Flat Warts: Causes, Symptoms, and Effective Treatment Options

Introduction

Flat warts, also known as verruca plana, are a common skin condition caused by the human papillomavirus (HPV). These warts are typically small, smooth, and slightly raised, often appearing in clusters on the face, hands, or legs. While flat warts are generally harmless, they can cause discomfort or embarrassment. Historically, warts have been recognized for centuries, with their viral association confirmed in the 20th century. This article provides a comprehensive overview of flat warts, covering risk factors, symptoms, diagnostic methods, treatments, and self-care strategies. Understanding the condition helps patients make informed decisions about managing and treating flat warts effectively.

What Are Flat Warts?

Flat warts are small, smooth, and slightly raised skin growths caused by HPV. This article will discuss their risk factors, symptoms, diagnostic tests, medications, procedures, and home remedies for managing the condition.

Description of Flat Warts

Flat warts are skin lesions caused by specific HPV strains, particularly types 3, 10, 28, and 49. These warts are smaller and smoother than other types, with a flat or slightly raised surface. They often appear in clusters on the face, neck, hands, wrists, and knees. Flat warts are more common in children and young adults but can affect people of any age.

The progression of flat warts varies. Some may resolve without treatment, while others persist for months or years. The virus is contagious, spreading through direct contact with an infected person or contaminated surfaces like towels or razors.

Flat warts affect an estimated 7-10% of the population at some point. They are more common in individuals with weakened immune systems, such as those with HIV or undergoing chemotherapy. While generally benign, flat warts can cause cosmetic concerns and, in rare cases, become painful if irritated.

Risk Factors for Developing Flat Warts

Lifestyle Risk Factors

Certain lifestyle factors increase the likelihood of developing flat warts. The most significant risk is direct skin-to-skin contact with someone who has warts, either through casual contact or sharing personal items like towels, razors, or clothing. Warm, moist environments, such as public swimming pools or locker rooms, also facilitate the spread of the virus.

Frequent shaving, especially on the face or legs, can increase the risk by creating tiny cuts in the skin, allowing the virus to enter. Poor hygiene, such as not washing hands regularly or failing to clean shared surfaces, can also contribute to the virus’s spread.

Medical Risk Factors

Individuals with weakened immune systems are at higher risk of developing flat warts. This includes people with conditions like HIV/AIDS or those undergoing treatments that suppress the immune system, such as chemotherapy or long-term corticosteroid use. A weakened immune system makes it harder for the body to fight off viral infections, including HPV.

People with eczema or other skin conditions that cause breaks in the skin barrier may also be more susceptible to contracting the virus. Damaged skin provides an entry point for infection. Chronic stress, which weakens the immune response, may further increase the risk of developing warts.

Genetic and Age-Related Risk Factors

Genetics may play a role in susceptibility to flat warts. Some individuals may have a genetic predisposition that makes them more vulnerable to HPV infections, including the strains that cause flat warts. However, more research is needed to fully understand the genetic factors involved.

Age is another important factor. Flat warts are more common in children and young adults, likely due to their developing immune systems and increased exposure to the virus in school or social settings. As people age, their immune systems may become more adept at fighting off the virus, which could explain why flat warts are less common in older adults.

Clinical Manifestations of Flat Warts

Flat, Smooth Surface

Flat warts, or verruca plana, are characterized by their flat, smooth surface, present in about 90% of cases. Unlike other warts with a rough or raised texture, flat warts blend into the skin. The virus affects the uppermost skin layer, causing a subtle thickening without the pronounced elevation seen in other warts. This manifestation is more common in children and adolescents due to their developing immune systems.

Skin-Colored or Slightly Brown

Flat warts are typically skin-colored or slightly brown in about 80% of cases. Their color often blends with the surrounding skin, making them less noticeable than other warts. In fair-skinned individuals, they may appear pink or light brown, while in darker-skinned individuals, they can take on a deeper brown hue. This subtle color variation makes flat warts difficult to detect early, especially in areas where skin tone naturally varies.

Small Size

Flat warts are generally small, measuring between 1 to 5 millimeters in diameter, typical in over 85% of cases. Their small size is due to the limited extent of viral infection in the skin. The virus primarily affects the top skin layer, causing minimal thickening and growth. Despite their size, flat warts can multiply and spread, especially if scratched or irritated. In some cases, they may cluster together, forming larger patches.

Grouped Appearance

Flat warts often appear in groups or clusters, a feature seen in about 70% of cases. This occurs because the virus can spread from one wart to nearby skin, leading to new lesions. The grouped nature is common in frequently touched or exposed areas, such as the face and hands. In some patients, the warts may form a linear pattern, known as the “Koebner phenomenon,” where the virus spreads along areas of skin trauma, like scratches or cuts.

No Pain

Flat warts are typically painless in 95% of cases. Unlike plantar warts, which can cause discomfort due to pressure on the feet, flat warts do not penetrate deeply into the skin, so they do not cause pain. The lack of pain often delays treatment, as the warts do not interfere with daily activities. However, they can still cause cosmetic concerns, especially when they appear on visible areas like the face or hands.

No Itching

In about 90% of cases, flat warts do not cause itching. The virus affects the outer skin layer without triggering an inflammatory response, which is typically associated with itching. However, in rare cases, patients may experience mild irritation or itching, particularly if the warts are scratched or rubbed frequently. If itching occurs, it may indicate secondary irritation or infection and should be evaluated by a healthcare provider.

May Be Slightly Raised

While flat warts are generally smooth and flat, they may be slightly raised in about 60% of cases. This slight elevation is due to skin thickening caused by the viral infection. The raised appearance is usually subtle, making the warts appear as small, smooth bumps. This feature is more common in areas with thicker skin, such as the hands or legs. The raised nature can make them more noticeable, especially when they occur in clusters.

Common in Children and Adolescents

Flat warts are most commonly seen in children and adolescents, with up to 75% of cases occurring in this age group. This is likely due to younger individuals having less developed immune systems, making them more susceptible to HPV infections. Additionally, children and adolescents are more likely to engage in activities that expose them to the virus, such as playing in communal areas or sharing personal items like towels. The warts often appear on the face, hands, and legs, areas frequently exposed to the environment.

Often Found on Face and Hands

Flat warts are most commonly found on the face and hands, with about 80% of cases involving these areas. The face and hands are more exposed to the environment, increasing the likelihood of contact with the virus. Additionally, these areas are frequently touched, which can lead to the spread of the virus from one part of the body to another. In some cases, flat warts may also appear on the legs, particularly in individuals who shave, as the virus can spread through small cuts or abrasions in the skin.

Diagnostic Evaluation of Flat Warts

The diagnosis of flat warts is primarily made through a clinical examination by a healthcare provider. During the examination, the provider will visually inspect the warts and assess their appearance, size, and location. In most cases, the diagnosis can be made based on the characteristic features of flat warts, such as their flat, smooth surface and skin-colored or slightly brown appearance. However, in some cases, additional diagnostic tests may be needed to confirm the diagnosis, especially if the warts are atypical in appearance or if other skin conditions are suspected. Below are some of the diagnostic tests that may be used to evaluate flat warts.

Dermatoscopy

Dermatoscopy is a non-invasive diagnostic tool that allows healthcare providers to examine the skin in detail using a handheld device called a dermatoscope. This tool magnifies the skin and provides enhanced lighting, allowing the provider to see structures beneath the surface of the skin that are not visible to the naked eye. Dermatoscopy is commonly used to evaluate skin lesions, including flat warts, and can help differentiate them from other types of skin growths, such as moles or skin cancer. The procedure is painless and does not require any preparation or recovery time.

Results that Indicate Flat Warts

When examining flat warts under a dermatoscope, healthcare providers typically look for specific features, such as a smooth surface, the absence of blood vessels, and the presence of small, pinpoint dots, which are clotted capillaries. These findings are characteristic of flat warts and can help confirm the diagnosis. If the dermatoscopy findings are inconclusive or if the provider suspects another skin condition, additional diagnostic tests, such as a biopsy, may be recommended. If the results do not indicate flat warts, the provider may explore other possible diagnoses, such as seborrheic keratosis or actinic keratosis.

Biopsy

A biopsy involves removing a small sample of skin tissue for further examination under a microscope. This test is typically performed if the diagnosis of flat warts is uncertain or if the warts do not respond to standard treatments. During the procedure, the healthcare provider will numb the area with a local anesthetic and then use a small blade or punch tool to remove a portion of the wart. The tissue sample is then sent to a laboratory for histopathological analysis, where it is examined for signs of viral infection and other abnormalities.

Results that Indicate Flat Warts

In cases of flat warts, the biopsy sample will typically show thickening of the outer layer of the skin (hyperkeratosis), as well as the presence of viral particles in the skin cells. The pathologist may also look for specific changes in the skin cells, such as koilocytosis, which is a sign of HPV infection. If the biopsy results confirm the presence of flat warts, the healthcare provider will discuss treatment options with the patient. If the biopsy results are negative for flat warts, the provider may investigate other potential causes of the skin lesions, such as eczema or psoriasis.

HPV Typing

HPV typing is a laboratory test that identifies the specific strain of human papillomavirus (HPV) responsible for the skin lesions. There are over 100 different strains of HPV, and certain strains are more likely to cause flat warts. HPV typing is typically performed using a sample of skin tissue or a swab of the affected area. The sample is then analyzed in a laboratory to determine which strain of HPV is present. This test can be useful in cases where the diagnosis is unclear or if the patient has a history of recurrent warts.

Results that Indicate Flat Warts

Flat warts are most commonly associated with HPV types 3, 10, 28, and 49. If the HPV typing test identifies one of these strains, it can help confirm the diagnosis of flat warts. In some cases, the test may identify multiple strains of HPV, which can indicate a more widespread infection. If the test results are negative for HPV, it may suggest that the skin lesions are not caused by a viral infection and that another condition, such as a benign skin growth, may be responsible. In such cases, further diagnostic testing may be needed.

Skin Scraping

Skin scraping involves gently scraping the surface of the wart with a small blade or spatula to collect a sample of skin cells. This sample is then examined under a microscope to look for signs of viral infection, such as the presence of HPV particles or changes in the skin cells. Skin scraping is a quick and simple procedure that can be performed in a healthcare provider’s office. It is often used as a preliminary test to help differentiate flat warts from other skin conditions, such as fungal infections or eczema.

Results that Indicate Flat Warts

When examining a skin scraping sample, healthcare providers look for specific changes in the skin cells that are characteristic of HPV infection, such as koilocytosis. These changes can help confirm the diagnosis of flat warts. If the skin scraping results do not show signs of HPV infection, the provider may consider other potential causes of the skin lesions, such as dermatitis or seborrheic keratosis. In some cases, additional tests, such as a biopsy or HPV typing, may be recommended to further evaluate the condition.

What if All Tests are Negative but Symptoms Persist?

If all diagnostic tests come back negative but the symptoms of flat warts persist, it is important to follow up with your healthcare provider. In some cases, the warts may be in an early stage or may not have produced enough viral particles to be detected by the tests. Your provider may recommend repeating the tests after a few weeks or trying a different diagnostic approach. Additionally, your provider may explore other potential causes of the skin lesions, such as benign skin growths or inflammatory skin conditions, and adjust the treatment plan accordingly.

Treatment Options for Flat Warts

Medications for Flat Warts

Salicylic Acid

Salicylic acid is a keratolytic agent that helps break down the outer layer of the skin. It is commonly used to treat flat warts by softening the skin and gradually peeling away the wart tissue.

Available in gel, liquid, or patch form, salicylic acid is often a first-line treatment due to its accessibility and effectiveness. It should be applied daily, with the wart soaked in warm water beforehand to enhance absorption.

Improvement is typically seen within a few weeks to a couple of months, depending on the size and number of warts. Consistent use is essential for optimal results.

Imiquimod

Imiquimod is an immune response modifier that stimulates the body’s immune system to fight the human papillomavirus (HPV), the virus responsible for flat warts.

Applied as a cream, it is usually reserved for warts that don’t respond to first-line treatments like salicylic acid. It is applied several times a week, with treatment lasting for weeks or months.

Results may take longer compared to other treatments, but Imiquimod is effective for persistent cases.

Cantharidin

Cantharidin, derived from the blister beetle, is a blistering agent applied by a healthcare provider. It causes a blister to form under the wart, which eventually lifts the wart off the skin.

This treatment is typically performed in a clinical setting and is often used for warts that do not respond to over-the-counter treatments. The wart is covered with a bandage, and a blister forms within 24 hours.

The wart usually peels off within a week, though multiple treatments may be necessary for complete removal.

Cryotherapy

Cryotherapy involves freezing the wart with liquid nitrogen, causing the tissue to die and fall off. It is a common and effective treatment, especially for flat warts on the face.

Performed in a healthcare setting, cryotherapy is often used when other treatments, like salicylic acid, have failed. Multiple sessions may be required, spaced a few weeks apart.

The wart typically falls off within a week or two after each session, though larger warts may need more treatments.

Trichloroacetic Acid (TCA)

Trichloroacetic acid is a stronger chemical peel than salicylic acid, used to burn off wart tissue. It is typically applied by a healthcare provider for resistant flat warts.

TCA is often used when other treatments have failed or for warts in sensitive areas, such as the face. The acid is applied directly to the wart, and the area may be bandaged.

Multiple treatments may be needed, with improvement usually seen within a few weeks.

Podophyllin

Podophyllin is a plant-based resin that stops cell division, preventing the wart from growing.

Applied by a healthcare provider, it is used for stubborn warts that haven’t responded to other treatments. The application is done once a week, and the wart is washed off after a few hours.

Several treatments may be required, with gradual improvement over weeks to months.

Bleomycin

Bleomycin, an anti-cancer drug, can be injected directly into the wart to kill the virus.

Typically reserved for severe or resistant warts, it is administered by a healthcare provider and may require multiple injections.

Warts gradually shrink and disappear over a few weeks, though this treatment is usually reserved for advanced cases due to potential side effects.

Laser Therapy

Laser therapy uses focused light to destroy the blood vessels feeding the wart, causing it to die and fall off.

Performed by a dermatologist or healthcare provider, laser therapy is often used for warts unresponsive to other treatments. Multiple sessions may be required.

The wart gradually shrinks and falls off after a few sessions, making it particularly useful for stubborn or deep-rooted warts.

Duct Tape Occlusion

Duct tape occlusion involves covering the wart with duct tape to suffocate it and stimulate the immune system to attack the wart.

This home remedy is sometimes recommended as a supplementary treatment. The duct tape is left on for several days, then removed, and the wart is soaked and filed down.

Gradual improvement may be seen over weeks or months, often in conjunction with other treatments like salicylic acid.

Topical Retinoids

Topical retinoids, derived from vitamin A, disrupt skin cell growth, helping to remove warts.

Prescribed by a healthcare provider, they are applied directly to the wart, typically once a day, for warts unresponsive to other treatments.

Gradual improvement is expected over weeks to months, making retinoids a good option for stubborn or recurrent warts.

Flat Warts Home Remedies

While medical treatments are often the most effective, some patients may wish to try home remedies as complementary treatments. These remedies are not guaranteed to work for everyone, but common options include:

1. Apple cider vinegar: Applied with a cotton ball, it works similarly to salicylic acid by peeling away the wart.
2. Tea tree oil: Known for its antiviral properties, it can be applied directly to reduce wart size.
3. Garlic: Crushed garlic is believed to have antiviral properties and is sometimes applied to warts.
4. Aloe vera: Known for its soothing properties, aloe vera can reduce irritation when applied to the wart.
5. Vitamin E: Applied topically, it may promote skin healing.
6. Banana peel: The inside of a banana peel is believed to help dissolve warts.
7. Castor oil: Thought to soften the skin and promote healing when applied to the wart.
8. Lemon juice: The acidity may help break down wart tissue over time.
9. Witch hazel: Known for its astringent properties, it may help dry out the wart.

Improving Flat Warts and Seeking Medical Help

Managing flat warts can be challenging, but combining medical treatments with home remedies may help. If you try home remedies, be patient, as results can take weeks to months. However, if your warts are not improving or are spreading, seek medical advice. Early treatment can prevent warts from becoming more difficult to treat.

Telemedicine offers a convenient way to consult with a healthcare provider from home. A telemedicine visit can help you get a proper diagnosis and discuss treatment options tailored to your needs. If your warts are persistent or painful, a healthcare provider can recommend more advanced treatments, such as cryotherapy or prescription medications.

Living with Flat Warts: Tips for Better Quality of Life

Living with flat warts can be frustrating, but there are steps you can take to manage the condition and improve your quality of life:

1. Keep the affected area clean and dry to prevent the spread of warts.
2. Avoid picking or scratching the warts, as this can cause them to spread.
3. Use over-the-counter treatments consistently for the best results.
4. Consider covering the warts with a bandage to reduce irritation and prevent spreading.
5. Maintain a healthy immune system through proper nutrition, exercise, and sleep to help your body fight off the virus.

Conclusion

Flat warts are a common but manageable skin condition caused by the human papillomavirus (HPV). While they can be stubborn, many treatment options are available, from over-the-counter medications to advanced procedures. Early diagnosis and treatment are crucial to prevent warts from spreading and becoming more difficult to treat.

If you’re struggling with flat warts, our telemedicine practice is here to help. Schedule a virtual consultation with one of our healthcare providers to discuss your symptoms and explore the best treatment options for you.

James Kingsley

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