Disease Description (Causes and Symptoms)
- Definition: A corn is a localized thickening of the skin in a cone-shaped form, with its base facing the skin surface and its tip (core) directed inward. A callus is a relatively broad and flat area of thickened skin.
- Causes·pathophysiology: Chronic localized pressure and friction (twisting, tight shoes, localized bony prominences, etc.) cause the stratum corneum to thicken as a defensive response of the skin. When pressure is concentrated in a narrow area, a central core forms and presses on the nerves at the base, causing pain. Soft corns develop in the moist environment between the toes.
- Main symptoms: A localized, hard, thickened-skin lesion; a penetrating central core (sharp, deep-seated pain); and sharp pain or dull discomfort when walking or under pressure. Soft corns are white and moist and painful when irritated.
Treatment Methods
- Conservative treatment (recommended as the first-line approach)
- Remove or reduce the cause: Wear comfortable shoes, shoes with a wide toe box, and insoles that fit the shape of the foot (orthotics); use pads or silicone protectors to distribute pressure.
- Mechanical management: Safe removal of thickened skin (paring, debridement) performed by a medical professional (dermatologist, foot doctor, or podiatrist).
- Topical medications: Topical application of salicylic acid (such as a 40% patch) or other keratolytics (follow the directions for use). Chemical cauterization with dichloroacetic acid, etc., may be used cautiously.
- Soft corns: Keep the area dry and separated (using cotton material or pads) and perform simple excision if necessary.
- Procedural·surgical treatment
- In cases of repeated recurrence or when a bony prominence (such as hallux valgus or a plantar prominence of the metatarsal) is the cause: Consider orthopedic surgery to correct the cause, such as removing the protruding bone, along with removal of the lesion’s core.
- If pain is severe or conservative treatment fails: Local surgery (core removal and excision of the surrounding thickened skin).
- Precautions and self-care
- Self-incision or shaving (especially using sharp tools) is not recommended because of the risk of wounds and infection (which can be serious in people with diabetes or peripheral vascular disease).
- People with diabetes or peripheral neuropathy must follow the instructions of a specialist (foot doctor/dermatologist).
- Recurrence is common if the underlying causes (shoes, body weight, foot shape, etc.) remain even after treatment.
- Complications
- Local infection (rarely progressing to bacteremia), ulcer formation, and, in severe cases, osteomyelitis (mainly in people with diabetes) may occur.
- Prognosis
- Most cases improve and are relieved when the cause is removed. Recurrence is common if the cause persists.
Checklist Before an Outpatient Visit (Items to Bring·Records·Example Questions)
- Items to prepare/bring
- A list of medications currently being taken (especially anticoagulants, antiplatelet agents, immunosuppressants, etc.)
- Previous relevant test results or medical certificates (if available)
- Recent photographs (to document changes in the lesion’s size, shape, and color)
- Photographs of the shoes (the shape of the shoes causing the problem) or the shoes usually worn
- Information to organize before the appointment
- When the lesion appeared and how it has progressed (when it started, whether it has gradually enlarged, changes in pain, etc.)
- The nature of the pain (sharp or dull) and triggers (walking, wearing shoes, etc.)
- Previous treatments and self-care (use of salicylic acid, attempts to remove the thickened skin, etc.) and their effects
- Whether any underlying conditions are present (diabetes, peripheral vascular disease, neuropathy, rheumatoid disease, etc.)
- Examples of questions the doctor may ask (to prepare in advance)
- When the symptoms started and how they have progressed
- Factors that worsen or improve the symptoms
- Previous treatment history and its effects
Examples of General Questions to Ask the Doctor
- Is this lesion definitely a corn (or callus)? What tests are needed for differential diagnosis?
- How should the medication being considered (e.g., salicylic acid) be used, and what are its side effects?
- Is it safe to shave off the thickened skin at home? Is there a safe way to do this?
- How likely is recurrence, and what should I do to reduce the risk of recurrence?
- What special precautions should I take if I have diabetes or a circulatory disorder?
Examples of Condition-Specific Questions
- What tests are needed to determine whether this corn is caused by the structure of my foot (a bony prominence or foot alignment problem)? (e.g., foot X-ray, orthopedic consultation)
- If it repeatedly recurs, would you recommend surgery (such as removing the bony prominence)? What are the expected benefits and risks of surgery?