Nail psoriasis: pitting, lifting nails and treatment options in the UK

Psoriasis is a common skin condition in which skin cells are produced faster than usual, forming scaly patches. The NHS says it can also appear on the fingernails, where the surface of the nail can have dents and pits. Nail psoriasis is simply psoriasis affecting the nail unit, which includes the nail plate, the nail bed beneath it and the tissue at its base.

PCDS explains that nail dystrophy mainly occurs in people who also have psoriasis of the skin. Fewer than 5 in 100 people have psoriasis that affects only the nails, which is one reason why a person who has never had skin psoriasis may be given a different diagnosis first.

Psoriasis is not contagious, as the NHS and NHS inform both stress, so nail psoriasis cannot be passed on to other people.

PCDS lists the typical clinical findings. Pitting consists of small dents in the nail surface. Onycholysis is a yellow or white discolouration where the end of the nail plate has separated from the nail bed. Subungual hyperkeratosis is thickening of the tissue under the nail. The oil drop or salmon patch is a translucent yellow-red discolouration in the nail bed that resembles a drop of oil under the nail plate.

NHS inform adds that nails may become discoloured, grow abnormally, separate from the nail bed and, in severe cases, crumble. The NHS image description of an affected fingernail refers to several small pits and dents as well as thicker, whiter areas near the tip.

• Pitting: small dents on the nail surface.

• Onycholysis: the nail lifting from the nail bed, leaving a yellow or white area.

• Subungual hyperkeratosis: thickening under the nail.

• Oil drop (salmon patch) discolouration in the nail bed.

• Crumbling or abnormal growth in severe cases.

The NHS says some people with psoriasis can develop psoriatic arthritis as they get older, an inflammatory condition that affects the joints. It advises seeing a GP if you have psoriasis and also have pain, stiffness and swelling in your joints that keeps coming back.

PCDS notes a strong link between nail disease and psoriatic arthritis, and recommends that all patients with psoriasis are assessed for psoriatic arthropathy at diagnosis and then annually, because early intervention can reduce joint damage. NICE guidance says to offer annual assessment for psoriatic arthritis to people with any type of psoriasis, particularly within the first 10 years of onset. For someone whose nails have changed, it is therefore worth mentioning any joint pain or morning stiffness, particularly in the fingers and toes.

The diagnosis is usually made from the appearance of the nails together with any psoriasis on the skin, scalp or elsewhere. PCDS advises examination of the skin and scalp as well as the nails.

The important alternative is a fungal nail infection. PCDS says samples must be sent for mycology if there is any diagnostic uncertainty, that it is important to include not only nail clippings but also scrapings from the undersurface of the nail plate, otherwise many cases of tinea will be missed, and that psoriasis and tinea of the nails can co-exist. NICE says that in specialist settings the Nail Psoriasis Severity Index can be used to assess nail disease where there is a major functional or cosmetic impact, or before and after treatment aimed at the nails.

PCDS is frank that treatment is difficult and results are often disappointing, and that people should be encouraged to keep their nails short. For troublesome cases, if the end of the nail is involved it advises cutting the nail back as far as possible and applying a potent topical steroid, possibly combined with a vitamin D analogue, once a day for a trial period of three months.

For more substantial involvement, including the base of the nail, PCDS suggests considering referral to dermatology for a trial of triamcinolone injections. Systemic agents such as methotrexate are occasionally used but benefit is not guaranteed, and the balance of risk and benefit means they are not often justified unless the nail changes are severe or the person also has moderate to severe psoriasis of the skin.

NHS inform lists the wider systemic and biological treatments used when psoriasis is severe: methotrexate, ciclosporin and acitretin as tablets or capsules, and etanercept, adalimumab, infliximab and ustekinumab as injections.

Nail psoriasis can be uncomfortable and affect function, for example picking up small objects or typing, as well as appearance. The NHS notes that living with psoriasis can be difficult and that if it affects mental health a referral to a mental health specialist may be offered.

The NHS also recommends general measures for psoriasis: trying to avoid known triggers, eating a healthy balanced diet, taking regular exercise, reducing stress, not drinking too much alcohol and trying to stop smoking. NHS inform adds that an injury to the skin, such as a cut, insect bite or sunburn, is a common trigger.

On the NHS, a GP can recognise nail psoriasis, take nail samples to exclude fungus and prescribe topical treatment, and will refer to dermatology for injections, phototherapy or systemic treatment. Anyone with joint symptoms may be referred to a rheumatologist.

Private dermatology is an option for a quicker opinion or nail injections. Whichever route is taken, the advice about confirming the diagnosis and checking the joints applies equally.