What is Seborrheic Keratosis?
Seborrheic keratosis (pronounced seb-o-REE-ik ker-uh-TOE-sis) is one of adults' most common benign skin growths. These harmless growths appear as brown, black, or tan lesions with a characteristic waxy, wart-like, or scaly surface.
Many people become concerned when they first notice these growths because they can resemble melanoma or other skin cancers. However, seborrheic keratoses (the plural form) are completely non-cancerous and pose no health risk beyond occasional irritation.
How Common is Seborrheic Keratosis?
Seborrheic keratosis affects nearly 83 million Americans, making it one of the most frequent reasons for dermatology visits. Most people will develop at least one seborrheic keratosis in their lifetime, with the prevalence increasing significantly after age 50.
What Causes Seborrheic Keratosis?
Medical researchers haven't pinpointed the exact cause of seborrheic keratosis, but several factors contribute to its development:
Age-Related Changes
The primary risk factor for developing seborrheic keratosis is age. These growths rarely appear before age 30 and become increasingly common in middle-aged and older adults. By age 60, more than 90% of people have at least one seborrheic keratosis.
Genetic Factors
If your parents or grandparents had numerous seborrheic keratoses, you're more likely to develop them as well. This strong genetic component suggests inherited factors play a significant role in their formation.
Sun Exposure
While not directly caused by sun damage (unlike actinic keratosis), evidence suggests that ultraviolet (UV) exposure may contribute to developing seborrheic keratosis. However, these growths also commonly appear in areas with little sun exposure, indicating that UV radiation is not the primary cause.
Hormonal Influences
Some studies suggest that hormonal changes, particularly during pregnancy or menopause, may trigger the development or rapid growth of seborrheic keratoses.
Unknown Triggers
Despite decades of research, dermatologists still don't fully understand all the mechanisms that lead to seborrheic keratosis formation. This knowledge gap continues to drive ongoing research into these common skin growths.
Recognizing Seborrheic Keratosis: Signs and Symptoms
Seborrheic keratoses have several distinctive characteristics that help differentiate them from other skin conditions:
Physical Appearance
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Shape and Size: Round or oval-shaped lesions that typically range from tiny spots to several centimeters in diameter
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Texture: Raised growths with a rough, waxy, or velvety surface that often looks "stuck on" to the skin
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Color Variation: Can appear in various shades from light tan to dark brown or black
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Borders: Usually have well-defined borders that don't fade into surrounding skin
Common Locations
These growths most frequently appear on:
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Face (particularly around the temples and cheeks)
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Chest
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Upper back
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Shoulders
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Abdominal area
However, they can develop anywhere on the body except the palms, soles, and mucous membranes.
Sensations and Symptoms
Most seborrheic keratoses are asymptomatic, meaning they cause no physical discomfort. However, some people experience:
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Mild itching, especially when the growth is new
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Irritation if the lesion is located where clothing rubs against it
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Cosmetic concerns, particularly when growths appear on visible areas like the face
It's important to note that pain, bleeding, or rapid changes in a seborrheic keratosis are unusual and warrant immediate medical attention.
When to See a Doctor About Seborrheic Keratosis
While seborrheic keratoses are benign, certain circumstances should prompt a visit to your dermatologist:
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New growths that appear suddenly or grow rapidly
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Changes in existing lesions, including size, shape, color, or texture
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Bleeding, pain, or intense itching from a seborrheic keratosis
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Multiple new growths appearing over a short period
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Uncertainty about diagnosis, especially if you have risk factors for skin cancer
Remember that only a qualified healthcare provider can definitively diagnose seborrheic keratosis and rule out more serious conditions.
Diagnosing Seborrheic Keratosis
Dermatologists typically diagnose seborrheic keratosis through:
Visual Examination
Experienced dermatologists can often identify seborrheic keratosis through visual inspection alone. They may use a dermatoscope (a special magnifying tool) to examine the growth's surface patterns and blood vessel structures.
Dermoscopy
This enhanced examination technique uses polarized light and magnification to reveal characteristic features of seborrheic keratosis not visible to the naked eye, such as milia-like cysts and comedo-like openings.
Biopsy
If the diagnosis is uncertain, your doctor may recommend a skin biopsy. This involves removing a small sample of the growth and examining it under a microscope to confirm that it's seborrheic keratosis and not a more concerning condition.
Treatment Options for Seborrheic Keratosis
Since seborrheic keratoses are benign, treatment is not medically necessary unless the growths become irritated or cause cosmetic concerns. However, many people choose to have them removed for comfort or aesthetic reasons.
Cryotherapy (Freezing)
How it works: The dermatologist applies liquid nitrogen to freeze the growth, causing it to blister and eventually fall off.
Best for: Small to medium-sized lesions, particularly on the trunk or extremities.
Recovery time: The treated area may blister and scab for 1-2 weeks before healing.
Pros: Quick, in-office procedure with minimal discomfort.
Cons: May cause temporary hypopigmentation (lightening of the skin) or hyperpigmentation (darkening of the skin), particularly in people with darker skin tones.
Curettage and Electrodesiccation
How it works: After numbing the area with local anesthesia, the doctor scrapes off the growth with a curette (a spoon-shaped surgical tool) and may use an electric current to control bleeding.
Best for: Larger or thicker seborrheic keratoses that might not respond well to freezing.
Recovery time: The wound typically heals within 2-3 weeks.
Pros: More thorough removal with less chance of recurrence.
Cons: Higher risk of scarring compared to other methods.
Laser Therapy
How it works: Targeted laser energy destroys the abnormal cells while minimizing damage to surrounding tissue.
Best for: Multiple seborrheic keratoses, especially in sensitive areas or cosmetically essential sites like the face.
Recovery time: Healing usually occurs within 1-2 weeks.
Pros: Precise treatment with minimal risk of scarring.
Cons: May require multiple sessions and is more expensive than other options.
Shave Excision
How it works: After applying local anesthesia, the dermatologist uses a surgical blade to shave the growth flush with the surrounding skin.
Best for: Raised lesions with distinct borders.
Recovery time: The area typically heals within 1-2 weeks.
Pros: Provides a tissue sample for pathological examination if needed.
Cons: Can occasionally leave a small scar.
Topical Treatments
While less commonly used than procedural approaches, certain medications may help reduce the appearance of seborrheic keratoses:
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Hydrogen peroxide solutions: Formulations like 40% hydrogen peroxide (ESKATA®) are FDA-approved for treating seborrheic keratosis.
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Trichloroacetic acid: Chemical peels containing this acid may help reduce the thickness and visibility of some growths.
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Retinoids: These vitamin A derivatives help reduce the appearance of small, early seborrheic keratoses.
Living with Seborrheic Keratosis: Prevention and Management
While you cannot prevent seborrheic keratoses entirely, you can manage them effectively:
Regular Skin Examinations
Perform monthly self-examinations to monitor existing growths and identify new ones. Use the "ABCDE" rule, typically applied to melanom,a as a general guide for concerning changes:
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Asymmetry: One half looks different from the other
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Border: Irregular, ragged, or poorly defined edges
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Color: Variation in color within the growth
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Diameter: Larger than 6mm (about the size of a pencil eraser)
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Evolving: Changing in size, shape, color, or symptoms
Sun Protection
While sun exposure isn't the primary cause of seborrheic keratosis, it can worsen overall skin health and potentially contribute to new growths. Protect your skin by:
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Applying broad-spectrum sunscreen with SPF 30+ daily
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Wearing protective clothing, hats, and sunglasses
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Seeking shade during peak sun hours (10 a.m. to 4 p.m)
Gentle Skincare
To prevent irritation of existing seborrheic keratoses:
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Avoid harsh scrubs or exfoliants on areas with growths
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Use gentle cleansers that won't irritate the skin
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Apply moisturizers to keep the skin hydrated
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Avoid picking or scratching at the growths
Regular Dermatology Visits
Schedule annual skin checks with a dermatologist, especially if you:
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Have a family history of skin cancer
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Have numerous seborrheic keratoses
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Notice changes in your existing growths
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Have a history of significant sun exposure
Conditions That May Resemble Seborrheic Keratosis
Several skin conditions can look similar to seborrheic keratosis, which is why professional evaluation is critical:
Actinic Keratosis
Unlike benign seborrheic keratoses, actinic keratoses are precancerous lesions caused by sun damage. They typically appear rough, scaly patches on sun-exposed areas and may progress to squamous cell carcinoma if left untreated.
Melanoma
This dangerous form of skin cancer can sometimes resemble seborrheic keratosis. Warning signs include asymmetry, irregular borders, multiple colors, increasing size, and evolving appearance.
Solar Lentigo (Age Spots)
These flat, pigmented spots are caused by sun exposure and are entirely benign. Unlike seborrheic keratoses, they are not raised and have a smooth surface.
Dermatosis Papulosa Nigra
This condition, more common in people with darker skin tones, primarily causes small, benign papules on the face. These are a variant of seborrheic keratosis.
Frequently Asked Questions About Seborrheic Keratosis
Q: Can seborrheic keratosis turn into cancer? A: No, seborrheic keratoses are benign and do not become skin cancer. However, it's essential to have any changes in skin growth evaluated by a dermatologist to confirm the diagnosis.
Q: Why do I suddenly have multiple seborrheic keratoses? A: The sudden appearance of numerous seborrheic keratoses (sometimes called the "sign of Leser-Trélat") is rare but can occasionally be associated with internal malignancies. If you experience this, consult your doctor promptly.
Q: Will removing a seborrheic keratosis leave a scar? A: Most removal methods aim to minimize scarring, but some risk always exists. The likelihood of noticeable scarring depends on the size and location of the growth, the removal method used, and your skin's healing characteristics.
Q: Do seborrheic keratoses grow back after removal? A: When completely removed, individual seborrheic keratoses typically don't grow back in the same spot. However, new growths may develop in nearby areas over time.
Q: Are seborrheic keratoses contagious? A: No, seborrheic keratoses are not contagious and cannot be spread from person to person or from one part of the body to another through contact.
Conclusion
Seborrheic keratosis represents one of the most common benign skin conditions people encounter as they age. While these growths may cause cosmetic concerns, they pose no health risk and don't require treatment unless they become irritated or bothersome.
Understanding the characteristics of seborrheic keratosis can help you distinguish these harmless growths from more concerning skin conditions. However, always consult a dermatologist for proper evaluation and diagnosis when in doubt.
If you choose to have seborrheic keratoses removed, multiple effective treatment options are available. Discuss with your healthcare provider which approach might work best for your situation.
Disclaimer: This information is provided for educational purposes only and is not intended to replace professional medical advice. Always consult with a qualified healthcare provider regarding any skin concerns or conditions.
