Corns, Callous and Blisters: The What, Where, When and Why of Common Dermal Lesions

shutterstock_314339363.jpgSkin lesions as a result of friction are a common nuisance for a large percentage of people. Blisters, callus and corns are three of these lesions which present on a regular occasion to podiatry clinics. The questions posed around the pathologies are based on what the actual presentation is and how it came to be. In this article we look to answer those questions in a quick-fire way.


What: Blisters – are small pockets of fluid under the upper layers of the skin as a result of high friction and heat.

Where: Blisters can occur anywhere. However, common places for blister presentations is at the medial and plantar aspects of the foot.

When: Blisters generally occur as a result of short term repetitive friction or high pressure across a specific spot or region.

Why: Friction associated with blisters commonly occurs as a result of an introduction to a new environment. This may include but is not limited to; socks, shoes, insoles/ orthotics or playing surface.


What: Callus – Callus is a build-up of skin as a result medium to long term friction. Its clinical name is hyperkeratosis or HK and is thus named due to the abnormally high quantity of keratin it establishes as a lesion.

Where: Callus typically forms on both the dorsal and plantar aspect of the foot. It can be associated with bony deformities or biomechanical issues.

When: Callus builds as the skin tries to protect itself from increased pressures at a specific spot or region.

Why: Friction over a medium to longer period or duration can cause the development of callus. High pressure areas created by deformities, ill or inappropriate fitting shoes and individual biomechanics are the primary cause. Much of the time these areas can be addressed and improved.


What: Corns – are a pathological build-up of tissue which may lead to pain normally as a result of unattended Callus development.

Where: Corns have the potential to form anywhere friction occurs. Typically, they occur on the plantar aspect of the metatarsal phalangeal joints (MTPJs) and dorsal aspect of the interphalangeal joints (IPJs).

When: Corn will occur when callus builds at a specific point in a cone shape lesion which causes pain during weight bearing.

Why: Corns are more likely to result from specific pressure areas such as bony deformities and shoes which may increase the area of pressure.

In conclusion, skin lesions as a result of friction can be a nuisance but worse than that, they can be painful. In some circumstances all 3 can lead into each other and create a cycle of skin build-up which will continue to cause issues more than a couple of times.

Until Next Time

Jackson McCosker
Director/ Chief Editor

Categories Uncategorized

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