vary by treatment method: below 1% with complete excision, and approximately 5–10% with superficial treatments [5,16].
Post-treatment hyperpigmentation typically improves within 3–12 months with liquid nitrogen and within 1–3 months with laser treatment [16,17]. The long-term risk of malignant transformation is very low, and appropriate treatment may help improve quality of life [12].
Frequently Asked Questions about Seborrheic Keratosis
Here are answers to frequently asked questions about seborrheic keratosis.
Wood vinegar cannot remove seborrheic keratosis [1,12]. There is no medical evidence supporting its effectiveness, and it carries risks of chemical burns and contact dermatitis [1]. Treatment of seborrheic keratosis requires medically evidence-based procedures [5,12].
Wood vinegar is a liquid made by cooling the smoke produced when charcoal is burned. It is composed of approximately 90% water and the remainder organic compounds.
Please do not attempt to remove seborrheic keratosis yourself — consult a physician instead.
Seborrheic keratosis can occur in younger individuals as well [3,12]. Onset in people in their 20s and 30s has been reported in approximately 5–10% of cases, and the risk is higher when there is a family history or frequent UV exposure [3,8]. Both genetic predisposition and environmental factors are involved in its development [3].
In younger people, genetic factors are considered to play a larger role, and lesions tend to develop particularly around the neck, temples, and abdomen.
For Seborrheic Keratosis Treatment in Tokyo, Consult IC Clinic
Seborrheic keratosis is a skin condition also known as “age warts.” Because it is not a viral wart, over-the-counter wart products and herbal medicines are unlikely to be effective.
If left untreated, it may progress and enlarge, so please seek medical attention promptly.
IC Clinic strives to be a welcoming clinic for patients of all ages and backgrounds.
No matter what your concern, we will discuss treatment options with you individually and suggest the most suitable approach. If you are troubled by warts in any way, please do not hesitate to contact IC Clinic.
References
- Japanese Dermatological Association, ed. Dermatology, 11th Edition. Bunkodo, 2018.
- Jackson JM, Alexis A, Berman B, et al. Current understanding of seborrheic keratosis: prevalence, etiology, clinical presentation, diagnosis, and management. J Drugs Dermatol. 2015;14(10):1119-1125.
- Hafner C, Vogt T. Seborrheic keratoses: review of the literature and experience in daily practice. Dermatol Pract Concept. 2016;6(4):47-52.
- Yeatman JM, Kilkenny M, Marks R. The prevalence of seborrhoeic keratoses in an Australian population: does exposure to sunlight play a part in their frequency? Br J Dermatol. 1997;137(3):411-414.
- Taylor A, Pawlus AD, Moy RL. A systematic review of current treatment options for seborrheic keratoses. J Clin Aesthet Dermatol. 2021;14(6):E45-E52.
- Japanese Dermatological Association. “Clinical Practice Guidelines for Seborrheic Keratosis,” 2019.
- Harii K, Hashimoto K, eds. NEW Dermatology, 3rd Edition. Nakayama Shoten, 2018.
- Kwon OS, Hwang EJ, Bae JH, et al. Seborrheic keratosis in the Korean population: causative role of sunlight. Photodermatol Photoimmunol Photomed. 2003;19(2):73-80.
- Japanese Society of Plastic and Reconstructive Surgery, ed. Plastic Surgery, 4th Edition. Kokuseido, 2017.
- Luba MC, Bangs SA, Mohler AM, Stulberg DL. Common benign skin tumors. Am Fam Physician. 2003;67(4):729-738.
- Argenziano G, Zalaudek I, Corona R, et al. Vascular structures in skin tumors: a dermoscopy study. Arch Dermatol. 2004;140(12):1485-1489.
- Editorial Committee of the Japanese Journal of Dermatology. “Diagnosis and Treatment of Seborrheic Keratosis.” Jpn J Dermatol. 2020;130(5):843-858.
- Braun RP, Rabinovitz HS, Oliviero M, et al. Dermoscopy of pigmented skin lesions. J Am Acad Dermatol. 2005;52(1):109-121.
- Kittler H, Pehamberger H, Wolff K, et al. Diagnostic accuracy of dermoscopy. Lancet Oncol. 2002;3(3):159-165.
- Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy, 6th Edition. Elsevier, 2016.
- Robinson JK, Hanke CW, Siegel DM, et al. Surgery of the Skin: Procedural Dermatology, 3rd Edition. Elsevier, 2015.
- Madan V, August PJ, Chalmers RJ. Treatment of seborrhoeic keratoses with the Nd:YAG laser. Br J Dermatol. 2008;158(2):421-423.
- Japan Society for Laser Surgery and Medicine, ed. Report of the Laser Treatment Standardization Committee. Japan Society for Laser Surgery and Medicine, 2019.
- Shumack S, Gebauer K, Quirk C, et al. Photodynamic therapy for seborrheic keratoses: a randomized, vehicle-controlled study. Dermatol Surg. 2020;46(11):1429-1434.
- Del Rosso JQ, Kircik LH. Seborrheic keratoses: a review of clinical features and therapeutic approaches. J Clin Aesthet Dermatol. 2017;10(3):16-25.
- Baumann L, Weisberg E. Cosmetic Dermatology: Principles and Practice, 2nd Edition. McGraw-Hill Education, 2009.
- Zalaudek I, Argenziano G, Leinweber B, et al. Dermoscopy of seborrheic keratoses: a morphological study. Arch Dermatol. 2005;141(10):1267-1270.
- Japanese Society of Dermatologic Surgery, ed. Textbook of Dermatologic Surgery. Nankodo, 2019.
- Goldberg DJ, Whitworth J. Laser and light therapy of benign pigmented epidermal lesions. Dermatol Ther. 2000;13(2):169-175.
- Hantash BM, Stewart DB, Cooper ZA, et al. Selective photothermolysis of seborrheic keratoses using a novel 755-nm long-pulse alexandrite laser. Dermatol Surg. 2007;33(4):525-534.
