Pitted keratolysis, a bacterial skin infection that produces clusters of small crater-like depressions on the soles of the feet, is the condition people most often encounter when they notice small holes in their skin. But it is far from the only possibility. Several unrelated diseases, from rare autoimmune disorders to parasitic infestations, can create pits, perforations, or hole-like lesions in the skin, and the cause matters enormously for treatment.
Pitted Keratolysis Is the Most Common Culprit
If you have noticed small, punched-out pits on the soles of your feet, especially along the heel or the ball of the foot, pitted keratolysis is the most likely explanation. The pits are typically shallow, round or slightly irregular, and clustered in groups. They often come with a strikingly unpleasant smell. The condition is not dangerous, but it can be persistent and uncomfortable.
Pitted keratolysis is caused by bacteria that thrive in warm, moist conditions. Several species have been implicated, but the best studied is Kytococcus sedentarius, which produces two enzymes capable of independently breaking down the tough keratin protein in the outer layer of skin. Both enzymes are serine proteases with the ability to degrade natural, insoluble human callus tissue, effectively dissolving small craters into the thickened skin of the soles.1PubMed. Kytococcus sedentarius, the organism associated with pitted keratolysis, produces two keratin-degrading enzymes Other bacterial species, including Corynebacterium and Dermatophilus congolensis, can cause the same presentation.
The conditions that allow these bacteria to proliferate are predictable: prolonged wearing of occlusive footwear, excessive sweating, and an elevated skin surface pH. When thick callus develops on weight-bearing areas of the foot, it provides a ready substrate for the bacteria’s protein-digesting enzymes. Once the bacteria colonize that callus layer, they produce proteinases that carve out the characteristic pits and generate the sulfur compounds responsible for the foul odor.2PubMed Central. Plantar pitted keratolysis: a study from non-risk groups
People who work in occupations requiring heavy boots for long hours, athletes, and anyone in a hot, humid climate are at higher risk. Military personnel have historically had high rates. But it can appear in anyone whose feet stay damp and enclosed for extended periods.
How Pitted Keratolysis Is Treated
The good news is that treatment is straightforward. Topical antibiotics, particularly erythromycin gel or clindamycin solution, clear the infection reliably. In one clinical series, patients treated with erythromycin 3% gel applied twice daily saw both the clinical lesions and their excessive sweating resolve within ten days.3PubMed. Pitted keratolysis, erythromycin, and hyperhidrosis The pits themselves fill in over the following weeks as normal skin regeneration takes over.
Preventing recurrence is just as important as treating the active infection. Keeping feet dry, changing socks during the day, choosing breathable footwear when possible, and applying antiperspirant to the soles can all reduce the chance the bacteria will come back. If you have thick calluses, periodic removal with a pumice stone or professional pedicure reduces the substrate the bacteria feed on.
Perforating Dermatoses
A more unusual group of skin conditions, collectively called the perforating dermatoses, creates holes in skin through a dramatically different mechanism. Instead of bacteria eating away at the surface, the body itself pushes internal material outward through the skin, creating small channels and pits. The substances being expelled vary by the specific disease but include collagen fibers and elastic tissue.
Acquired reactive perforating collagenosis is a rare condition in which altered collagen fibers from the deeper layer of skin are eliminated upward through the surface layer. It typically appears as dome-shaped bumps with a central crater or plug, and under a microscope, you can see full-thickness defects in the epidermis where bundles of thickened collagen have been pushed through.4PubMed Central. Successful Nemolizumab Treatment of Refractory Acquired Reactive Perforating Collagenosis in a Diabetic Patient This condition is strongly associated with chronic kidney disease and diabetes. It shows up frequently in people on dialysis, where it may be triggered by the metabolic disturbances and intense itching that accompany kidney failure.5PubMed. Two Cases of Acquired Reactive Perforating Collagenosis in Hemodialysis Patients
Elastosis perforans serpiginosa is another perforating condition, but here the material being expelled is elastic fiber rather than collagen. It presents as small, firm bumps arranged in curved or ring-shaped patterns, and biopsy reveals a narrow channel through the skin filled with degenerated elastic tissue.6PubMed Central. Elastosis perforans serpiginosa It can occur on its own but is also a known side effect of the drug D-penicillamine, used to treat Wilson’s disease and some forms of arthritis. In drug-induced cases, the medication appears to cause abnormal elastic fibers to form, which the body then attempts to eject through the skin surface.7PubMed Central. Elastosis Perforans Serpiginosa: a D-penicillamine induced dermatoses in a patient with Wilson’s disease
If you develop small pitted or plugged lesions on your arms, legs, or trunk, and you have diabetes, kidney disease, or are taking D-penicillamine, a perforating dermatosis should be on the differential. These conditions are rare enough that many general practitioners have not encountered them, so a dermatologist may be needed for an accurate diagnosis.
Parasites That Create Holes in Skin
In tropical and subtropical regions, two parasitic infestations can create skin lesions that look distinctly hole-like. Both involve a living organism literally burrowing into or embedding within the skin.
Tungiasis is caused by the sand flea Tunga penetrans, which burrows into the epidermis and swells dramatically as it feeds. The result is a painful nodule with a visible central black dot, which is the rear end of the flea remaining open to the outside air. The surrounding skin often becomes red and inflamed, and secondary bacterial infections are common complications.8PubMed Central. Tungiasis–a neglected disease with many challenges for global public health Tungiasis primarily affects the feet and toes, since the flea lives in sandy soil and attacks from the ground up. It remains widespread in parts of sub-Saharan Africa, Central America, and South America, and travelers who walk barefoot in endemic areas occasionally bring it home.
Furuncular myiasis is caused by fly larvae, most commonly the botfly (Dermatobia hominis) in the Americas. The developing larva grows beneath the skin inside a firm, boil-like nodule that has a central pore, through which the larva breathes.9PubMed Central. Cutaneous furuncular myiasis: Human infestation by the botfly People sometimes notice movement inside the lesion or feel a prickling sensation. The characteristic central opening, through which a small breathing tube may be visible, distinguishes myiasis from a typical boil or cyst. Treatment involves extracting the larva, often by covering the pore with an occlusive substance to force the larva to surface for air.
Neither tungiasis nor myiasis is something you would develop without having been in an area where these parasites live. If you have never traveled to the tropics or subtropics, these conditions are extremely unlikely explanations for holes in your skin.
Scleroderma and Digital Pitting Scars
Small, pit-like depressions on the fingertips can be a sign of systemic sclerosis, commonly known as scleroderma. This autoimmune disease causes progressive thickening and hardening of the skin and connective tissue, and one of its subtler manifestations is the appearance of tiny, pinhole-sized concave scars on the fingers. In one study of 87 scleroderma patients followed over time, these pitting scars were found in about 39% of cases. They appeared not just on the fingertips but also on the sides of the fingers, particularly along the thumb and index finger, often arranged in a linear pattern.10PubMed. Pitting scars in progressive systemic sclerosis
The scars are thought to form from a combination of reduced blood flow to the small vessels of the fingers (a hallmark of scleroderma called Raynaud’s phenomenon), mechanical trauma to skin that has lost its normal elasticity, and possibly cold exposure. Under a microscope, the pits show a plug of thickened keratin, hardened collagen fibers, and mild inflammation around small blood vessels.10PubMed. Pitting scars in progressive systemic sclerosis
If you have Raynaud’s phenomenon along with unexplained pitting of the fingertips, color changes in the skin of the hands, or tightness of the skin on the fingers, it is worth mentioning to a doctor. Digital pitting scars can be an early visible clue to scleroderma before more obvious features develop.
Infections That Produce Ulcerated Holes
Some infections create larger, more dramatic openings in the skin that go beyond simple pitting. These lesions tend to start as bumps or sores and progress to open, crater-like ulcers if untreated.
Cutaneous leishmaniasis is a protozoal infection spread by sandflies in parts of Central and South America, the Middle East, and Central Asia. It typically presents as a slowly enlarging ulcer with raised borders, often on exposed skin like the face, arms, or legs. The ulcer has a punched-out appearance and is sometimes mistaken for a non-healing wound or skin cancer. Because it can look like many other conditions, diagnosis outside endemic regions often requires specialized laboratory testing.11PubMed Central. Cutaneous Leishmaniasis Requiring Polymerase Chain Reaction (PCR)-Based Diagnosis
Ecthyma gangrenosum is a different beast entirely. This is a necrotic skin lesion associated with severe bloodstream infection, most commonly caused by the bacterium Pseudomonas aeruginosa. It begins as a painless red spot that rapidly darkens and breaks down into a black, crater-like wound with surrounding inflammation. It is predominantly seen in people with weakened immune systems, although rare cases in previously healthy individuals have been reported.12PubMed Central. Ecthyma gangrenosum, a skin manifestation of Pseudomonas aeruginosa sepsis in a previously healthy child: A case report Ecthyma gangrenosum is a medical emergency because it signals active sepsis.
Small-vessel vasculitis can also produce skin holes, though its mechanism is quite different. When inflammation destroys the walls of tiny blood vessels in the skin, the tissue they supply dies. This can result in small ulcers, purpura (purple spots), and necrotic patches that may look like punched-out holes.13PubMed Central. A rheumatology perspective on cutaneous vasculitis: assessment and investigation for the non-rheumatologist Vasculitis can be a standalone condition or a complication of autoimmune diseases, infections, or drug reactions.
Ice Pick Acne Scars
One of the most common reasons people search for “small holes in skin” is actually not an active disease at all but rather scars left behind by severe acne. Ice pick scars are narrow, deep, V-shaped pits that extend down into the deeper layers of the skin. They are the most visually distinctive type of acne scar and the hardest to treat, because their depth and narrow shape make them resistant to standard resurfacing procedures.
These scars form when a deep inflammatory acne lesion destroys a column of tissue as it heals. The skin closes over the top but collapses inward, leaving a tiny but noticeable hole. They are most common on the cheeks and temples and tend to be more prominent in people who experienced cystic or nodular acne.
The treatment that has shown the most consistent results for ice pick scars is a procedure called CROSS, which stands for chemical reconstruction of skin scars. It involves applying a high concentration of trichloroacetic acid directly into each individual scar, triggering a controlled wound-healing response that stimulates new collagen growth from the bottom up. In studies evaluating this technique, the majority of patients achieved substantial improvement. One study found that more than 70% improvement was observed in eight out of ten patients evaluated.14PubMed Central. An Assessment of the Efficacy and Safety of CROSS Technique with 100% TCA in the Management of Ice Pick Acne Scars A separate study in patients with darker skin tones found excellent improvement in roughly three-quarters of patients after four sessions.15PubMed. Evaluation of CROSS technique with 100% TCA in the management of ice pick acne scars in darker skin types
Combining CROSS with other techniques like subcision, which releases scar tissue tethered beneath the surface, and microneedling can produce even better outcomes by addressing different layers of the skin simultaneously.16PubMed Central. A Combination Approach to Treating Acne Scars in All Skin Types: Carbolic Chemical Reconstruction of Skin Scars, Blunt Bi-level Cannula Subcision, and Microneedling-A Case Series These are office-based procedures performed by dermatologists, typically in a series of sessions spaced several weeks apart.
When to See a Doctor Versus When to Wait
The conditions described above range from cosmetic nuisances to medical emergencies, so the question of urgency depends heavily on context. Here are some practical guidelines:
- Smelly pits on the soles: Likely pitted keratolysis. You can try keeping your feet dry and applying an over-the-counter antibacterial wash for a week or two. If it does not clear up, see a doctor for a topical antibiotic prescription.
- Pitted scars on fingertips with cold sensitivity: Mention it to your doctor at your next visit. If your fingers turn white or blue in the cold, or if your skin feels unusually tight, bring it up sooner.
- Crater-shaped bumps with central plugs on your arms or legs: See a dermatologist, especially if you have diabetes or kidney disease. These perforating conditions need a biopsy for diagnosis.
- A rapidly darkening, necrotic wound: Go to the emergency room. Ecthyma gangrenosum and similar necrotic infections can indicate sepsis.
- A non-healing ulcer after tropical travel: See a doctor and mention your travel history. Leishmaniasis and tungiasis need specific treatment that standard wound care will not provide.
- Old acne pits bothering you cosmetically: Consult a dermatologist who specializes in scar revision when you are ready. There is no urgency, but the scars will not improve on their own.
A general rule: if the holes are new, spreading, painful, or accompanied by fever, redness tracking away from the site, or general malaise, that warrants prompt medical attention. Stable, long-standing pits that are not changing are much less concerning and can be addressed at a convenient time.
Trypophobia and Why Holes in Skin Feel So Disturbing
Beyond the medical questions, there is a psychological dimension worth addressing. Many people who search for information about holes in skin are not looking at their own body at all. They stumbled across an image online, felt an immediate wave of revulsion, and want to understand what they saw and why it bothered them so intensely.
That reaction has a name: trypophobia, an intense and disproportionate aversion to clusters of small holes, bumps, or repetitive patterns. It is often accompanied by physical symptoms like skin crawling, itching, nausea, or goosebumps.17PubMed Central. Trypophobia: What Do We Know So Far? A Case Report and Comprehensive Review of the Literature The reaction is particularly strong when the pattern involves skin, as in images of pitted keratolysis, lotus seed pods digitally altered to look like human skin, or real parasitic infestations.
Research suggests that the disgust response in trypophobia is rooted in disease avoidance. In studies measuring emotional responses to cluster images, the dominant feeling reported was disgust rather than fear, and many participants described accompanying sensations of itching or crawling on their own skin. These findings support the idea that trypophobia represents an overactive version of a system that evolved to help us recognize and avoid skin-transmitted parasites and pathogens.18PubMed. Disgusting clusters: trypophobia as an overgeneralised disease avoidance response
A 2024 study added nuance to this picture. Researchers found that while everyone finds images of actual skin disease uncomfortable to look at, only people who score high on trypophobia measures show the same level of discomfort toward abstract cluster patterns that do not depict disease. In other words, trypophobia appears to involve a misfiring of the visual and emotional systems that normally help us recognize diseased skin, applying that alarm signal to harmless patterns like honeycombs, sponges, or aerated chocolate.19PubMed Central. Trypophobia, skin disease, and the visual discomfort of natural textures
Trypophobia is not currently recognized as a formal diagnosis in major psychiatric classification systems, though it can cause genuine distress. If images of clustered holes trigger anxiety or intrusive thoughts that interfere with your daily life, that is worth mentioning to a mental health provider. The reaction itself is remarkably common, though, and having a strong disgust response to holes in skin does not mean something is wrong with you. Evolutionarily speaking, it might mean your threat detection is simply tuned a little high.