Warts are small, rough skin growths caused by human papillomavirus (HPV) that typically appear as firm, raised bumps with a grainy or cauliflower-like texture. Their exact look varies quite a bit depending on the type of wart and where it shows up on your body, but most share a few telltale features: a thickened surface, a well-defined border, and tiny dark specks that many people call “seed” dots. Understanding what each variety looks like can help you tell a wart apart from a callus, a corn, or something that warrants a closer look from a dermatologist.
Common Warts
The most familiar type is the common wart, known in medical terminology as verruca vulgaris. These usually pop up on the fingers, backs of the hands, and around the nails, though they can show up almost anywhere. A classic common wart is a dome-shaped, rough bump that rises above the surrounding skin. The surface often has a bumpy, papillomatous texture, and when examined closely it can display tiny finger-like projections, giving it that signature “cauliflower” look. Common warts range in color from skin-toned to grayish-white or slightly yellowish-brown.
Under magnification, common warts reveal patterns that are useful for identification. Dermatologists using a dermoscope can see hairpin-shaped or dotted blood vessels running through the wart, along with small bleeding spots surrounded by a whitish ring, a pattern sometimes called a “frogspawn” appearance.1PubMed Central. Dermoscopy Features of Cutaneous Warts You don’t need a dermoscope to spot a common wart, but knowing that these vascular details exist helps explain why warts sometimes bleed easily when scratched or picked at.
Plantar Warts
Plantar warts grow on the soles of the feet, and because you walk on them, they get pushed inward rather than rising above the skin. Instead of a dome, you see a flat or slightly recessed patch of thickened skin, often with a well-defined border. Most plantar warts appear on the sole itself or on the toes, and the majority are single lesions rather than clusters.2PubMed Central. Clinical Characteristics of Plantar Warts and Association With BMI: A Retrospective Case Series Study The surface tends to be yellow or brown, and when you look closely or pare away the top layer of dead skin, you can often see tiny dark dots, which are the hallmark vascular sign of a wart.
Not all plantar warts feel the same, and the reason traces to which strain of HPV is responsible. Deep, painful plantar warts (sometimes called myrmecia) are associated with HPV type 1, while superficial, relatively painless plantar warts, often appearing in a mosaic pattern of small clustered lesions, are associated with HPV type 2.3PubMed. Two anatomoclinical types of warts with plantar localization: specific cytopathogenic effects of papillomavirus If your plantar wart feels like stepping on a pebble every time you put weight on it, you’re likely dealing with the deeper HPV-1 variety. If you notice a cluster of tiny, flatter lesions that don’t hurt much, the mosaic type is more probable.
Flat Warts
Flat warts, or verruca plana, look quite different from the bumpy common wart. They are small, smooth-topped, slightly raised growths, usually only a millimeter or two above the skin surface. They tend to be skin-colored, pinkish, or light brown, and their smooth texture makes them easy to overlook early on. Flat warts favor the face, forehead, and backs of the hands, and they often appear in large numbers, sometimes dozens at a time.
One reason flat warts are worth knowing about is a phenomenon called the Koebner response, where irritation or trauma to the skin causes new warts to sprout along the line of injury. A case report documented this happening when a patient applied crushed garlic to a facial flat wart as a home remedy, and the irritation from the garlic triggered a beaded line of new warts along the damaged skin, where HPV from the original lesion spread into the freshly injured tissue.4Wiley Online Library. Topical garlic treatment for verruca plana triggers Koebner phenomenon: A case report This is a good reason to avoid picking at, scratching, or aggressively treating flat warts on your own, especially on the face. Irritation can make them multiply rather than disappear.
Genital Warts
Genital warts, or condylomata acuminata, are soft, flesh-colored or pinkish growths that appear in the anogenital area. Their shape varies widely. Some look like small, flat bumps; others resemble tiny cauliflower-like clusters; and some are smooth, dome-shaped papules. They can appear on the external genitalia, around the anus, or on surrounding skin. About 90 percent of genital wart cases are caused by HPV types 6 and 11, which are considered low-risk strains because they rarely lead to cancer.5PubMed Central. Genital warts: a comprehensive review
What makes genital warts tricky to identify on your own is that their appearance is quite variable. A study that examined genital wart lesions in detail found significant differences in size, surface texture, and color across specimens, even though nearly all tested positive for HPV types 6 or 11. Standard histopathologic criteria for identifying genital warts were present in only about 71 percent of specimens examined, meaning even under a microscope some genital warts don’t look “textbook.”6JAMA Dermatology. A Morphologic, Pathologic, and Virologic Study of Anogenital Warts in Men If you notice any new, persistent bumps in the genital area, a healthcare provider is the right person to evaluate them, because visual identification alone isn’t always reliable.
Periungual and Subungual Warts
Warts that grow around or underneath fingernails and toenails are called periungual (around the nail) or subungual (under the nail). They start out as small, rough bumps near the nail fold or cuticle and can gradually grow to lift, distort, or crack the nail plate. These warts are stubborn and often painful because of their location, and they can be difficult to treat since the nail itself shields the wart from topical therapies.
Periungual warts are commonly seen in people who bite their nails or pick at cuticles, since the broken skin creates an entry point for HPV. The surface of the wart looks similar to a common wart, with a rough, papillomatous texture, but the nail involvement distinguishes it. In severe cases, the wart can push the nail upward and cause permanent nail deformity if left untreated for a long time.7PubMed. Complete resolution of recalcitrant periungual/subungual wart with recovery of normal nail following “prick” method of administration of bleomycin 1% Fortunately, normal nail regrowth is possible once the underlying wart is resolved.
What the Black Dots Actually Are
Those small dark specks inside a wart are one of the most recognizable visual clues that you’re looking at a wart and not just a callus. Many people call them “seeds,” but warts don’t contain seeds. The dots represent tiny blood vessels or areas of hemorrhage within the wart tissue. The main vascular feature seen under magnification is dilated and thrombosed (clotted) vessels sitting within the upper layer of the skin.8PubMed Central. A Dermoscopic Study of Cutaneous Warts and Its Utility in Monitoring Real-Time Wart Destruction by Radiofrequency Ablation
There has been some debate about exactly what produces the visible black dots, particularly in plantar warts. One study found that the dots correlate primarily with tiny hemorrhages trapped in the top layer of skin (the stratum corneum) rather than with clotted blood vessels deeper in the dermis.9Journal of the American Academy of Dermatology. Black dots in palmoplantar warts—challenging a concept: A histopathologic study Regardless of the exact mechanism, the practical takeaway is the same: dark specks inside a rough skin bump are a strong visual indicator that you’re dealing with a wart.
When a plantar wart suddenly turns uniformly black, that’s a different story. Biopsy studies have shown that a wart turning completely black can indicate blood clots and tissue breakdown throughout the lesion, with thrombosis of both superficial and deeper blood vessels and degeneration of the surrounding cells.10JAMA Dermatology. Plantar Warts Recently Turned Black: Clinical and Histopathologic Findings This can happen spontaneously as the body’s immune system attacks the wart, or after treatments like cryotherapy. A wart turning black often signals that it’s dying, but it’s worth having a provider confirm this, particularly if the change appeared without any treatment.
Telling a Wart From a Callus or Corn
On the feet especially, warts can look a lot like calluses or corns, and the confusion is understandable. All three involve thickened, hardened skin on weight-bearing areas. But there are several visual differences that help separate them, even without medical tools.
A plantar wart disrupts the normal skin lines (the tiny ridges and grooves on your sole). If you look closely, the skin lines go around a wart rather than running through it. A callus, by contrast, preserves the normal skin line pattern. Warts also have those characteristic dark dots; calluses don’t. When a dermatologist examines these lesions with a dermoscope, the differences become even clearer. Warts consistently show dark red or black dots in the tissue. Corns show a translucent central core, and calluses show a uniform, opaque thickening without any vascular pattern.11PubMed Central. Dermoscopic Findings in Clinically Diagnosed Cases of Plantar Warts, Corns, and Calluses: A Cross-Sectional Study These dermoscopic differences are consistent enough that they serve as a reliable diagnostic tool when the naked eye can’t tell the difference.12British Journal of Dermatology. Differential diagnosis of plantar wart from corn, callus and healed wart with the aid of dermoscopy
A simple at-home test: pinch the lesion from side to side. Warts tend to hurt when squeezed laterally. Calluses and corns tend to hurt when pressed directly downward. It’s not a perfect test, but it’s a useful quick check.
Why Some Warts Look Darker Than Others
Warts can appear darker than the surrounding skin, and not just because of the black dot phenomenon. Some warts become genuinely pigmented, especially in people with darker skin tones. Research into pigmented warts has found that the darkening comes from two sources working together: melanocytes (the cells that produce skin pigment) getting disrupted and releasing excess melanin into surrounding cells, and the accumulation of dense protein inclusions inside the wart cells themselves.13PubMed Central. Pigmented viral warts: a clinical and histopathological study including human papillomavirus typing The combination of these factors makes some warts appear brown or even nearly black.
This matters because a pigmented wart on the hand or foot can be mistaken for a mole, a melanocytic nevus, or even melanoma. If a dark spot on your skin has a rough, grainy surface and those characteristic dark dots when you look closely, it’s far more likely to be a pigmented wart. But any dark lesion that changes rapidly, has irregular borders, or bleeds without provocation should be checked by a dermatologist to rule out something more serious.
What a Wart Looks Like Under the Microscope
If a wart is biopsied, the pathologist sees a very specific pattern. The tissue shows finger-like projections of thickened skin growing outward, lined by cells with a distinctive feature called koilocytotic atypia, which means the cell nuclei are wrinkled and dark, each surrounded by a clear halo.14PubMed Central. Histopathological Study of Verrucous Lesions and its Mimics These koilocytes are the microscopic fingerprint of HPV infection. They form when the virus hijacks normal skin cells and alters their structure as it replicates.
Biopsies aren’t usually needed for straightforward warts. Dermatologists can diagnose most warts just by looking at them, especially with dermoscopy. But when a growth is ambiguous or isn’t responding to treatment as expected, a biopsy provides definitive confirmation and can rule out conditions that mimic warts, such as seborrheic keratoses, squamous cell carcinomas, or other verrucous lesions that look bumpy on the surface but have very different biology underneath.
How Dermoscopy Predicts Treatment Response
An interesting clinical development is the use of dermoscopy not just to identify warts, but to predict how well they’ll respond to treatment. Research has found that certain visual features under the dermoscope are associated with better outcomes from cryotherapy (freezing). Warts with heavy surface scaling, well-defined borders, and visible dots responded much better to freezing than warts with minimal scaling and smooth surfaces. Specifically, marked surface scales were observed about six and a half times more often in warts that fully cleared after cryotherapy compared to warts that didn’t respond. Common warts responded best when they showed strong vascularity and thick scales, while plantar warts responded best when the surrounding skin showed redness.15PubMed Central. Predictive dermoscopic features of cryotherapy treatment response in cutaneous warts
For you as a patient, this means that the visual appearance of your wart may influence the treatment approach your dermatologist recommends. A thick, well-defined wart with visible vasculature is a good candidate for freezing. A smooth, poorly defined lesion might do better with a different method, or might need more sessions.
Warts in People With Weakened Immune Systems
Warts look and behave differently in people whose immune systems are compromised, whether from HIV/AIDS, organ transplant medications, or other immunosuppressive therapies. In these patients, warts tend to be more numerous, larger, and harder to get rid of. They may cover large areas of the hands, feet, or face, and individual warts may grow to sizes rarely seen in otherwise healthy people. Standard treatments frequently produce poor results in this population because the body’s immune system isn’t able to do its share of the work.16PubMed Central. Treatment of Multiple Recalcitrant Warts in an Immunocompromised Patient Using Purified Protein Derivative (PPD) Injection: A Case Report
This makes sense in the broader context of how the immune system interacts with HPV. In healthy people, the immune system clears most HPV infections without the person ever knowing they had one, driven primarily by a strong localized cellular immune response.17PubMed. Immune responses to human papillomavirus That’s why many warts eventually go away on their own, often within a year or two, though the timeline varies widely. When immunity is suppressed, that natural clearance stalls, and warts persist and spread. People on immunosuppressive medications after organ transplants, for example, frequently develop widespread warts that resist multiple rounds of treatment.18PubMed. Immunology of human warts
When a Wart Isn’t Just a Wart
Most warts are harmless nuisances, but a few visual red flags should prompt a dermatologist visit rather than a do-it-yourself approach. A growth that bleeds repeatedly, grows rapidly, has an irregular or asymmetric shape, or develops ulceration deserves professional evaluation. Squamous cell carcinoma, in particular, can sometimes present with a verrucous (wart-like) surface, and it shows up in the same sun-exposed areas where common warts appear. In immunosuppressed patients the overlap is even more of a concern, since HPV infection itself may contribute to skin cancer risk in that population.
Other conditions that mimic warts include seborrheic keratoses, which are benign growths that look waxy or “stuck on” and are extremely common after middle age. Molluscum contagiosum, caused by an entirely different virus, produces small, smooth, dome-shaped bumps with a dimpled center, often in children. Actinic keratoses, rough patches caused by sun damage, can feel like warts but are precancerous. If you’re treating what you think is a wart and it isn’t improving after several weeks of over-the-counter salicylic acid or home freezing kits, the lesion may not actually be a wart, and having a professional take a closer look is a reasonable next step.