Flat warts, known medically as verruca plana, are a common type of skin growth that many people encounter. These lesions are generally benign, meaning they are noncancerous and typically pose no serious health risk. Understanding the specific appearance of these growths is the first step toward identification. This guide provides a detailed visual description of flat warts, explaining their characteristic size, shape, and color to help distinguish them from other common skin conditions.
Distinctive Visual Features of Flat Warts
Flat warts earn their name from their noticeably smooth and subdued profile, which contrasts significantly with the rough, dome-shaped texture of common warts. These lesions are remarkably small, typically measuring between one and five millimeters across, roughly the size of a pinhead or a small sesame seed. Their minute size can sometimes make them difficult to notice at first glance, especially if they are few in number.
The shape of an individual flat wart is usually round or oval, and its surface is consistently flat or only very slightly raised above the surrounding skin. This growth pattern occurs because the viral infection causes the skin cells to multiply horizontally within the top layer of the epidermis, rather than pushing outward in a prominent lump. They often present as subtle changes in the skin texture rather than as distinct bumps.
The color of flat warts is another defining feature, often blending in closely with the person’s natural skin tone. They may appear flesh-colored, light brown, pinkish, or sometimes a yellowish-brown hue. This subtle coloration, combined with their flat shape, contributes to their nickname, “plane warts.”
A helpful diagnostic clue is their tendency to appear in clusters or groups, often numbering from twenty up to a hundred individual lesions in a single area. Flat warts frequently arrange themselves in straight lines, a phenomenon called the Koebner phenomenon. This linear pattern often follows a scratch mark or a line of trauma on the skin, demonstrating how the virus can spread along a break in the skin barrier.
How Flat Warts Develop and Spread
The development of flat warts is directly linked to infection by the Human Papillomavirus (HPV), specifically certain low-risk strains like types 3, 10, 28, and 49. These particular strains of the virus target the epithelial cells of the skin, triggering an accelerated, yet benign, growth of these cells. The infection causes the skin to thicken, forming the characteristic flat lesion.
Transmission of the virus occurs through direct skin-to-skin contact with an infected person or by touching surfaces that have been contaminated with the virus. The virus needs a break in the skin barrier, such as a cut, scratch, or abrasion, to successfully initiate an infection. People with compromised skin integrity are more susceptible to acquiring the virus.
The process of autoinoculation is a common way these warts spread from one area of the body to another on the same person. Actions like scratching an existing wart or shaving can create micro-traumas in the skin, effectively transferring the virus to a new site.
Flat warts are frequently found on the face and neck, particularly in children and adolescents, which is why they are sometimes called “juvenile warts.” They are also common on the back of the hands, arms, and legs, especially in women who shave these areas. The repeated trauma from shaving creates small entry points for the virus, leading to the development of new warts along the path of the razor.
Options for Managing and Treating Flat Warts
In many cases, flat warts will spontaneously disappear over time as the body’s immune system recognizes and clears the viral infection. This natural resolution can take months or even a few years. Treatment is available if the warts are numerous, spreading rapidly, or causing cosmetic concern. Medical intervention aims to remove the visible lesions or stimulate an immune response against the underlying virus.
Common treatment options include the application of topical medications that cause controlled irritation or peeling of the skin, or procedures performed in a clinical setting.
Topical and Immune Treatments
- Prescription-strength topical retinoids, such as tretinoin, work by promoting the turnover of skin cells, which helps shed the infected layers.
- Salicylic acid, available over the counter, can be used to gradually peel away the wart tissue.
- Immune-modulating creams, like imiquimod, work by encouraging the local immune cells to attack the virus that causes the warts.
Clinical Procedures
Procedures such as cryotherapy involve freezing the lesions with liquid nitrogen to destroy the infected tissue.
It is important to consult a healthcare provider, such as a dermatologist, for an accurate diagnosis before starting any treatment. Many other skin conditions can mimic the appearance of flat warts. A professional can confirm the diagnosis and recommend the most appropriate and effective treatment plan. The choice of therapy often depends on the location and number of the warts and the patient’s age and skin type.