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Deformities, Dystrophies, and Discoloration of the Nails

By

Chris G. Adigun

, MD, Dermatology & Laser Center of Chapel Hill

Last full review/revision Dec 2019| Content last modified Dec 2019
Click here for the Professional Version
Topic Resources

The terms deformities and dystrophies are often used interchangeably, sometimes even by doctors. However, their meanings are slightly different.

  • Deformities: Changes in nail shape

  • Dystrophies: Changes in nail texture, color, or both

About 50% of nail dystrophies are caused by a fungal infection (onychomycosis Onychomycosis Onychomycosis is a fungal infection of the nails. (See also Overview of Nail Disorders.) About 10% of people have onychomycosis, which most often affects the toenails rather than the fingernails... read more Onychomycosis ) . The remainder result from various causes, including nail injuries Fingernail and Toenail Injury Even a minor injury to the finger may cause changes in the nail. The nail may develop a small spot of white discoloration that starts at the injured location and grows out with the nail. Severe... read more Fingernail and Toenail Injury , birth deformities of the nails Birth deformities of the nail The terms deformities and dystrophies are often used interchangeably, sometimes even by doctors. However, their meanings are slightly different. Deformities: Changes in nail shape Dystrophies... read more Birth deformities of the nail , psoriasis Psoriasis Psoriasis is a chronic, recurring disease that causes one or more raised, red patches that have silvery scales and a distinct border between the patch and normal skin. A problem with the immune... read more Psoriasis , lichen planus Lichen Planus Lichen planus, a recurring itchy disease, starts as a rash of small, separate, red or purple bumps that then combine and become rough, scaly patches. The cause may be a reaction to certain drugs... read more Lichen Planus , and occasionally tumors (cancerous and noncancerous). Drugs, infections, and diseases can cause discoloration of the nails (chromonychia). For example, infection with Pseudomonas bacteria can cause a greenish discoloration (see Green Nail Syndrome Green Nail Syndrome Green nail syndrome is infection with Pseudomonas, a type of bacteria. (See also Overview of Nail Disorders.) The photo on the left shows green nail syndrome with onycholysis of the fourth fingernail... read more Green Nail Syndrome ).

The doctor can often make the diagnosis of nail dystrophies caused by a fungus by examining the nails. However, to confirm the diagnosis, the doctor may need to take fungal scrapings and do a culture (the process of growing the organisms in a laboratory) or do a polymerase chain reaction (PCR) analysis to look for genetic material from a fungus.

To diagnose nail dystrophies that are not caused by a fungus, doctors may do a biopsy of the nail plate (the hard part of the nail) or nail matrix (located at the base of the nail and where nail growth originates).

If the nail’s appearance does not improve with treatment of the underlying disorder, manicurists may be able to hide deformities and some dystrophies with appropriate trimming and polishes.

Birth deformities of the nail

Some babies are born without nails (anonychia). In nail-patella syndrome Nail-Patella Syndrome Nail-patella syndrome is a rare hereditary disorder that results in abnormalities of the kidneys, bones, joints, toenails, and fingernails. Nail-patella syndrome is caused by a mutation of a... read more , thumbnails are missing or are small with pitting and ridges. Darier disease causes red and white streaks on the nails and V-shaped notches to form on the tips of the nails. In pachyonychia congenita, nail beds (the parts of the nail unit that attach the nail to the finger) are thickened and discolored and are curved from side to side, forming a pincer nail deformity Pincer nail deformity The terms deformities and dystrophies are often used interchangeably, sometimes even by doctors. However, their meanings are slightly different. Deformities: Changes in nail shape Dystrophies... read more Pincer nail deformity .

Nail deformities and dystrophies associated with systemic diseases

Sometimes, diseases that involve other organs (systemic diseases) can cause changes in the nails as well, including the following:

Examples of Nail Deformities and Dystrophies Associated With Systemic Diseases

Deformities and dystrophies associated with skin diseases

Sometimes, skin diseases also affect the nail unit and may change the appearance of the nails. Some drugs given to treat skin diseases can change the nail plate. For example, retinoids, such as isotretinoin and etretinate, can cause dryness and brittleness of the nails.

Examples of Nail Deformities and Dystrophies Associated With Skin Diseases

Effect of drugs on nails

Drugs may cause other nail problems, such as melanonychia striata (brown or black pigmented lines) and onycholysis. Different drugs lead to discoloration of the nail, which usually gets better after the drug is stopped and the nail grows out.

Median nail dystrophy

In median nail dystrophy, small cracks in the center of the nail extend to the sides and eventually look like the branches of an evergreen tree (such as a Christmas tree). The cause of median nail dystrophy is unknown in some cases, but repeated injuries, including frequent use of computer keyboards and similar devices, are thought to play a role. The person must stop injuring the nails. Treatment with tacrolimus ointment has been shown to help in some cases.

Melanonychia striata

Melanonychia striata are gray, brown, or black lines in the nail plate caused by the normal, brown skin pigment, melanin. The lines extend from the base of the nail to its tip. In dark-skinned people, these lines may be normal and require no treatment. Other noncancerous causes of melanonychia striata include moles Moles Moles are small, usually dark, skin growths that develop from pigment-producing cells in the skin (melanocytes). Most people have some moles, but the tendency to develop atypical moles is sometimes... read more Moles , HIV infection Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and can cause acquired immunodeficiency syndrome (AIDS). HIV is transmitted... read more Human Immunodeficiency Virus (HIV) Infection , hyperthyroidism Hyperthyroidism Hyperthyroidism is overactivity of the thyroid gland that leads to high levels of thyroid hormones and speeding up of vital body functions. Graves disease is the most common cause of hyperthyroidism... read more Hyperthyroidism , use of certain drugs, pregnancy, nail injuries Fingernail and Toenail Injury Even a minor injury to the finger may cause changes in the nail. The nail may develop a small spot of white discoloration that starts at the injured location and grows out with the nail. Severe... read more Fingernail and Toenail Injury , Addison disease Addison Disease In Addison disease, the adrenal glands are underactive, resulting in a deficiency of adrenal hormones. Addison disease may be caused by an autoimmune reaction, cancer, an infection, or some... read more Addison Disease , and Cushing syndrome Cushing Syndrome In Cushing syndrome, the level of corticosteroids is excessive, usually due to taking corticosteroid drugs or overproduction by the adrenal glands. Cushing syndrome usually results from taking... read more Cushing Syndrome .

However, similar dark lines or discoloration in or around a nail can be an early sign of cancer, particularly melanoma Melanoma Melanoma is a skin cancer that begins in the pigment-producing cells of the skin (melanocytes). Melanomas can begin on normal skin or in existing moles. They may be irregular, flat or raised... read more Melanoma , which can develop from the pigment cells of the nail-making tissue (nail matrix). Doctors usually do a biopsy of the nail matrix if they are concerned a discoloration might be cancerous.

Onychogryphosis

Onychogryphosis is a dystrophy in which the nail, most often on the big toe, becomes thickened and takes on an extremely curved, hooked appearance (ram’s horn nail). The curved hooked nail may injure an adjoining toe and is caused by one side of the nail growing faster than the other. This disorder involves damage to the nail bed, which is most often caused by repetitive injury (such as by ill-fitting shoes) but may also occur in disorders such as psoriasis Psoriasis Psoriasis is a chronic, recurring disease that causes one or more raised, red patches that have silvery scales and a distinct border between the patch and normal skin. A problem with the immune... read more Psoriasis . Onychogryphosis is common among older people. The nails should be kept trimmed, and injury to nearby toes can be prevented by placing lamb’s wool between the toes. Footwear or stockings that gather at the toes should be avoided.

Onycholysis

Onycholysis is partial separation of the nail plate from the nail bed or complete nail plate loss. It can result from

Additionally, other drugs, such as doxycycline, psoralens, and fluoroquinolones, can cause onycholysis after nails are exposed to sunlight (photo-onycholysis).

People with onycholysis are at risk of infection with yeast and fungus. Keeping the nail dry and applying antifungal preparations to the nail unit can help.

Onychotillomania

People with this disorder pick at and tear their nails Body-Focused Repetitive Behavior Disorder In body-focused repetitive behavior disorder, people repeatedly engage in activities that involve their body, such as nail biting, lip biting, or cheek chewing, and repeatedly try to stop the... read more . The most common manifestation is the habit-tic deformity, in which the person frequently picks at or rubs the central cuticle (the skin at the base of the nail) with a neighboring finger. This manifestation is most often seen on the thumbnail and leads to a washboard-like appearance in the center of the nail plate. Onychotillomania can also cause bleeding beneath the nails (subungual hemorrhage), infection in the nail unit, and even complete loss of the nail plate.

Pincer nail deformity

In pincer nail deformity, the nail is overcurved horizontally (side-to-side). It is most often caused by a fungal infection (onychomycosis Onychomycosis Onychomycosis is a fungal infection of the nails. (See also Overview of Nail Disorders.) About 10% of people have onychomycosis, which most often affects the toenails rather than the fingernails... read more Onychomycosis ), psoriasis Psoriasis Psoriasis is a chronic, recurring disease that causes one or more raised, red patches that have silvery scales and a distinct border between the patch and normal skin. A problem with the immune... read more Psoriasis , tumors of the nail Tumors of the Nails Noncancerous (benign) and cancerous (malignant) tumors can affect the nail unit, causing a changes in nail texture and/or color (dystrophy). Noncancerous tumors include myxoid cysts (benign... read more Tumors of the Nails , and poorly fitting shoes. The deformity can also occur in people who have lupus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more Systemic Lupus Erythematosus (SLE) , Kawasaki disease Kawasaki Disease Kawasaki disease causes inflammation of blood vessels throughout the body. The cause of Kawasaki disease is unknown but may be associated with an infection. Children typically have fever, rash... read more Kawasaki Disease , end-stage renal disease (severe chronic kidney disease Chronic Kidney Disease Chronic kidney disease is a slowly progressive (months to years) decline in the kidneys’ ability to filter metabolic waste products from the blood. Major causes are diabetes and high blood pressure... read more ), and some genetic syndromes (for example, pachyonychia congenita). Sometimes it develops in older people and in those with arthritis in their fingers. People often have pain where the nail plate curves into the tips of the fingers.

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Psoriasis
Psoriasis is a common chronic disease affecting 1 to 5% of the population worldwide. It causes distinctive raised, red patches with silvery scales. A border between the patch and normal skin is known as “psoriatic plaque.”  Which of the following is the reason these patches of plaque form?
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