A hole or pit in a callus usually means you’re dealing with something more than ordinary thickened skin. The most common explanation is a corn, which is a small, concentrated area of hard skin with a dense central core that can look like a hole or indentation when viewed from above. But several other conditions can create a similar appearance, and telling them apart matters because the treatments are different.
Corns: The Most Likely Cause
A corn is essentially a callus with a focused center. While calluses spread across a wider area of skin and feel rough or yellowish, corns are smaller, more defined, and have a hard nucleus that presses inward. That central core is what creates the “hole” appearance. When you look closely at a corn, you’ll see a translucent or slightly darker circle in the middle of the thickened skin, almost like a plug has been pushed into it.
Corns form because of repeated pressure or friction on one specific spot. On the bottom of the foot, they tend to develop under the ball of the foot or on the heel, directly beneath a bony prominence like a metatarsal head. These are sometimes called intractable plantar keratoses, and they can extend surprisingly deep, typically ranging from 0.5 to 1 cm across. They hurt most when you press straight down on them, which is why they’re painful with every step.
A related but less common variant is the seed corn. These look like tiny beads or millet seeds embedded in the skin of the sole. They can appear alone or in clusters, on both weight-bearing and non-weight-bearing areas. Unlike regular corns, seed corns aren’t usually surrounded by a ring of callus. Their cause isn’t fully understood, and they’re often associated with dry skin rather than pressure alone.
Plantar Warts Can Mimic a Callus Hole
Plantar warts are one of the most commonly confused look-alikes. Caused by human papillomavirus, they develop on all surfaces of the foot and can build up a thick layer of callused skin on top, making them look like a callus with something unusual at the center.
The key difference is what you see when you look closely. Warts contain small, clogged blood vessels that appear as black dots or tiny dark specks, sometimes described as looking like seeds. A corn’s center, by contrast, is a solid plug of keratin without those dark pinpoints. Another reliable clue: if you squeeze the lesion from side to side (rather than pressing straight down) and it hurts, that points more toward a wart. Corns tend to hurt most with direct downward pressure. Warts also disrupt the normal skin lines (the ridges you can see on healthy skin), while corns do not.
Pitted Keratolysis: A Bacterial Infection
If the “holes” in your callus are actually many small pits clustered together, pitted keratolysis is a strong possibility. This is a bacterial skin infection that breaks down the outermost layer of skin, creating tiny crater-like indentations. The affected area often appears as a lighter patch of skin dotted with small, shallow holes that can merge into larger lesions.
Pitted keratolysis thrives in warm, moist environments. It’s especially common in people who wear enclosed shoes for long hours, sweat heavily, or go long periods without changing socks. The bacteria produce enzymes that literally dissolve the outer skin cells, which is why the pitting develops. A noticeable odor is common with this condition, and the affected skin may feel slimy or soggy. Unlike a corn, pitted keratolysis doesn’t produce a single central hole. Instead, you’ll see a cluster of tiny pits across a broader area.
Signs of Infection or Ulceration
Sometimes a hole in a callus isn’t a structural feature of the callus itself. It’s a sign that the tissue underneath has broken down. If you notice redness, swelling, pain that’s getting worse, or any oozing or pus coming from the area, the callus may have become infected. Drainage that shows up on your socks when you take them off is another red flag.
This is particularly important for people with diabetes or poor circulation. Calluses on the feet can mask developing ulcers underneath. As an ulcer worsens, it can widen and deepen, sometimes reaching the bone. Warning signs include a ring of harder tissue surrounding a central wound, brown discoloration, drainage, and a strong odor. Because diabetes can reduce sensation in the feet, you might not feel pain even as the tissue breaks down. If you have diabetes and notice any change in a callus, including what looks like a hole or soft spot, getting it evaluated promptly is important.
How a Podiatrist Removes the Core
If you’re dealing with a corn or a deep callus with a central nucleus, a podiatrist can remove it through a process called debridement. This involves carefully paring away the thickened outer skin to expose and then remove the hard core. The procedure is done with a scalpel in the office, and most people feel immediate relief once the plug of compacted skin is out.
Removing the core addresses the symptom, but the corn will come back if the underlying pressure isn’t corrected. After debridement, a podiatrist may apply padding or strapping to redistribute pressure across the foot. They’ll also typically assess your footwear and the way you walk to identify what’s driving the repeated friction. Custom orthotics or simple shoe changes can make a significant difference. Surgery is reserved for severe or chronic cases where bone structure is the root problem.
Reducing Pressure at Home
For corns that aren’t infected or severely painful, pressure relief is the foundation of home care. A doughnut-shaped pad made from moleskin works well for smaller corns. Cut a circle of moleskin, then cut out the center so the pad surrounds the corn without pressing on it. This offloads pressure from the sensitive core while you walk.
For broader calluses on the ball of the foot, a metatarsal pad placed just behind the callused area can cushion the bone and reduce the friction that caused the buildup in the first place. These adhesive pads are inexpensive and available at most pharmacies.
Keeping the skin hydrated also helps. Urea-based foot creams at concentrations around 40% are effective at softening thick, compacted skin. Urea works as a keratolytic, meaning it breaks down the bonds between dead skin cells, making it easier to gently file away the buildup over time. Apply it to the callused area daily, but avoid putting it on broken or open skin. Pumice stones or foot files can gradually reduce callus thickness between applications, though you should never try to dig out a core yourself, as this risks infection and tissue damage.