Symptoms
Plantar warts are hard, rough, granular and benign skin growths that appear on the sole of the foot. They are surrounded by a cornified ring. Plantar warts occur mainly on the ball of the foot and on the heel. They grow towards the inside and have a thickened horny layer on the surface. Pain may occur when standing or walking, as the wart feels like a thorn or a stone in the shoe. The black dots in the wart are thrombosed (blocked) blood vessels. Plantar warts occur more frequently in children and adolescents and in immunosuppression.
Causes
The cause of the disease is infection of the keratinocytes in the epidermis of the skin with various types of human papillomaviruses (mainly HPV 1, 2, 4, 27, and 57). The DNA viruses penetrate the tissues through small injuries, softened skin or cracks. The infection leads to hyperplasia (cell proliferation), thickening and hyperkeratosis of the epithelium. Due to the pressure of the body weight, the wart is pressed into the dermis and cannot grow outward. The exfoliated skin scales are infectious. Transmission typically occurs in swimming pools, communal showers, locker rooms, gyms, or within the family. Walking barefoot is an important risk factor. Less commonly, the viruses are also passed from person to person. Those who have had a wart before are more susceptible.
Diagnosis
Diagnosis is made based on the patient’s history and physical examination. Other skin conditions, such as corns, must be ruled out. These, unlike plantar warts, do not have black spots. Warts also disrupt the structure of the papillary ridges.
Non-drug treatment
A first option is observant waiting. Plantar warts can disappear on their own over time – but this can take up to two years (!) After this period, two-thirds of warts are usually gone. However, warts can cause pain, they are contagious and cosmetically disturbing. Warts are destroyed by physical methods. One common method is icing (cryotherapy). In this process, an applicator is saturated with liquid nitrogen, resulting in very low temperatures well below freezing. The applicator is held on the wart for the prescribed time. After about one to two weeks, the frozen tissue can be peeled off. The treatment may need to be repeated. Other substances such as dimethyl ether and propane are also used in self-medication. Warts can also be ablated or excised with minor surgery. Methods used include curettage or laser treatment. Pressure sore patches or rings made of foam can be applied to relieve the pressure soreness.
Drug treatment
The most common treatment methods include application of salicylic acid and icing. According to the literature, both methods are about equally effective (Cockayne et al, 2011). Treatment may not be successful the first time and may need to be repeated. Some warts also prove to be persistent. Generally, therapy is more effective if the top horny layer is removed first. The active ingredients used include (selection): Salicylic acid has keratolytic properties. It dissolves the infected skin over time and also has an irritant effect, which stimulates the immune system. Acids such as trichloroacetic acid, monochloroacetic acid, acetic acid, lactic acid or formic acid dissolve or soften the diseased skin and are applied locally, for example with a brush or a wart pencil. If the agents cannot be applied with pinpoint accuracy, protection of the surrounding skin with an ointment is possible. Cytostatic agents such as 5-fluorouracil are approved for treatment. The effects are based on inhibition of DNA and RNA synthesis. The use of bleomycin is also mentioned in the literature (off-label). Retinoids such as adapalene are also effective according to some studies. Adapalene has been applied under occlusion (Gupta & Gupta, 2015). It is used without official regulatory approval (off-label). In alternative medicine, Thuja is a popular remedy, for example, in the form of a tincture.
