March 6, 2025
Figuratively speaking, it’s a good thing to have “thick skin,” right? But if you have palmoplantar keratoderma, it’s a different story. This condition, sometimes shortened to PPK, refers to a group of foot skin disorders characterized by thick, rough, and yellowed skin on the hand palms and feet soles. These conditions can be either inherited or acquired. In today’s article, we’ll explore the symptoms, causes, and, most importantly, the treatment options available. This type of skin thickening may warrant a trip to a foot clinic and the expertise of a foot care professional, such as a Chiropodist or Podiatrist. However, successful treatment may depend on the underlying cause of the skin thickening.
What is Palmoplantar Keratoderma?
This condition combines two scientific terms: palmoplantar, which specifically refers to the skin on the soles of the feet and the palms of the hands, and keratoderma, a term for epidermis (skin) thickening. In less common cases, transgradient keratoderma can affect the top of the hands and feet. The feet are usually more severely affected than the hands.
Palmoplantar keratoderma (PPK) causes thickened skin on the palms and soles due to an overproduction of keratin, the protein that forms the outer layer of the skin. Normally, keratin helps protect the skin from friction, pressure, and environmental damage. However, in PPK, something disrupts the balance of keratin production and shedding, leading to excessive buildup.
This happens because of genetic mutations or external factors that affect how skin cells grow and mature. Inherited forms of PPK often involve mutations in genes that control keratin formation or the connections between skin cells. These mutations make the skin cells more resistant to breaking down, so they pile up instead of naturally shedding.
Since the palms and soles experience the most pressure and friction in daily life, they are especially prone to this excessive keratin buildup. Over time, the thickened skin can cause pain or become hard and cracked, depending on the severity of the condition. Some types can also cause blisters to form.
Types of Palmoplantar Keratoderma and Associated Symptoms
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Genetic (hereditary) keratoderma is usually divided into three main categories: diffuse, affecting the entire hand palm and foot sole; focal, where thickening is limited to pressure points; and punctate, which appears as small, hard lesions. Some genetic PPKs - particularly diffuse - are syndromic, meaning they are associated with other health conditions and additional symptoms, ranging from hearing loss to nail abnormalities to internal organ damage.
Acquired PPK, on the other hand, is always syndromic and develops later in life due to external factors such as infections, inflammatory diseases, or underlying systemic conditions like internal malignancies. Acquired forms may be easier to treat since you and your healthcare team can address the underlying cause. Acquired PPK is also more common than genetic, since there are more causes and risk factors associated with it.
Most types of PPK cause varying degrees of thick skin, potential foot odor (as a result of sweat combined with thick skin) and yellow/discoloured skin.
Genetic PPK Types and Symptoms
Diffuse PPK
This form presents with even thickened skin on the palms and soles, often with a red border at the edges. Symptoms typically appear in early childhood and may include excessive sweating (hyperhidrosis). The thickening is usually confined to the palms and soles, without extending to the tops of the hands or feet.
Focal PPK
This type is characterized by linear (striate) thickened areas on the palms and soles, often following the lines of skin tension. It is typically caused by mutations in genes encoding desmosomal proteins, which are crucial for cell adhesion. A specific type of focal PPK called Pachyonychia Congenita is a rare genetic disorder that can also cause thick toenails.
Punctate PPK
This form is characterized by multiple small, hard, corn-like lesions scattered on the palms and soles. It is associated with mutations in genes that play a role in skin cell function.
Acquired PPK Types and Symptoms
PPK from Infections (syphilis, etc)
Rough, scaly and yellow thickening on the palms and soles.
May come with a rash or other symptoms affecting the whole body.
Clears up when the infection is treated.
PPK from Inflammatory Skin Conditions (psoriasis, eczema)
Thickened, inflamed skin with redness and scaling.
Can extend beyond just the palms and soles.
Often improves with medicated creams or treatments that calm the immune system.
PPK Linked to Other Health Conditions (cancer, hormone disorders)
Yellow thickening of the palms and soles that appears suddenly in adulthood.
Can sometimes signal an underlying health issue, like cancer.
Needs further medical evaluation to check for possible internal diseases.
What is the Difference Between Palmoplantar Keratoderma and Calluses?
PPK is not the only cause of skin thickening on the feet and hands. In fact, it is more rare than another common culprit: calluses. But how do you know which condition you have?
Calluses are localized areas of thickened skin that develop as a protective response to repeated friction or pressure. Commonly found on individuals who are physically active or spend long hours wearing ill-fitting shoes, they are much less severe than PPK.
PPK tends to be thicker and more noticeable, alarming and unsightly than calluses, often covering a larger, symmetrical area on the palms and soles. It can appear hard and more yellow, or red and flaky. In some PPK cases, you may observe a red band at the edges of the thickened skin. Calluses can have a more mild appearance (but not always; they can sometimes be thick and painful!), with some people not even realizing they have them.
Does that mean that PPK is the same as having excessive calluses? Not exactly. Calluses are only caused by friction and pressure----whereas PPK always has a driving force behind it, whether it's a genetic mutation or the result of an illness.
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Palmoplantar Keratoderma Treatment: Can a Chiropodist or Podiatrist Help?
While there is no outright cure for certain forms of PPK, Chiropodists and Podiatrists can help manage symptoms, reduce discomfort, and improve mobility. This typically involves regular debridement (carefully removing excess skin), possibly prescribing medicinal products, and offering footwear advice to minimize friction and pressure. The latter may also include prescribing custom orthotics to properly distribute pressure on the bottom of the feet, especially if the thickened skin is impacting daily life. Scheduling an initial assessment is a good start!
Naturally, since PPK can be linked to an underlying condition, more comprehensive care may be needed. A Chiropodist or Podiatrist might become a part of a broader team of healthcare professionals that can help you, including a dermatologist, your family doctor or other specialists trained to tackle the root cause. You may need advanced treatments such as topical retinoids, corticosteroids, or even laser therapy in some cases.
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