Calluses & Corns

Definition

• Calluses (Tyloma): A diffuse thickening of the stratum corneum caused by repeated friction or pressure on the skin. Typically painless but can become tender if there is ongoing irritation.

• Corns (Clavus, Heloma): A more localised form of hyperkeratosis that presents with a hardened, central core. They commonly occur over bony prominences (e.g. the dorsal aspect of toes) and are often painful.

Aetiology & Causes

• Chronic friction or pressure due to:

  • Ill-fitting shoes (narrow toe box, high heels, shoes too small or too large)

  • Bony prominences (hammer toes, bunions, foot deformities)

  • Abnormal gait or biomechanics (uneven weight distribution)

Pathophysiology

• Calluses: The skin thickens in response to repeated pressure or friction as a protective mechanism. The thickening tends to be more diffuse.

• Corns: Persistent or focused pressure over a bony prominence leads to a concentrated hyperkeratotic plug, or “core,” which can impinge on deeper structures and cause pain.

Symptoms

• Calluses:

  • Thick, rough, yellowish skin patches.

  • Usually painless, although they can become sore if further irritated.

  • Common sites: plantar aspect of the foot (especially under metatarsal heads), palms (if related to occupational friction).

• Corns:

  • Hard, cone-shaped lesions that press into the deeper dermis, causing sharp or burning pain.

  • Often appear on the dorsal surface of toes or between toes if moisture is retained (soft corns).

  • May limit mobility and footwear choices due to discomfort.

Differential Diagnosis

• Plantar warts (verrucae caused by HPV):

  • May show punctate capillary thromboses (“black dots”) upon debridement.

  • Disruption of normal skin lines (whereas calluses/corns tend to preserve skin lines).

  • Often painful when pinched side-to-side rather than direct pressure.

• Other causes of foot pain:

  • Metatarsalgia (pain in the forefoot region).

  • Morton’s neuroma.

  • Fungal infections (tinea pedis) if there is scaling and itching.

Management

• Pharmacological Treatment:

  • Salicylic Acid 40% Plasters:

    • Debulking: Pare the lesion gently with a #15 scalpel blade (or an emery board/pumice stone at home) to reduce thickness.

    • Application:

      • Cut the plaster to the size of the lesion.

      • Apply for 48–72 hours, keeping the area dry.

      • Check the site regularly for irritation.

    • Follow-up: Carefully remove softened skin. Repeat if necessary until improvement.

• Non-Pharmacological Treatment:

  • Prevention:

    • Avoid ill-fitting or high-heeled shoes that concentrate pressure on a small area.

    • Consider orthotics or customised insoles for biomechanical issues, especially if recurrent lesions occur at the same spot.

  • Footwear advice: Wide toe box, adequate cushioning, and correct sizing help reduce pressure points.

  • Foot care:

    • Regularly soak feet in warm water and use a pumice stone or foot file to keep calluses from building up excessively.

    • Moisturise feet to prevent drying and fissuring of calluses.

  • Follow-up:

    • If no resolution or improvement in 2 weeks, re-evaluate diagnosis and consider referral to a podiatrist.

    • Use caution with salicylic acid in patients with peripheral neuropathy or peripheral vascular disease (risk of unnoticed injury or ulceration).

Notes

• Comorbidities: In diabetic or immunocompromised patients, careful foot inspection and podiatry referral might be warranted to avoid complications such as foot ulcers.

• Painful or persistent corns: May need ongoing paring or removal by a trained professional (e.g. podiatrist).

• Surgery: Rarely indicated unless there is an underlying severe foot deformity (e.g. bunions, claw toes) that repeatedly causes corns/calluses.