Nail psoriasis is a special form of psoriasis in which the nails of the hands and / or feet are affected. Doctors call this type of disease psoriatic onychodystrophy (from the Greek.onychosis- nail,dis- violation,trophy- food).
In this article you will learn about the causes of the development of nail psoriasis, its symptoms, which do not always unambiguously indicate the correct diagnosis, as well as dangerous misconceptions about this form of the disease.
Note.There are many photos in the article that can scare the unprepared reader.
Where do nails grow?
To understand the problem of nail psoriasis, it is important to understand how the so-called nail device works.
The nail has two functions: working and aesthetic. First, the nail protects the fingertips from damage, increases accuracy and sensitivity when working with small objects, can be a weapon of attack or defense, and finally, with the help of nails that itch. Secondly, the aesthetic or cosmetic function of the nails is also important, especially for women.
The nails are formed by the outer layer of the skin - the epidermis. The nail apparatus includes:
- nail plate - directly the nail itself,
- matrix - produces the nail plate,
- the nail hole, or lunula, is the only visible part of the matrix, this is a white lunar area at the base of the nail plate,
- eponychium - a nail roller that protects the matrix from damage from above,
- nail bed - is located under the nail plate and is responsible for attaching it to the nail phalanx of the finger,
- hyponichium - the transitional area between the nail bed and the skin at the tip of the finger.
Causes and mechanism of development of nail psoriasis
In its course - with periodic exacerbations and remissions - nail psoriasis resembles a vulgar form of the disease.
Nail psoriasis is thought to develop for the same reasons and in the same pattern as typical psoriatic eruptions. Among these reasons, a distinction is made between external and internal factors.
The main internal factor is genetic predisposition. External causes are numerous and include, for example, injuries, poor diet, narcotics (alcohol and tobacco), infections and certain medications.
The standard mechanism of development of nail psoriasis under the influence of these causes can be briefly described as follows:
- Provoking factors, such as trauma, activate immune cells.
- Activated immune cells migrate to the area of the nail matrix or nail bed.
- Immune inflammation develops in these areas.
- The division of skin cells is sharply accelerated and their maturation is impaired.
- There are characteristic symptoms of psoriasis on the nails.
Also, the cause of nail psoriasis can be considered as a result of the body's inability to adapt to adverse environmental conditions. According to this view, the main cause of psoriasis is an evolutionary alien habitat.
As a result, this evolutionary approach considers unhealthy diet, lack of sun and clean water, excess toxins, lack of normal physical activity, sleep disorders and chronic stress as direct causes of the disease.
Nail psoriasis and psoriatic arthritis are related
The link between nail damage and psoriatic arthritis has long been known.
Based on observations, the researchers found that psoriatic arthritis was accompanied by nail damage in nine out of ten cases.
But the mechanism of this relationship has not been fully studied. The authors of several studies, for example from the Institute of Molecular Medicine in Leeds (UK), try to explain this relationship outside the concept of immune inflammation.
According to them, the fact is that the finger joint is located next to the nail and is anatomically connected to it.
Therefore, microtraumas and the Kebner phenomenon, which cause primary inflammation of the joints - psoriatic arthritis - also cause secondary pathological changes in the nearest nail.
This is why psoriatic arthritis is so often associated with nail damage.
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Thus, the symptoms of nail psoriasis are often indicative of psoriatic arthritis.
Let's now look at the main myths that accompany this disease and how dangerous they are.
Myth 1: Nail psoriasis is rare.
Not exactly. Obviously, nails suffer from psoriasis very often.
According to various sources, nail psoriasis occurs in the range of 6% to 82% of cases of psoriasis vulgaris. Such wide distribution in the assessment of the prevalence of this pathology is explained by problems in its reporting. Medical statistics record visits to doctors in the first place by patients with vulgar form, and in the second place attention is paid to the nails. In research, cases of nail psoriasis are also usually studied only in addition to the main object of interest - psoriasis with skin lesions.
However, a number of publications say so
up to 80-90% of patients with psoriasis vulgaris report recurrent nail damage.
And also that nail psoriasis occurs in 90% of patients with psoriatic arthritis and scalp psoriasis.
It should be noted that adults usually suffer from this form of the disease.
According to various sources, in children, nails are affected in about 7-37% of cases of psoriasis. Unfortunately, often the manifestations of psoriasis on the nails of a child are not given due importance. Parents or doctors believe that this is a variant of the norm or a consequence of trauma, or simply do not notice due to the mild severity of symptoms.
Myth 2: Recognizing nail psoriasis by symptoms is easy
In fact, not always. The fact is that
the nail is able to respond to various diseases with only a limited number of symptoms. Therefore, the manifestations of different nail diseases may look the same.
Of course, nail psoriasis may be suspected if the patient has severe symptoms of psoriasis vulgaris. However, nail lesions can be minor compared to skin lesions and can easily be ignored by a doctor.
Usually, the more active the psoriasis on the skin, the more severe the nail damage.
The nails are affected in the first place.
And it is also important to know that in 5% of cases, nails may be the only initial manifestation of psoriasis. That is, the classic manifestations of psoriasis on the skin may be completely absent.
What psoriasis of the nails looks like depends on where the pathological changes originate - in the matrix or the bed of the nail.
When choosing treatment, it is important to consider the source of symptoms - matrix or bed. It is therefore necessary to define it correctly.
The symptoms that originate from the nail matrix are:
- thimble symptom
- white spots and spots (leukonychia),
- red dots on the hole,
- crumbling nails.
Although the cause of these symptoms is at the level of the matrix, as the nail grows, pathological changes appear on the nail plate.
The symptoms, the cause of which is in the nail bed, are:
- nail detachment (onycholysis),
- longitudinal hemorrhage,
- subungual hyperkeratosis,
- symptom of an oil stain.
Then we will focus on each symptom separately. And let's start with the manifestations that originate from the matrix.
Thimble symptom
The thimble symptom appears on the surface of the nail plate with holes or pits that look like dents in the thimble.
Such defects occur mainly on the nails, but rarely on the feet. As the nail grows, the pits move from the nail fold to the edge of the nail plate.
The pits in nail psoriasis are usually deep, large and chaotic. They occur due to the detachment of loose clusters of cells from the surface of the nail, in which division and keratinization are impaired.
The more severe the psoriasis, the more common the thimble symptom.
However, it should be borne in mind that in addition to psoriasis, the pits on the nails are also characteristic of alopecia areata (alopecia), eczema, dermatitis and can occur, for example, in fungal infections.
Counting the total number of pits on all nails will help make the correct diagnosis.
- Less than 20 - not typical of psoriasis,
- from 20 to 60 - psoriasis may be suspected,
- more than 60 - confirm the diagnosis of psoriasis.
White spots (leukonychia)
Leukonychia is a symptom that manifests as white spots or spots on the nails.
With leukonychia (from Greek.leukós- white andonychosis- the nail), in contrast to the superficial fossae in the thimble symptom, the cells with impaired division and keratinization are located in the thickness of the nail plate. At the same time, the surface of the nail remains smooth. And the white color of spots arises from the reflection of light from clusters of freely located cells.
However, some studies show that leukonychia is so common in healthy people that it is not a distinctive symptom of psoriasis. For example, a manicure injury can cause leukonychia.
Falling nails
When the superficial pits (a symptom of the thimble) and the deep areas of leukonychia (white spots) merge, the nails begin to crumble.
Nail fragmentation usually occurs with long-term nail psoriasis.
And the more intense the inflammation of the nail matrix, the more the nail plate is destroyed. In severe cases, the nail may completely collapse and fall off.
Red dots on the nail socket
Apparently, the red spots in the area of the hole and its general redness appear due to increased blood flow to the vessels under the nail.
Also, the red dots on the hole are formed due to a violation of the structure of the nail plate itself: it becomes more transparent and thinner. And because of this, firstly, the vessels become more visible, and secondly, the thin nail plate puts less pressure on the vessels below it and they are more full of blood.
Thinning of the nail plate can also cause redness of the entire nail bed.
Nail detachment (onycholysis)
Now let's look at the symptoms, the source of which is the nail bed.
Onycholysis is the separation of the nail plate from the bed due to the accumulation of cells under the nail with impaired division and keratinization.
Onycholysis itself (from Greek.onychosis- her nailλύσις- separation) is not necessarily a sign of psoriasis and can develop, for example, as a result of nail injury.
Initially, the loss of contact between the nail and the bed occurs in the area of hyponychia - on the outer edge of the nail plate. The onycholysis then spreads to the nail fold in the form of a semicircular line. The exfoliation area becomes white due to the accumulation of air under the nail.
A reddish border (scientifically erythema) on the edge of onycholysis, which is usually seen on the fingers, is characteristic of psoriasis and helps to make the correct diagnosis.
With prolonged onycholysis, the nail bed loses its properties and the growing new nail will most likely not be able to attach to it normally. Therefore, even with complete renewal of the nail plate, onycholysis often continues.
Due to the fact that onycholysis facilitates the penetration of bacteria and fungi, infection can join. This sometimes leads to discoloration of the nail. For example, when bacteria attach, a greenish color may appearPseudomonas aeruginosa(Pseudomonas aeruginosa) and others.
Longitudinal subungual hemorrhage
Longitudinal subungual hemorrhages appear in the nail bed and look like dark red lines 1-3 mm long.
Increased blood flow and swelling in the area of inflammation of the nail bed lead to rupture of the capillaries, which manifests itself in the form of such hemorrhages.
Due to the peculiarities of the blood supply, most hemorrhages occur closer to the free edge of the nail - in the area of hyponychia.
Subungual hyperkeratosis
Subungual hyperkeratosis is an accumulation of dead cells under the outside of the nail plate.
In psoriasis, subungual hyperkeratosis (from the Greek.hyper- excessive andkeri- horn) is usually silvery white in color, but can also be yellow. And when the infection joins, it can become, for example, greenish or brown.
The more the nail is raised above the nail bed, the higher the activity of the pathological process.
On the fingers, subungual hyperkeratosis usually manifests itself in loose layers under the nail plate. On the feet these tables are tightly welded with a thickened toenail.
Also, psoriasis with toenail lesions is characterized by a combination of subungual hyperkeratosis with onycholysis (separation of the nail).
Symptom of an oil stain
The symptom of an oil stain appears under the nail plate in spots of yellow-red (salmon) color.
They occur on the nail bed closer to the nail fold and move to the edge of the nail as it grows.
The cause of this symptom is inflammation of the nail bed with dilation of capillaries and accumulation of cells involved in inflammation, as well as cells with impaired division and keratinization.
Oil stains are available in various shapes and sizes. They can be found both in the center of the nail and on the edge, next to the area of onycholysis.
Myth 3: Nail psoriasis is just a cosmetic problem.
In fact, this is not true. Although over 90% of patients report ugly nail psoriasis, it is not just a cosmetic problem.
According to various studies, nail psoriasis significantly reduces the quality of life of patients:
- 52% of patients also complain of pain,
- 59% - for problems in daily activities,
- 56% - for difficulties at home and
- 48% - for work difficulties.
That is why it is very important to make the correct diagnosis and start treatment as early as possible, as improving the condition of the nails significantly improves the quality of life of patients with psoriasis.
Myth 4: Nail psoriasis is not dangerous
In fact, this is not the case. Talking above about the causes of this form of the disease, we have already written it
nail psoriasis is an important symptom of psoriatic arthritis.
It is important to keep in mind that the external manifestations of arthritis may be completely absent. In this case, we can talk not only that the joints of the fingers and toes are affected, but also the joints of the spine and pelvis can be affected.
You can check your joints for arthritis with ultrasound (ultrasound) or magnetic resonance imaging (MRI).
Even if there are no obvious symptoms of arthritis, but there are signs of nail psoriasis, it is very important to make sure that all joints are in order.
And then regularly monitor the condition of the joints. Otherwise, psoriatic arthritis can be easily missed! Late diagnosis will lead to late treatment and as a result to irreversible joint damage and injury.
Therefore, if the doctor has not ordered tests for insurance, citing the absence of visible signs of arthritis, you should contact the clinic yourself and undergo, for example, an ultrasound scan on a paid basis.
How to diagnose nail psoriasis
It is important to be able to recognize the many symptoms of nail psoriasis that we have described above, as they help to establish the correct diagnosis. But because nail changes characteristic of psoriasis can occur in other diseases, it can be difficult to make a correct diagnosis right away.
In this case, the presence of several symptoms simultaneously on different nails can help in the diagnosis.
Important signs of nail psoriasis are:
- thimble symptom: more than 20 pits on all fingernails indicate the possibility of psoriasis, and more than 60 pits confirm the diagnosis of psoriasis,
- peeling of the nail (onycholysis) with a reddish border around the edge,
- oil stains (salmon) on the nail bed.
Difficulty in diagnosing nail psoriasis by one symptom
It is especially difficult to diagnose nail psoriasis if it occurs with only one symptom.
For example, if only onycholysis of the hands or only subungual hyperkeratosis of the hands and / or feet occurs.
The only method for making a reliable diagnosis of isolated onycholysis (peeling of the nails) is probably the examination of hyponychia using a special microscope - a dermatoscope.
A high magnification dermatoscope video magnification is used for this. Please note that the hand-held dermatoscope does not provide the required magnification. A video dermatoscope with a magnification of at least 40 times is required. Then the dilated capillary loops characteristic of psoriasis become visible.
In isolated subungual hyperkeratosis, the likelihood of psoriasis is high if the accumulation of scales under the nail is whitish-silvery in color, and if all fingernails or toenails are affected.
Psoriasis or nail fungus?
Approximately 30% of patients with nail psoriasis also have a fungal infection - scientifically onychomycosis.
Externally, hyperkeratosis and onycholysis (nail discharge) in psoriasis may resemble the manifestations of a fungal infection. Therefore, it may be difficult to make a differential diagnosis, ie to identify the true cause of changes in the nail plate.
In addition, both psoriasis and fungus can affect the same nails at the same time. It most often appears on the toes and is characteristic mainly of older patients.
Also, in a fungal infection, one or both nails of the big toes are often affected. Psoriasis usually affects several nails at once.
The following symptoms speak in favor of psoriasis:
- oil stains and / or thimble nail symptom,
- signs of psoriasis on the scalp and / or large folds of skin,
- periodic remission and exacerbation of nail damage.
In favor of onychomycosis, they say:
- longitudinal stripes on the affected nail,
- detection of fungi during examination under a microscope of scrapings treated with potassium hydroxide from the affected nail (KOH test),
- positive fungal culture.
In general, based only on external manifestations, it is impossible to completely rule out a fungal nail infection in patients with psoriasis.
It should also be remembered that fungal infection can cause the Kebner phenomenon on the nail and surrounding skin, leading to symptoms of psoriasis. Anyway
it is useful to go to a mycologist and get tested for fungus and if you find yourself, start antifungal therapy.
Important discoveries and what to do
Let's summarize important information about nail psoriasis and its symptoms.
Diagnostic features:
- Nail psoriasis is very common but often overlooked.
- Manifestations of nail psoriasis can be insignificant, so even experts often do not pay attention to it.
- In 5% of cases, nail damage may be the only symptom of incipient psoriasis.
- The manifestations of different nail diseases may look the same, which further complicates the diagnosis.
The main manifestations of nail psoriasis:
- thimble symptom - pits on the nail,
- white dots,
- crumbling nails
- red dots in the area of the hole,
- peeling of the nail,
- longitudinal subungual hemorrhage,
- subungual hyperkeratosis - loose clusters under the nail,
- symptom of an oil stain.
Psoriasis and fungus:
- Often, nail psoriasis is accompanied by a fungal infection.
- To rule it out unambiguously, it is necessary to contact a mycologist and conduct additional tests.
Nail psoriasis and psoriatic arthritis:
- Nail psoriasis is a common companion of psoriatic arthritis.
- It is important to detect pathological changes in the joints as early as possible to start treatment on time and to avoid irreversible complications and damage.
- Even if there are no external symptoms of arthritis, but psoriasis of the nails is detected, it is necessary to undergo an examination of the joints with the help of ultrasound or MRI.