Corns are common skin growths that represent areas of thickened, hardened skin that develop in response to repeated pressure and friction on the foot. This hardening, known as hyperkeratosis, is the body’s natural defense mechanism, creating a protective layer to shield underlying tissues from mechanical stress. Corns are a physical reaction to external forces, typically caused by ill-fitting shoes or structural foot deformities.
What a True Corn Looks Like
A true corn is a small, concentrated area of skin thickening that is typically round and raised. Unlike a general callus, a corn features a dense, central core that is forced inward, often described as having a cone-like shape. The visible surface of this core may appear translucent, yellowish, or waxy, surrounded by an area of softer skin.
This inwardly directed core causes the characteristic pain associated with corns. When pressure is applied, the hard center acts like a nail, pressing down onto the sensitive nerve endings beneath the skin. Corns are most commonly found on the tops or sides of the toes, or between the toes, areas prone to friction.
The Significance of a Black Dot
True corns do not typically contain black dots in the center. The presence of small, dark pinpoints is a distinguishing physical sign that points toward an entirely different condition: a plantar wart, or verruca. These dark spots are not part of the corn’s thickened skin structure. Instead, the black dots represent tiny blood vessels that have clotted, often called thrombosed capillaries. Warts are caused by an infection with the Human Papillomavirus (HPV), which requires a blood supply to grow. When the top layer of a wart is pared down, these damaged, clotted capillaries become visible, indicating a viral origin rather than one based on friction.
Distinguishing Corns from Plantar Warts
Differentiating between a corn and a plantar wart is necessary because their causes and required treatments are fundamentally different. Corns are a mechanical issue stemming from pressure, while warts are a biological issue caused by a contagious virus.
A primary way to distinguish the two is by evaluating the source of pain. A corn typically causes sharp, stabbing pain when direct pressure is applied straight down onto the lesion, pushing the central core inward. Conversely, a wart is more likely to cause pain when the area is squeezed from the sides, which compresses the nerve endings and the wart’s core. This lateral compression test is a helpful diagnostic tool.
Another key difference is the appearance of the skin lines, or striations, across the lesion. A corn is simply thickened skin, so the normal parallel skin lines of the foot usually continue uninterrupted across its surface. In contrast, a wart is a growth caused by a virus that disrupts the normal skin pattern, so the skin lines often stop and go around the lesion. Warts may also have a rough, grainy, or cauliflower-like texture. Corns are not contagious, but warts are, meaning a wart can spread and form clusters known as mosaic warts.
When to Seek Professional Help
While many corns and warts can be managed with home care, there are several instances when a consultation with a podiatrist or dermatologist is necessary. If the lesion is causing intense pain, bleeding, or shows signs of infection like redness, swelling, or discharge, professional care should be sought promptly.
Individuals with underlying health conditions, such as diabetes, poor circulation, or a weakened immune system, should always consult a specialist before attempting any self-treatment. For these patients, even a minor cut or abrasion from trying to remove a lesion can lead to a serious foot ulcer or infection. A professional can provide an accurate diagnosis and safely remove the lesion or recommend the appropriate medical treatment.