Keratoacanthoma: Symptoms, Diagnosis, and Treatment Explained

Introduction

Keratoacanthoma is a skin condition that often causes concern due to its rapid growth and resemblance to skin cancer. First identified in the early 20th century, it is classified as a low-grade skin tumor that typically appears on sun-exposed areas such as the face, neck, and hands. While generally benign, meaning it is not cancerous, Keratoacanthoma can be challenging to differentiate from squamous cell carcinoma, a type of skin cancer. This article provides a thorough overview of Keratoacanthoma, including its risk factors, symptoms, diagnostic tests, treatment options, and self-care tips for managing symptoms at home. By understanding this condition, patients can take proactive steps to seek appropriate medical care and maintain their skin health.

What is Keratoacanthoma?

Keratoacanthoma is a skin condition characterized by a rapidly growing lesion. This article will explore its risk factors, symptoms, diagnostic tests, medications, procedures, and home care strategies to help patients manage their symptoms effectively.

Description of Keratoacanthoma

Keratoacanthoma (KA) is a type of skin tumor that originates in the hair follicles, typically presenting as a dome-shaped nodule with a central keratin-filled crater. The lesion usually grows quickly over a few weeks to months, reaching a size of 1 to 2 centimeters. Although it often resembles squamous cell carcinoma, a common form of skin cancer, Keratoacanthoma is generally considered benign. However, due to its appearance and aggressive growth, healthcare providers often recommend removing the lesion to rule out malignancy.

Keratoacanthoma progresses through three distinct phases: the growth phase, the stationary phase, and the regression phase. During the growth phase, the lesion enlarges rapidly. In the stationary phase, it stops growing and remains stable for a period. Finally, in the regression phase, the lesion may shrink and resolve on its own, although this process can take several months.

While not extremely common, Keratoacanthoma primarily affects older adults, particularly those with fair skin and significant sun exposure. It is estimated that about 1 in 1,000 people will develop this condition in their lifetime. Although the lesion can resolve on its own, medical evaluation and treatment are often recommended to prevent complications and ensure an accurate diagnosis.

Risk Factors for Developing Keratoacanthoma

Lifestyle Risk Factors

Several lifestyle factors can increase the risk of developing Keratoacanthoma. One of the most significant is prolonged exposure to ultraviolet (UV) radiation from the sun. Individuals who spend a lot of time outdoors without adequate sun protection, such as sunscreen or protective clothing, are at higher risk. Additionally, frequent use of tanning beds increases the risk due to the concentrated UV radiation emitted by these devices.

Smoking is another lifestyle factor that may contribute to the development of Keratoacanthoma. Tobacco smoke contains harmful chemicals that can damage skin cells, potentially leading to abnormal growths like Keratoacanthoma. Exposure to certain chemicals, such as tar or industrial pollutants, may also increase the risk of this skin condition.

Medical Risk Factors

Individuals with a history of skin conditions, particularly those who have had squamous cell carcinoma or other forms of skin cancer, are at an elevated risk of developing Keratoacanthoma. Additionally, people with weakened immune systems, such as those undergoing immunosuppressive therapy or living with conditions like HIV/AIDS, may be more susceptible to this condition.

Chronic skin inflammation or injury, such as burns or scars, may also increase the likelihood of developing Keratoacanthoma, as damaged skin is more prone to abnormal cell growth. Patients who have undergone organ transplants and are taking immunosuppressive medications are at a significantly higher risk of developing skin lesions, including Keratoacanthoma.

Genetic and Age-Related Risk Factors

Age is a major risk factor for Keratoacanthoma, with most cases occurring in individuals over 60. As we age, our skin becomes more vulnerable to damage from UV radiation and other environmental factors, leading to the development of abnormal growths like Keratoacanthoma.

There may also be a genetic component to Keratoacanthoma development. Some studies suggest that individuals with a family history of skin cancer or other skin conditions may be more likely to develop Keratoacanthoma. Additionally, people with fair skin, light-colored eyes, and a tendency to burn rather than tan are at higher risk due to their skin’s reduced ability to protect against UV damage.

Clinical Manifestations of Keratoacanthoma

Painless Nodule

Approximately 90% of patients with Keratoacanthoma present with a painless nodule, typically a firm, dome-shaped growth on the skin. The absence of pain distinguishes Keratoacanthoma from other skin conditions, such as infections or inflammatory lesions, which often cause discomfort. The nodule forms due to rapid cell proliferation in the outer skin layer, specifically the keratinocytes. While the nodule itself is painless, it is important to monitor its growth, as it can cause discomfort in later stages if it becomes large enough to press on surrounding tissues.

Rapid Growth

Rapid growth is observed in 70-80% of Keratoacanthoma cases. This characteristic growth pattern is a hallmark of the condition, with the nodule often doubling in size within a few weeks. The rapid proliferation of keratinocytes leads to the sudden appearance of a large lesion, which can be alarming for patients. This growth typically occurs during the early stages, and the lesion may reach 1-2 cm in diameter within 4-6 weeks. Despite the fast growth, Keratoacanthoma is generally considered a low-grade skin tumor, and the lesion may eventually stabilize or even regress without treatment in some cases.

Central Keratin Plug

A central keratin plug is present in about 80% of Keratoacanthoma cases. This plug is composed of keratin, a protein that is a key component of the skin, hair, and nails. The plug forms in the center of the nodule and gives Keratoacanthoma its characteristic appearance. As keratinocytes multiply, they produce excess keratin, which accumulates in the center of the lesion. This plug can sometimes be mistaken for a scab or crust, but it is a defining feature of Keratoacanthoma. The presence of the keratin plug is often used by healthcare providers to differentiate Keratoacanthoma from other skin conditions, such as squamous cell carcinoma.

Crusting

Crusting occurs in approximately 60% of Keratoacanthoma cases. This symptom is closely related to the formation of the central keratin plug. As the keratin accumulates, it can harden and form a crust on the surface of the lesion. Crusting may also occur if the lesion becomes irritated or damaged, leading to the formation of a protective layer over the nodule. While crusting is not typically painful, it can be unsightly and may cause concern for patients. It is important to avoid picking at the crust, as this can lead to infection or further irritation.

Ulceration

Ulceration is seen in about 30-40% of Keratoacanthoma cases, particularly in more advanced stages. As the lesion grows, the skin over the nodule may break down, leading to the formation of an open sore or ulcer. Ulceration occurs when the rapid proliferation of keratinocytes outpaces the skin’s ability to maintain an intact surface. This breakdown of the skin barrier can increase the risk of infection and may cause discomfort or tenderness. Patients who notice ulceration should seek medical attention, as this may indicate a more aggressive form of the disease.

Erythema

Erythema, or redness of the skin, is present in approximately 40% of Keratoacanthoma cases. This redness occurs as a result of increased blood flow to the area surrounding the nodule. The body’s immune response to the abnormal growth of keratinocytes can cause inflammation, leading to erythema. While erythema is not typically associated with pain, it can be a sign of irritation or inflammation, particularly if the lesion is growing rapidly or has become ulcerated. In some cases, erythema may be more pronounced in patients with lighter skin tones.

Induration

Induration, or hardening of the skin, is observed in about 50% of Keratoacanthoma cases. This hardening occurs as the lesion grows and the keratinocytes produce excess keratin. The nodule becomes firm to the touch, and the surrounding skin may also feel thickened. Induration can make the lesion more noticeable and may cause concern for patients, particularly if it occurs rapidly. While induration is not typically painful, it is a sign that the lesion is progressing, and patients should seek medical evaluation if they notice this symptom.

Scaling

Scaling is seen in approximately 30% of Keratoacanthoma cases. This symptom occurs as the outer layer of the skin becomes dry and begins to flake off. Scaling is often associated with the formation of the central keratin plug and crusting. The rapid turnover of keratinocytes can lead to an accumulation of dead skin cells on the surface of the lesion, which then shed in the form of scales. While scaling is not typically harmful, it can be unsightly and may cause concern for patients. Moisturizing the area may help alleviate some of the dryness and scaling.

Itching

Itching is reported in about 20% of Keratoacanthoma cases. This symptom is usually mild but can be bothersome for some patients. Itching occurs as a result of the body’s immune response to the abnormal growth of keratinocytes. The release of inflammatory chemicals, such as histamines, can stimulate nerve endings in the skin, leading to the sensation of itching. Patients should avoid scratching the lesion, as this can lead to further irritation or infection. If itching is severe, over-the-counter antihistamines or topical treatments may provide relief.

Tenderness

Tenderness is present in approximately 25% of Keratoacanthoma cases, particularly in more advanced stages of the disease. As the lesion grows, it may press on surrounding tissues, causing discomfort or tenderness. Ulceration or infection of the lesion can also contribute to tenderness. While Keratoacanthoma is typically painless in its early stages, patients who experience tenderness should seek medical evaluation, as this may be a sign that the lesion is becoming more aggressive or complicated by secondary infection.

Treatment Options for Keratoacanthoma

Medications for Keratoacanthoma

5-Fluorouracil (5-FU)

5-Fluorouracil (5-FU) is a topical chemotherapy commonly used to treat skin cancers, including keratoacanthoma. It works by inhibiting the growth of abnormal cells.

Applied directly to the lesion, it is often recommended when surgery is not feasible or for smaller lesions. It may also be a first-line treatment for early-stage keratoacanthoma.

Patients can expect the lesion to shrink gradually over several weeks. Common side effects include redness and irritation at the application site.

Imiquimod

Imiquimod is a topical immune response modifier that stimulates the body’s immune system to target and destroy abnormal skin cells.

Applied directly to the lesion several times a week, it is often used for small or superficial lesions, particularly when surgery is not an option.

Improvement typically occurs over several weeks to months. Redness, swelling, and irritation are common side effects.

Methotrexate

Methotrexate is an immunosuppressive drug used for rapidly growing keratoacanthoma or when surgery is not possible.

Administered either orally or by injection, it is reserved for aggressive or advanced cases and may also be used for multiple lesions.

Methotrexate can slow lesion growth, but improvement may take several weeks. Regular monitoring is required due to potential side effects, such as liver toxicity and bone marrow suppression.

Dexamethasone

Dexamethasone is a corticosteroid that reduces inflammation and can help shrink keratoacanthoma lesions.

It is used when the lesion causes significant inflammation or swelling and may be administered as an injection or taken orally.

Dexamethasone provides rapid relief from inflammation but is usually combined with other treatments, as it does not directly target abnormal cells.

Topical Retinoids

Topical retinoids, derivatives of vitamin A, help regulate cell growth and differentiation. They can be used to treat keratoacanthoma.

Applied directly to the skin, they are often combined with other topical treatments like 5-Fluorouracil or Imiquimod, typically for smaller or early-stage lesions.

Patients may see a reduction in lesion size over several weeks, though skin irritation is a common side effect.

Procedures for Keratoacanthoma Removal

Cryotherapy

Cryotherapy involves freezing the keratoacanthoma lesion with liquid nitrogen to destroy abnormal cells.

This quick, in-office procedure is often used for small or superficial lesions and does not require anesthesia.

The lesion typically blisters and falls off within a few weeks. Some scarring may occur, but the risk of recurrence is low.

Surgical Excision

Surgical excision involves removing the keratoacanthoma lesion with a scalpel.

This is the preferred treatment for larger or more advanced lesions, ensuring complete removal of abnormal tissue. It is usually performed under local anesthesia.

Surgical excision has a high success rate, with a low likelihood of recurrence. However, scarring is a potential outcome.

Mohs Micrographic Surgery

Mohs micrographic surgery removes the keratoacanthoma lesion layer by layer, examining each under a microscope to ensure complete removal of cancerous cells.

This precise procedure is often used for larger lesions or those in cosmetically sensitive areas, such as the face, and minimizes the removal of healthy tissue.

Mohs surgery has an extremely high cure rate, with minimal scarring compared to traditional excision methods.

Radiation Therapy

Radiation therapy uses targeted radiation to destroy abnormal cells in the keratoacanthoma lesion.

This treatment is typically reserved for cases where surgery is not an option, such as for elderly patients or those with lesions in difficult-to-treat areas. It may also be used for recurrent lesions.

Patients can expect gradual improvement over several weeks, though side effects like skin irritation and fatigue are possible.

Photodynamic Therapy (PDT)

Photodynamic therapy (PDT) involves applying a photosensitizing agent to the lesion and exposing it to a specific wavelength of light to destroy abnormal cells.

This non-invasive treatment is used for superficial keratoacanthoma lesions or for patients unable to undergo surgery. It is typically done in an outpatient setting.

The lesion usually shrinks over a few weeks, though multiple sessions may be required. Redness and swelling are common side effects.

Cimetidine

Cimetidine, an oral medication typically used to treat stomach ulcers, has shown some effectiveness in treating keratoacanthoma by modulating the immune system.

This experimental treatment is usually reserved for patients with multiple lesions or those who cannot tolerate other treatments.

While outcomes vary, some patients may experience a reduction in lesion size over time. However, more research is needed to fully understand its effectiveness.

Improving Keratoacanthoma and Seeking Medical Help

In addition to medical treatments, several home remedies and lifestyle changes can help manage keratoacanthoma and improve overall skin health:

1. Avoiding sun exposure: Limiting sun exposure can prevent further skin damage and reduce the risk of developing additional keratoacanthoma lesions.
2. Using sunscreen: Applying broad-spectrum sunscreen with an SPF of 30 or higher protects the skin from harmful UV rays.
3. Maintaining a healthy diet: A balanced diet rich in antioxidants supports skin health and immune function.
4. Staying hydrated: Drinking plenty of water keeps the skin hydrated and may improve its ability to heal.
5. Regular skin checks: Performing self-examinations and scheduling regular check-ups with a healthcare provider can help detect new lesions early.

Telemedicine offers a convenient way to consult with a healthcare provider about keratoacanthoma. Through virtual visits, patients can discuss symptoms, receive a diagnosis, and explore treatment options without leaving home. This is especially beneficial for those with limited mobility or living in remote areas.

Living with Keratoacanthoma: Tips for Better Quality of Life

Living with keratoacanthoma can be challenging, but there are steps you can take to improve your quality of life:

1. Follow your treatment plan closely and attend all follow-up appointments to monitor your condition.
2. Protect your skin from the sun by wearing protective clothing and using sunscreen daily.
3. Stay informed about your condition and ask your healthcare provider any questions you may have.
4. Consider joining a support group for individuals with skin conditions to share experiences and coping strategies.

Conclusion

Keratoacanthoma is a skin condition that can resemble skin cancer but is generally less aggressive. Early diagnosis and treatment are crucial to prevent complications and ensure the best outcomes. With a range of treatment options, including medications, procedures, and lifestyle changes, keratoacanthoma can be effectively managed.

If you are concerned about a skin lesion or need guidance on managing keratoacanthoma, our telemedicine practice is here to help. Schedule a virtual consultation with one of our healthcare providers today to discuss your symptoms and explore the best treatment options for you.

James Kingsley

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