Pincer nail

Pincer nails are a toenail disorder in which the lateral edges of the nail slowly approach one another, compressing the nailbed and underlying dermis. It occurs less often in the fingernails than toenails, and there usually are no symptoms.

Hereditary pincer nails have been described although the genes or mutations causing the hereditary form seem to be unknown.

Signs and symptoms
Pincer nail is characterized by an increase in the maximum transverse curvature, which pushes the nail edges down into the lateral nail fold, as well as thickening and narrowing of the nail bed at the distal end along the longitudinal axis of the nail plate in a proximal to distal manner. Affected patients' daily lives are negatively impacted by the curvature that rises along the distal sides of the nail, resulting in excruciating pain, persistent inflammation, and recurring infections.

Causes
Pincer nails cause is unknown, although it may be acquired or inherited. There have been several reports of hereditary pincer nails. Acquired pincer nails are asymmetrical in contrast to inherited pincer nails. Pincer nails are linked to a number of systemic conditions, such as amyotrophic lateral sclerosis, renal failure, gastrointestinal cancers, Kawasaki disease, and systemic lupus erythematosus.

Diagnosis
The diagnosis of pincer nails in clinical. Differential diagnoses are necessary because pincer nails and ingrown nails differ in ways that are confounding despite having clinical similarities. Whereas pincer nails are recognized by their morphology, ingrown nails are recognized by their symptoms. The biggest physical distinction between pincer and ingrown nails is that the former have a transverse curve of the long axis of the nail plate that grows from proximal to distal. Additionally, the contour of the nail plate in ingrown nails stays normal while the nail steadily grows in height.

Treatment
Correcting the curvature that pinches the fingers and toes in order to produce a nail that is aesthetically normal is the goal of pincer nail treatment. There is no established course of treatment for pincer nails, despite the use of conservative, surgical, and combination therapies. Conservative treatment is associated with recurrence/temporary remission and is a straightforward procedure. On the other hand, although the surgical treatment has a decreased rate of recurrence, it comes with a price: extreme pain, an unattractive appearance, secondary infection, wound necrosis, and sensory disruption.

Epidemiology
Pincer nail has an incidence rate of about 0.9% and usually affects the hallux toenails on the outer, inside, and bilateral sides; fingernails and other toenails are rarely affected.