Toe cancer most often appears as a dark streak under the toenail, a scaly bump on the skin, or a sore that won’t heal. The tricky part is that it frequently mimics common, harmless conditions like fungal infections, warts, and calluses, which is why cancers on the toes are often caught late. Knowing the specific visual signs for each type can help you spot something suspicious early.
The Most Common Types
Three main skin cancers affect the toes. Squamous cell carcinoma is the most common cancer on the skin of the feet overall. Melanoma is less common but far more dangerous. Basal cell carcinoma, the most frequent skin cancer elsewhere on the body, is relatively rare on the feet because toes get less sun exposure.
Each type looks different, and some have no pigment at all, making them easy to dismiss as something routine.
Dark Streaks Under the Nail
Subungual melanoma, the type that grows beneath a toenail, is the form most people picture when they think of toe cancer. It typically starts as a dark brown or black vertical streak running from the base of the nail toward the tip. Early on, the line is usually narrow, less than 3 millimeters wide. Over time it widens, darkens, and can eventually cover the entire nail surface.
The color is often uneven, with varying shades of brown and black rather than a uniform tone. As it progresses, the nail may split, crack, or lift away from the nail bed. One hallmark that doctors watch for is called Hutchinson’s sign: the dark pigment spills beyond the nail itself onto the surrounding skin of the cuticle or the sides of the toe. When that happens, it strongly suggests melanoma rather than a harmless pigmented streak.
Not every subungual melanoma is dark. Roughly one-third of melanomas on the feet lack brown or black pigment entirely, appearing pink or red instead. These colorless versions are particularly easy to miss because they don’t trigger the usual “dark spot” alarm.
How It Differs From Toenail Fungus
Toenail fungus causes thickening of the nail bed and white, yellow, or greenish discoloration, usually spread across the nail rather than concentrated in a single streak. Melanoma, by contrast, produces brown or black bands that increase in size over time, along with possible bleeding, nail separation, and darkening of the skin around the nail. A bruise under the nail (from stubbing your toe, for example) can also look like a dark spot, but it grows out with the nail over weeks and doesn’t widen or spread to the surrounding skin.
Scaly Bumps and Sores on the Skin
Squamous cell carcinoma on a toe often starts as a small, scaly bump or flat plaque that may look inflamed or reddened. It can crack and bleed repeatedly, and sometimes it develops into what looks and feels like a thick callus. The lesion is usually painless, though it may itch. What makes it deceptive is its resemblance to everyday foot problems: plantar warts, fungal patches, eczema, or a stubborn ulcer.
Basal cell carcinoma, when it does appear on a toe, tends to look like a pearly white bump or a patch that oozes, crusts over, and resembles a small open sore. On the lower legs and feet, it can also mimic a benign ulcer or a non-cancerous skin growth.
Melanoma on Toe Skin (Not Under the Nail)
Melanoma can also develop on the skin of the toes, on the top surface or between the toes, not just beneath the nail. This variant, called acral lentiginous melanoma, tends to start as a brown or black spot that grows slowly outward before thickening at the center. The borders are often irregular, and the color may be uneven. These lesions tend to be larger by the time they’re diagnosed, partly because people don’t check their feet as carefully as other parts of the body.
The colorless (amelanotic) version of this melanoma is especially dangerous. It can appear as a pinkish or yellowish thickened patch that looks almost identical to a wart or callus. One published case described a lesion that presented as a pinkish-yellow, scaly plaque closely resembling a common plantar wart. Because it lacked the dark pigment people associate with melanoma, the diagnosis was delayed. Any solitary, longstanding lesion on the foot that doesn’t respond to standard treatment deserves a closer look.
When a Sore Won’t Heal
A toe ulcer that refuses to heal despite proper wound care is another presentation of cancer, particularly in people with diabetes or chronic wounds. Warning signs that a non-healing ulcer may be malignant include:
- Everted or raised wound edges that roll outward rather than lying flat
- Excessive granulation tissue, where the wound looks overly “beefy” or lumpy
- Increasing size over three months or longer despite treatment
- Contact bleeding, where the wound bleeds easily when touched
- Foul-smelling discharge that may be mistaken for a simple bacterial infection
- A nodule or warty growth forming within the wound
These ulcers can be masked by infection, with the odor and drainage drawing attention away from the underlying cancer. Pain is not a reliable indicator either way, especially in people with nerve damage from diabetes.
Warning Signs Worth Checking For
A useful framework for evaluating a suspicious nail streak considers age (risk increases with age), whether the band is brown-black and wider than 3 millimeters, whether the pigment has changed or spread to the skin around the nail, and whether you have a personal or family history of melanoma. Any single factor isn’t necessarily alarming on its own, but a combination of several raises concern.
For lesions on the toe skin rather than under the nail, the standard asymmetry, border irregularity, color variation, and diameter guidelines still apply, with the caveat that amelanotic (colorless) melanomas break all those rules. The most reliable red flag for any spot on the toe is change: a mark that grows, darkens, bleeds, or refuses to heal over weeks.
How Toe Cancer Is Diagnosed
A visual exam alone can’t confirm toe cancer. Diagnosis requires a biopsy, where a small sample of tissue is removed and examined under a microscope. For lesions under the nail, doctors typically use a small cylindrical punch tool, about 3 millimeters wide, pressed through the nail plate down to the bone. This retrieves a core of tissue without requiring the entire nail to be removed first. For lesions on the skin of the toe, a standard skin biopsy works the same way it would anywhere else on the body.
Because toe cancers so closely resemble common benign conditions, any persistent, changing, or treatment-resistant lesion on the toe is worth having biopsied. Early detection is especially critical for melanoma, where outcomes depend heavily on catching the cancer before it grows deeper into the skin and spreads through the lymphatic system or bloodstream.