OVERVIEW

What is plantar wart?

Plantar wart is a skin disease caused by infection with human papillomavirus (HPV) and is a type of common wart. It occurs on the soles of the feet, especially in the metatarsal and toe areas (one or both soles and toes), hence the name plantar wart^[1].

Since plantar warts differ in appearance from common warts in other areas, people often regard them as a separate condition.

Located on the soles of the feet and subjected to prolonged pressure, plantar warts develop a yellowish, callus-like layer of keratin on the surface. Some may also show scattered small black dots (actually caused by ruptured tiny blood vessels)^[1].

Plantar warts most commonly appear in weight-bearing areas of the foot (such as the ball near the big toe). Trauma, friction, and sweating are common triggers for plantar warts^[1,2].

Are plantar warts common?

Plantar warts are common, accounting for 34% of all skin warts. This means that out of 100 patients with skin warts, about 34 have plantar warts^[3]. They can occur at any age^[1].

There is no precise epidemiological data on skin warts, but overall, wart diseases (including common warts, genital warts, etc., caused by HPV infection) have an incidence rate of approximately 3 per 1,000 in the general population^[4]. Simply put, out of every 1,000 people, about 3 may have a wart condition.

SYMPTOMS

What are the symptoms of plantar warts?

1. Skin manifestations:
   A plantar wart initially appears as a pinhead-sized papule, which gradually enlarges into a light yellow or brownish-yellow, hard, slightly raised plaque with a rough surface and clear boundaries from the surrounding normal skin.

   Due to its contagious nature, it may appear as a single lesion or multiple lesions caused by self-infection, and may even merge into clusters.

   Because it is located on the sole of the foot and subjected to prolonged pressure, a light yellow, callus-like layer of keratin forms on the surface. Some may also show scattered small black dots (caused by ruptured tiny blood vessels).

2. Sensory manifestations:
   There are usually no subjective symptoms, but pain may be felt when pressing firmly or during normal weight-bearing on the foot.

3. Other manifestations:
   If the surface keratin is removed, concentric rings of keratin surrounding a "soft core" may be visible, along with possible bleeding spots (also caused by ruptured small blood vessels).

Can plantar warts become malignant?

The viruses causing plantar warts are mostly low-risk types and generally do not become malignant. However, modern medicine has shown that any infection caused by human papillomavirus (HPV) has the potential to become cancerous, so there are rare reports of malignant transformation leading to verrucous carcinoma ^[1].

Can plantar warts spread and cause genital warts or flat warts?

No.

Although they are all related to human papillomavirus (HPV), they are caused by different subtypes. HPV has over 150 subtypes.

Most common warts (plantar warts are a type of common wart) are caused by HPV-1, 2, 4, 27, or 57, flat warts are mostly caused by HPV-3 or 10, and genital warts are mainly caused by HPV-6 or 11.

Which department should you visit for plantar warts?

Plantar warts are typically treated in the dermatology department.

CAUSES

What causes plantar warts? What are the triggers?

1. Causes:

   Plantar warts are caused by human papillomavirus types 1, 2, and 4 (HPV 1, 2, 4). After HPV infection, abnormal cellular immune function allows the virus to invade the skin of the soles, multiply, and cause abnormal growth of skin cells, eventually forming raised growths on the skin's surface.

2. Triggers:

   Foot trauma, friction, and sweating: Daily pressure on the soles, excessive sweating, and friction leading to thickened keratin layers can all trigger the development of plantar warts.

Are plantar warts hereditary?

No. Plantar warts are caused by HPV infection, and there is currently no evidence to suggest they can be passed down genetically.

Are plantar warts contagious?

Yes.

Human papillomavirus (HPV) can spread to others through direct contact or environmental exposure, causing common warts. Plantar wart patients may also self-infect, leading to warts in other areas.

DIAGNOSIS

What tests are needed for plantar warts?

1. Generally, no special tests are required. An experienced dermatologist can diagnose it through visual observation.

2. For confirmation, some laboratory tests may be conducted.

   • Dermoscopy: A non-invasive examination of the skin in the wart area, preferred for cases where visual diagnosis is unclear. It may reveal brown or dark brown linear or dotted bleeding signs in the center of the lesion^[1].
   • Virus detection and identification: Testing the papule tissue for the presence of HPV virus can confirm the diagnosis.
   • Clinical immunological tests: Assess whether the patient's immune system has issues, such as a reduction in immune cells.

Which diseases have similar symptoms to plantar warts?

Due to similar symptoms (thickening of the plantar keratin layer), plantar warts may be confused with conditions like corns and calluses, requiring differentiation.

1. Corns: Corns are usually caused by pressure on the soles or between toes, occurring in similar locations as plantar warts. They are often solitary and tender. Corns typically appear as a transparent yellow ring surrounding a small, hard core, resembling a chicken's eye. The skin lines disappear at the center, and removing the surface keratin does not cause bleeding.

2. Calluses: Calluses result from long-term friction, leading to thickened keratin. They usually appear on the forefoot or heel as pale-yellow, poorly defined patches with clear skin texture and are generally painless.

TREATMENT

Can plantar warts heal on their own? If I suspect I have a plantar wart, do I need to see a doctor?

It is best to seek medical attention promptly for diagnosis and treatment by a doctor. Here’s why:

1. Although plantar warts may resolve on their own, the process can take a long time. Common warts may naturally disappear, with a five-year spontaneous clearance rate of up to 90%. This means 90% of patients with common warts may recover on their own in about five years^[1].

2. During the growth of plantar warts, pain and discomfort may occur, along with abnormal keratin hyperplasia on the foot, which can interfere with daily life.

3. Plantar warts are also contagious and can spread to other parts of the body or to other people.

How should plantar warts be treated?

Since there is no specific medication for HPV, treatment for plantar warts focuses on localized therapies. After diagnosis by a doctor, follow their recommended treatment plan. The most common standard treatments include the following two methods, which you can briefly understand:

1. Physical therapy

   • Cryotherapy (liquid nitrogen) Repeated freezing causes the affected tissue to necrotize and fall off. Typically, 2–3 or more sessions are required. The first session does not freeze too deeply, and multiple sessions help control the depth more precisely, reducing the risk of scarring. However, cryotherapy often leads to pigmentation, so patients concerned about foot aesthetics should consider this carefully^[1].
   • Laser therapy This directly targets the base of the wart tissue, creating fissures in the underlying dermis and causing the wart to fall off. It achieves treatment goals while minimizing damage to the dermis, offering significant clinical advantages^[1].

2. Topical medications

   • Salicylic acid Topical salicylic acid helps the affected skin peel off and may stimulate local immune responses to clear the virus. Products containing 17%–50% salicylic acid are typically used^[1].

   • Retinoids Topical retinoid creams or tazarotene gel can inhibit abnormal proliferation and differentiation of wart cells, effectively controlling wart growth. However, they may cause side effects such as skin cracking, dryness, and itching^[1].

Do plantar warts require hospitalization?

No. Physical therapies can be performed in outpatient clinics. For patients with multiple lesions, treatment can be administered in batches (as assessed by the doctor)^[1]. For medication treatments, simply follow the doctor’s instructions at home.

Do plantar warts require follow-up visits?

Follow-up is unnecessary unless the warts recur.

Can plantar warts be completely cured? Will they recur?

Plantar warts can be cured, but this is not absolute.

HPV can remain latent in the body. If the immune system weakens or other factors reactivate the virus, plantar warts may recur. Additionally, reinfection can also lead to new warts.

Will plantar warts leave scars after treatment?

Whether scars form depends on the treatment method and the size of the warts. Any treatment that damages the dermis can cause scarring.

For example, cryotherapy may leave scars if the freezing depth is excessive and affects the dermis. Improper use of salicylic acid (in terms of duration or concentration) can also cause scarring. Larger warts may also result in scarring.

Therefore, it is recommended to seek treatment at a reputable dermatology clinic and avoid relying on unverified advertisements or folk remedies.

DIET & LIFESTYLE

Will plantar warts recur after self-trimming?

The likelihood of recurrence is very high.

When patients trim the wart themselves, they usually stop once it's level with the surrounding skin, starts bleeding, or becomes painful. However, this often only removes part of the wart (if the lesion feels harder than the surrounding skin when pressed, it indicates remaining tissue), and the residual portion can continue to grow.

Additionally, self-trimming or visiting informal pedicure shops may lead to secondary infections. Therefore, it's best to seek treatment at a proper medical facility.

What precautions should plantar wart patients take in daily life?

1. Always follow medical instructions and use medications strictly according to the prescription and doctor's guidance. If other symptoms appear, stop medication immediately and consult a doctor.
2. Ensure adequate sleep and try to avoid staying up late.
3. Maintain proper hygiene for the affected area: use appropriate water temperature for cleaning and avoid irritating cleansers like alkaline soap.
4. Wear loose, breathable shoes to prevent pressure on the soles. Keep personal footwear separate to avoid mixing with others'. Shoes can be disinfected with 75% medical alcohol spray or soaked in disinfectant for over ten minutes before scrubbing, and should be frequently sun-dried. Socks can be sterilized by boiling in hot water before air-drying.
5. Avoid factors that may hinder skin recovery, such as skin damage, high temperatures, humidity, and excessive heat.
6. Exercise regularly to boost immunity and enhance antiviral capabilities.
7. Since plantar wart treatment is lengthy, persistence is crucial—do not give up halfway.

What dietary precautions should plantar wart patients follow?

1. Maintain a light diet, consume fresh fruits and vegetables for sufficient vitamins, and drink plenty of water to accelerate metabolism ^[1].
2. It's best to avoid alcohol during medication treatment.

PREVENTION

Can plantar warts be prevented? What are the preventive measures for plantar warts?

Yes, they can be prevented.

1. Pay attention to protection in daily life to avoid injuries and skin damage. Proper and timely treatment should be given to any damaged skin.
2. Disinfect shared household items regularly using 75% medical alcohol or disinfectants. Clothes and shoes should be frequently exposed to sunlight to prevent cross-infection. If family members or friends have common warts or plantar warts, advise them to seek early treatment.
3. Patients with plantar warts should avoid scratching and seek timely treatment to prevent self-infection or transmission to others. Recurrence is possible after curing plantar warts. Avoiding foot injuries, excessive friction, and sweat soaking may help reduce the recurrence of plantar warts.
4. People who experience prolonged foot pressure should pay attention to labor protection to prevent injuries^[1].