Definition

Psoriasis is an autoimmune inflammatory condition that leads to an overproduction of skin cells in the body. These excess skin cells cause the formation of thick, itchy, and scaly plaques. Psoriasis can also manifest on joints and nails, particularly the fingernails. While it can develop on any part of the skin, it typically presents on the elbows, knees, lower back, and scalp.

Causes

Psoriasis is an autoimmune reaction in which the immune system's cells mistakenly identify parts of the body as foreign and attack them. The exact cause of nail psoriasis remains uncertain, although it is believed to develop due to a combination of the genetic, immune system, and environmental factors interacting with each other.

Nail psoriasis results from inflammation of the nail bed or nail matrix (the underside of the nail that is lighter in color than the rest).  This matrix inflammation then causes issues with the growth and shape of the nail itself.

Risk factor

Nail psoriasis can affect both children and adults. This disease affects men and women equally, but the risk increases with age. Nail psoriasis is usually associated with cutaneous psoriasis and psoriatic arthritis, but it can also develop as a sole manifestation without other symptoms. Nail psoriasis can develop alongside or after the onset of cutaneous psoriasis.

The body's immune system is the most suspected contributor of all the factors that can contribute to psoriasis. Psoriasis is usually inherited between biological family members. However, genetic factors in psoriasis are not yet known for certain.

Symptoms

Symptoms of nail psoriasis may vary among individuals, ranging from mild to severe, and may include:

Nail pitting

The hard surface of the nail is made of keratin, which is a hardened protein that can be found in skin and hair. Nail psoriasis causes this part of the nail to lose cells and form pits. These pits look like your nail was hit with the pointy end of a ballpoint pen. Some people can have just one pit on each fingernail, but others can have multiple pits on a single finger. The pits themselves can be shallow or deep.

Change in the shape and thickness of the nail.

Weakness of the nail structure may cause it to crumble. The nails may also become thicker due to onychomycosis or fungal infection, which is common in psoriasis patients. Not only that but nails could also thicken due to the growth of a chalk-like substance underneath, referred to as subungual hyperkeratosis. This condition can cause discomfort and pain.

Nail bed separation

Kuku juga dapat terlepas dari dasarnya, disebut sebagai onikolisis. Onikolisis meninggalkan ruang kosong yang seharusnya terisi kuku. Onikolisis dapat diawali dari perubahan warna kuku menjadi lebih kuning, kemudian diikuti oleh lepasnya kuku. Bakteri dapat masuk ke ruang kosong pada dasar kuku sehingga kuku menjadi berwarna lebih gelap

Nails may also detach from its base, this condition is referred to as onycholysis. Onycholysis leaves an empty space that would otherwise be filled with nail. Onycholysis may start with yellow discoloration of the nail, followed by detachment of the nail. Bacteria could enter the empty space at the nail bed causing the nail to become darker in color.

Change of nail color

Nail color may also change. This change can be observed as a yellow-reddish color that looks like a drop of oil. Nail can also look like a red half-moon at the bottom of the nail, caused by dilated blood vessels. There may also be red-purplish stripes on the nail. Meanwhile, the nail itself may turn to a yellow-brownish color.

Blood spots

Blood spots may also be found under your skin.

Rough nails

One or all of your nails could look like sandpaper; this condition is called trachyonychia.

Diagnosis

To diagnose nail psoriasis, doctors may look for signs and symptoms of psoriasis on the skin and joints. Cutaneous psoriasis rash looks red, itchy, and has scaly plaques on the skin. Meanwhile, psoriatic arthritis can have symptoms of redness and swelling in the joints, especially the joints in the fingers and toes.

Nail psoriasis can also be diagnosed by observing the shape of the nails. However, doctors may also perform a skin scraping technique to search for fungal infections, as onychomycosis (fungal infection of the nails) resembles psoriasis. Also, if the diagnosis is difficult to confirm, doctors may take tissue samples from the nail bed (biopsy) to observe with a microscope.

Management

Dermatologists use the same management method for nail psoriasis, just like cutaneous psoriasis. Nail psoriasis can be challenging to treat and treatment takes time to provide effective results. Treatment may include:

Topical medications

Topical medications come in various forms, including ointments, creams, emulsions (fat in water or water in fat), and similar to nail polish. These topical medications may include corticosteroids to reduce inflammation caused by psoriasis. Meanwhile, vitamin D can help reduce inflammation while slowing the growth of excess skin cells. Nail thickening may be reduced by decreasing cell buildup under the nail. In addition, vitamin A derivatives such as retinoids can also be used to restore nail color, nail pits and detachment.

Corticosteroid injections 

In certain cases, doctors may prescribe corticosteroid injections near nails. These injections can treat symptoms such as nail thickening, ridges in the nails, and skin separation.

Oral medications 

If topical medications do not work, doctors could prescribe oral medications. These medicines contain substances that can lower the body's immune system, making you more susceptible to infection. Therefore, these medications need to be discussed with your doctor before use.

Phototherapy

Phototherapy can prevent nail separation and discoloration by slowing down the cell growth of nails. For nail psoriasis, this therapy is called PUVA (photochemotherapy). It involves soaking your hands with a liquid called psoralen. This medication can also be an oral medication. Psoralen makes your skin more sensitive to UVA (ultraviolet A) light. After taking the drug, your nails will be irradiated by UVA light, which can come from sunlight, phototherapy (light therapy) units in healthcare facilities, or lasers.

Laser therapy

Meanwhile, laser therapy is performed using a laser that converts light energy into heat. It targets the blood vessels under the skin with a light beam, thereby preventing detached nails and subungual hyperkeratosis.

Complications

Complications of nail psoriasis can occur due to the course of the disease or as a result of therapy. These complications may include:

• Certain functional disability 
• Psychological distress
• Infections (including bacterial and fungal infections)
• Acute or chronic skin infections around the nail (paronychia), and onychomycosis.

Prevention

If you have psoriasis, you can do the following to prevent the recurrence of nail psoriasis:

• Keep your nails short to avoid injury or nail separation from the bed. Trimming your nails regularly will also help prevent buildup from collecting underneath the nail cells.
• Avoid biting or picking at your nails and pushing back your cuticles. Injuries to the skin could increase the risk of psoriasis flares, which is called the Koebner phenomenon.
• Wear gloves when you do water-related activities such as gardening or washing dishes. For the best protection, wear cotton gloves under vinyl or nitrile gloves.
• Keep your nails clean and dry to prevent infection.
• Use a moisturizing cream on your nails and the surrounding skin. This can help prevent cracked skin and brittle nails.
• Avoid cleaning your nails with a brush or sharp object to prevent nail separation.
• If you smoke, try to quit. Smoking can increase the risk of psoriasis
• If you drink, try to drink in moderation. Alcohol is associated with a higher risk of psoriasis.

When to see a doctor?

If your nails suddenly change in color or shape and fall off easily, you can visit a doctor. In addition, you can also consult a doctor if you experience psoriasis symptoms such as reddish, itchy, and scaly plaques on your body, especially on the elbows, knees, lower back, and scalp.