Definition

Seborrheic keratosis, also known as senile keratosis, is a common skin growth that manifests as a protrusion. These growths are benign and non-cancerous, though their number tends to increase with age. Despite their appearance, keratosis is often misinterpreted as skin cancer. Seborrheic keratosis is neither dangerous nor contagious. Most people will experience at least one seborrheic keratosis in their lifetime. However, a doctor can assist in removing them if they become bothersome, either due to appearance or because they are easily irritated by clothing.

Seborrheic keratosis typically appears in shades of brown, black, or light brown. The growth may have a waxy or scaly appearance and is slightly raised. These lumps develop gradually and can appear anywhere on the body except the palms, soles, or mucous membranes of the mouth and nose. Common sites for seborrheic keratosis include the face, neck, chest, shoulders, back, and skin folds.

A 2015 study found that seborrheic keratosis affected approximately 83 million people in the United States. In the United Kingdom, 30% of individuals have seborrheic keratosis by age 40, and by age 70, 75% will have experienced it.

Causes

Seborrheic keratosis occurs when skin cells grow abnormally, but the exact cause remains unknown. This condition often runs in families, suggesting a possible hereditary factor. Having one seborrheic keratosis increases the likelihood of developing more. It is neither harmful nor contagious.

Risk factor

The risk factors for seborrheic keratosis or senile keratosis include:

1. Advanced Age

This condition typically first appears in one's 30s or 40s and becomes more common with age. It is rare in individuals under 20 years old.

2. Family History of Keratosis

This skin condition frequently occurs within families and is often inherited. The risk increases with the number of family members affected.

3. Pregnancy and Hormone Therapy

Seborrheic keratosis may emerge during pregnancy. It can also develop in individuals undergoing estrogen replacement therapy, such as menopausal women.

4. Frequent Sun Exposure

Research indicates that one type of seborrheic keratosis, the adenoid type, is more prevalent on sun-exposed skin than on protected skin. However, senile keratosis can also occur on covered skin during outdoor activities.

5. Lighter Skin Tone

Seborrheic keratosis is more common in individuals with fair skin, though it can also affect those with darker skin.

Symptoms

Seborrheic keratosis typically develops gradually. Signs and symptoms may include:

• Round or oval bumps with a waxy or slightly rough texture, usually on the face, chest, shoulders, or back.
• Slightly elevated or flat growths with a scaly surface that appear "stuck on."
• Sizes range from very small to over an inch (2.5 centimeters) in diameter.
• They can occur singly or in clusters.
• Small growths may appear near the eyes or other facial areas, sometimes referred to as moles or dermatosis papulosa nigra, commonly affecting brown or black skin.
• Colors range from light brown to black.
• Itching or irritation.
• Bumps may catch on clothing or jewelry.

Typically, these lumps start small and rough, growing larger and thicker over time, with a wart-like surface. They appear "stuck on" the skin or waxy and slightly raised. They can develop on the scalp, face, chest, shoulders, abdomen, and back.

Diagnosis

Diagnosing seborrheic keratosis, or senile keratosis, is typically straightforward through skin observation. The doctor will inquire about the patient’s symptoms and their medical and family history. If uncertainty exists or further examination is needed, the doctor may perform a skin biopsy. This involves taking a sample of the lump for laboratory analysis. A pathologist examines the biopsy under a microscope to confirm whether the lump is seborrheic keratosis or another condition.

Management

Seborrheic keratosis is generally harmless and doesn't require treatment. However, a doctor may remove the lump if it resembles skin cancer, catches on clothing or jewellery, becomes easily irritated, or is cosmetically bothersome.

Possible treatments for seborrheic keratosis include:

1. Cryotherapy

The doctor applies or sprays very cold liquid nitrogen onto the lump. This freezes and destroys the lump, which then falls off after a few days. Occasionally, the treated area may form a scab before healing completely.

2. Electrosurgery and Curettage

In electrosurgery, the lump is numbed with a local anesthetic, and then destroyed with an electric current. The destroyed lump is then scraped away using a curette, a scoop-like instrument. This procedure, known as curettage, may cause minor bleeding but typically doesn't require stitches. Sometimes, only electrosurgery or curettage is needed.

3. Excision

Similar to curettage, excision involves cutting out the keratosis. This method may also be used to obtain a tissue sample for laboratory analysis.

4. Ablation

This procedure uses a special laser to vaporize the lump.

5. Hydrogen Peroxide Solution

A 40% hydrogen peroxide solution can damage the cells of seborrheic keratosis, but it is only available by prescription.

6. Zinc Nitrate Solution

This solution can shrink or completely remove seborrheic keratosis within six months.

To avoid complications such as bleeding, inflammation, or infection, it is advisable not to remove keratosis by plucking or scratching it yourself. After removal, the skin in the affected area may be slightly lighter in color, but this difference typically fades over time. Seborrheic keratosis usually does not recur in the same spot, though it may appear elsewhere on the body.

Complications

Seborrheic or senile keratosis is benign and non-contagious, thus not associated with serious complications. Potential issues include keratosis catching on clothing or jewelry, skin irritation, and cosmetic concerns. Attempting self-removal may lead to complications such as bleeding, skin inflammation, and infection. Medical removal procedures may cause minor bleeding and lighter skin coloration at the treated site.

Prevention

Preventing seborrheic keratosis is challenging, as it can be hereditary and does not always develop in sun-exposed areas. However, to prevent complications, avoid self-treatment and seek medical assistance if the condition becomes bothersome, easily irritated, or cosmetically unappealing.

When to see a doctor?

While seborrheic keratosis is generally not severe, it’s important not to ignore skin lumps. Differentiating between seborrheic keratosis and skin cancer, particularly melanoma, can be difficult. Consult a doctor if:

• A new lump appears.
• An existing lump changes.
• There is only one lump (keratosis usually appears in multiples).
• The lump has an unusual color, such as purple, blue, or reddish-black.
• The lump has irregular, unclear, or uneven borders.
• The lump is painful or easily irritated.

If you are concerned about a lump, consult a general practitioner or dermatologist. Do not underestimate the condition, as it could potentially be serious and life-threatening.

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