What is psoriasis?
Psoriasis is a chronic inflammatory skin disease in which there are clearly defined, red, scaly plaques (thickened skin). There are various subtypes of psoriasis.
How does psoriasis affect the palms and soles?
Psoriasis may be localised to the palms and soles or part of generalised chronic plaque psoriasis. Two common patterns are observed:
- Well-circumscribed, red, scaly, plaques similar to psoriasis elsewhere
- Patchy or generalised thickening and scaling of the entire surface of palms and/or soles without redness (an acquired keratoderma)
Palmoplantar pustulosis and the rare acrodermatitis continua of Hallopeau (acral pustulosis), in which yellow-brown pustules occur, are no longer classified as psoriasis. However, the conditions are associated. About 10–25% of people with palmoplantar pustulosis also have chronic plaque psoriasis.
What causes palmoplantar psoriasis?
The tendency to psoriasis is inherited, but what causes it to localise on the palms and soles is unknown. It may be triggered by an injury to the skin, an infection, or another skin condition such as hand dermatitis. It may first occur during a period of psychosocial stress. Certain medications, particularly lithium, may be associated with the onset of flares of psoriasis.
What are the clinical features of palmoplantar psoriasis?
Palms and soles affected by psoriasis tend to be partially or completely red, dry and thickened, often with deep painful cracks (fissures). The skin changes tend to have a sharp border and are often symmetrical, ie similar distribution on both palms and/or both soles. At times, palmar psoriasis can be quite hard to differentiate from hand dermatitis and other forms of acquired keratoderma. Plantar psoriasis may sometimes be similar in appearance to tinea pedis. There may be signs of psoriasis elsewhere.
Palmoplantar psoriasis tends to be a chronic condition, ie, it is very persistent.
Compared to chronic plaque psoriasis on other sites, palmoplantar psoriasis is more commonly associated with:
How is the diagnosis of palmoplantar psoriasis made?
Palmoplantar psoriasis is diagnosed by its clinical appearance, supported by finding chronic plaque psoriasis in other sites. Mycology of skin scrapings may be performed to exclude fungal infection. Skin biopsy is rarely needed.
The differential diagnosis of palmoplantar psoriasis includes:
What is the treatment for palmoplantar psoriasis?
Improvement in general health can lead to an improvement in palmoplantar psoriasis.
- Weight loss, if overweight
- Regular exercise
- Stress management
- Minimum alcohol
- Smoking cessation
- Investigation and management of associated health conditions
Mild psoriasis of the palms and soles may be treated with topical treatments:
- Emollients: thick, greasy barrier creams applied thinly and frequently to moisturise the dry, scaly skin and help prevent painful cracking.
- Keratolytic agents such as urea or salicylic acid to thin down the thick scaling skin. Several companies market effective heel balms containing these and other agents.
- Coal tar: to improve the scale and inflammation. Because of the mess, coal tar is often applied at night under cotton gloves or socks.
- Topical steroids: ultrapotent ointment applied initially daily for two to four weeks, if necessary under occlusion, to reduce inflammation, itch and scaling. Maintenance use should be confined to 2 days each week (weekend pulses) to avoid thinning the skin and causing psoriasis to become more extensive.
Calcipotriol ointment is not very successful for palmoplantar psoriasis. It may also cause an irritant contact dermatitis on the face if a treated area inadvertently touches it. Dithranol is too messy and irritating for routine use on hands and feet.
More severe palmoplantar psoriasis usually requires phototherapy or systemic agents, most often:
Biologics (targeted therapies) are also sometimes prescribed for severe palmoplantar psoriasis. However, it should be noted that TNF-alpha inhibitors such as infliximab and adalimumab may trigger palmoplantar pustulosis.