In pincer or trumpet nails, affected nails typically have an exaggerated transverse curvature. The condition may be hereditary, in which case the fingernails may also be involved. The main symptom is pain, as the lateral edges of the nails turn under and pierce the skin. Treatment is not always required, but if it is, the only way to relieve the pain is to excise the lateral edge of the nail on both sides. Permanent relief can only be obtained by removal of the nail and ablation of the nail bed to prevent regrowth.
An acute development of pain, redness and swelling of the lateral or posterior nail fold usually indicates underlying acute paronychia. The most important aetiological factor is a history of localised trauma, such as picking or biting. The cause is usually a localised Staphylococcus aureus infection, which may result in visible pus. Incision and drainage speeds recovery and reduces pain. In persistent cases, oral antibiotics may be required. In all cases, saline soaks and analgesia may help.
Following severe illness, transverse ridges may appear in the nails. The result of a temporary arrest in normal development in the matrix, Beau's lines usually affect all of the nails simultaneously. They are commonly seen after MI, sepsis or chemotherapy. In other cases where there has not been severe illness, they may indicate zinc deficiency.
No treatment is necessary, but patients should be advised that it may take many months for the ridges to grow out.
Chronic paronychia presents with a history of chronic red, tender swelling of the periungal tissue, with an absence of the cuticle. Loss of the protective barrier allows the entry of organisms. When the matrix is involved, transverse ridging can also develop.
The condition is more common in people whose hands are continually wet (nurses, cooks, florists) and where there is poor peripheral circulation (perniosis or chilblains).
Treatment depends on the type of infection involved.
Fungal nail infections are usually caused by Trichophyton rubrum. Once under the nail, the fungus spreads laterally and downwards towards the matrix. The nails become discoloured, dystrophic and brittle, separating from the nail bed with the development of a layer of keratin in between.
In superficial infection, a topical antifungal often helps, but in most cases, an oral form is required. For toenails, where the infection is most common, treatment for up to six months may be required.
When trauma occurs on a nail, bleeding may occur between the nail and the nail bed. This gives the nail a black appearance and because of the restricted space, the pressure can cause significant pain.
Draining the blood by making a hole in the nail gives instant relief. Where there is no history of trauma, an important differential diagnosis is subungual malignant melanoma. If in doubt, an urgent hospital appointment should be arranged for a biopsy.
- Dr Stollery is a GP in Kibworth, Leicestershire, and clinical assistant in dermatology, Leicester Royal Infirmary