Warts are small, rough skin growths caused by the human papillomavirus (HPV), and they have a few telltale features that set them apart from other bumps. The most reliable visual clue is a scattering of tiny black dots within the growth, which are actually clotted blood vessels feeding the wart from below. Knowing what to look for depends partly on the type of wart, since they vary quite a bit in shape, texture, and location.
Common Warts on Hands and Fingers
Common warts are the type most people picture. They’re small, grainy growths that feel rough to the touch, typically appearing on the fingers or backs of the hands. They range from pinhead-sized to about 10 millimeters across and are usually dome-shaped and skin-colored. The surface has a bumpy, almost cauliflower-like texture rather than being smooth.
The signature feature is those tiny black dots, sometimes called “wart seeds.” They aren’t seeds at all. They’re small blood vessels that have clotted inside the wart’s structure. If you look closely at a suspicious bump and see a sprinkling of dark pinpoints, that’s a strong indicator you’re dealing with a wart rather than a callus or other growth. Calluses, by comparison, have smooth, even skin lines running through them, while warts interrupt the normal fingerprint-like ridges of your skin.
Plantar Warts on the Feet
Plantar warts grow on the soles of the feet, and because you’re constantly walking on them, they get pushed inward rather than growing outward. This makes them easy to confuse with calluses. The key difference: plantar warts have that same rough, cauliflower-like texture and may contain black specks. A callus is smooth with intact skin lines.
These warts can be painful, particularly when you press on them from the sides rather than pushing straight down. That lateral squeeze test is a quick way to distinguish a plantar wart from a simple callus. Plantar warts also tend to have a well-defined border, whereas calluses blend gradually into the surrounding skin.
Flat Warts
Flat warts look completely different from common warts and are easy to miss. They’re smooth, only slightly raised, and tiny, between 1 and 5 millimeters across (no bigger than a pinhead). They can be yellowish-brown, pink, or skin-colored, and their surface is flat rather than bumpy. You might not even notice the slight elevation unless you run a finger across them.
The biggest giveaway is that flat warts almost always appear in clusters. A single flat bump probably isn’t a flat wart. But a patch of a dozen to a hundred tiny, smooth, slightly raised spots, often on the face, forehead, or along the shins, fits the pattern perfectly. They sometimes spread in a line along a scratch or area of skin irritation, because the virus can spread through minor breaks in the skin.
Filiform Warts
Filiform warts have a distinctive shape that’s hard to confuse with anything else once you know what to look for. They grow as long, narrow, flesh-colored stalks that stick out from the skin surface. They tend to appear around the eyelids, face, neck, or lips, either singly or in small groups. Because they’re thread-like rather than dome-shaped, they look more like tiny fingers of skin than typical bumps.
Genital Warts
Genital warts appear in the moist tissues of the genital area and can look like small, skin-colored bumps or swellings. They may be flat or slightly raised, and when several grow close together they can take on a cauliflower-like shape. Their color may match the surrounding skin or differ slightly. In people with weakened immune systems, they can multiply into larger clusters. Genital warts are caused by different HPV strains than the ones responsible for hand or foot warts, and they’re transmitted through sexual contact.
How Warts Differ From Similar Growths
Several other skin conditions look enough like warts to cause confusion.
Seborrheic keratoses are brown, black, or yellowish growths that are often mistaken for warts. The difference is that seborrheic keratoses have a waxy, “stuck-on” appearance, as if you could peel them off. They’re more common in middle-aged and older adults and tend to appear on the torso, face, and shoulders. They don’t have the grainy texture or black dots that warts do.
Molluscum contagiosum produces pink or flesh-colored bumps that can appear anywhere on the skin. These bumps are smooth and dome-shaped, and the hallmark is a small dimple or indentation in the center of each one. Warts lack this central dimple. Like warts, molluscum is caused by a virus and is contagious, but the bumps have a pearly, waxy quality that warts don’t share.
Skin tags are soft, floppy pieces of skin that hang from a thin stalk. Unlike filiform warts, which are firm and project outward, skin tags are soft to the touch, painless, and don’t have any rough texture.
The Black Dot Test
If you’re trying to decide whether a bump is a wart, the single most useful thing to look for is the pattern of tiny dark dots inside the growth. These clotted blood vessels are present in most common and plantar warts and are visible to the naked eye, especially if you gently pare away any thickened skin on top (this is how clinicians often confirm the diagnosis in office).
Another reliable check is whether the normal skin lines, your fingerprints or the ridges on the sole of your foot, pass through the bump or go around it. Warts disrupt those lines. Calluses and other thickened skin preserve them.
When a Growth Needs Professional Evaluation
Most warts are harmless and many resolve on their own, but certain features warrant a closer look by a dermatologist. A growth that changes rapidly in size, bleeds without being picked at, or has irregular coloring (especially on the hands or feet) should be examined. In rare cases, skin cancers can mimic the appearance of a wart. Case reports in dermatology literature have documented growths initially treated as warts that turned out to be skin cancer on closer inspection, which underscores the value of getting a biopsy for any lesion that looks atypical or doesn’t respond to standard wart treatment after several months.
Growths that are unusually large, have an uneven border, or appear in someone with a weakened immune system also deserve professional evaluation rather than home treatment.