Nail lichen planus: nail thinning, ridging and why early review matters

The PCDS describes lichen planus (LP) as a fairly common, itchy, non-infectious rash that usually occurs in adults. The word lichen refers to small bumps on the skin and planus means flat, together referring to the characteristic flat-topped papules. It is thought to be an immunologically mediated disorder with a slight genetic susceptibility, and can affect any part of the body, most commonly the wrists, ankles and lower back, as well as the mouth and genital area.

It can also affect the nails, with or without skin changes, and in the scalp as follicular lichen planus (lichen planopilaris), which is dealt with separately.

The PCDS says nails are involved in 10% of cases of lichen planus, fingernails more than toenails, with initial involvement of two or three fingernails before the remaining digits. Thinning of the nail plate with longitudinal changes predominates. In its nail disorders guidance, it lists the changes below.

• Thinning of the nail plate.

• Longitudinal ridging, lines running along the length of the nail.

• In some cases roughness of the whole nail surface (trachyonychia), which can be associated with longitudinal ridging.

• In severe cases, permanent deformity or destruction of the nail.

• One variant of nail lichen planus is associated with trachyonychia.

The PCDS nail guidance says patients with potentially destructive lichen planus of the nails should be referred urgently to dermatology, because early intervention may prevent long-term nail damage. In its images it describes late-stage nail disease with longitudinal ridging and thinning as damage that is likely to be permanent and not responsive to treatment, and that patients with signs of nail damage should be referred early.

This is why unexplained thinning, splitting or ridging of several nails, especially with an itchy rash, mouth lacy white patches or genital symptoms, deserves a GP appointment rather than waiting to see if it improves.

The PCDS says the skin lesions are shiny, flat-topped violaceous papules with white lines (Wickham's striae) across the surface, and itch is usually very marked. The mouth is involved in approximately 50% of all LP cases, with a white lacework pattern, most commonly on the inside of the cheeks. Papules tend to flatten after a few months and be replaced by hyperpigmentation, which can be intense.

The PCDS advises that patients with oral LP should be advised to have an annual dental review, because squamous cell carcinoma is a rare consequence of mucosal lesions, particularly with erosive LP of the genitalia or mouth.

Many people have a few ridges in normal nails, according to the PCDS, and other causes of longitudinal ridging include peripheral vascular disease, a myxoid cyst, median nail dystrophy, habit-tic nail deformity and Darier's disease. Trachyonychia can also be idiopathic or associated with alopecia areata, psoriasis or ichthyosis vulgaris. A clinician looks at the skin, mouth and scalp as well as the nails to tell these apart.

The PCDS lists nail lichen planus among conditions in which nail disorders provide a major therapeutic challenge, which is why early recognition and specialist input matter. Treatment is chosen by a dermatologist, and the PCDS general nail measures include protecting hands from solvents and other chemicals, using plenty of emollients and avoiding manicures. Because nail damage can be permanent, the aim of early review is to limit lasting damage.

On the NHS the route is a GP appointment and urgent referral to dermatology if nail damage is suspected. Private dermatology can provide quicker assessment and biopsy where needed, and the principle of early review is the same. Take a note of how long nails have been changing and photographs showing progression, which help the specialist.