Nail psoriasis is a special form of psoriasis in which the fingernails and / or toenails are affected. Doctors call this type of disease psoriatic onychodystrophy (from the Greek.onychos- nail,dys- violation,trophy- food).
From 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.
To note.There are many photographs in the article that may frighten an unprepared reader.
Where do nails grow from?
To understand the problem of nail psoriasis, it is important to understand how the so-called nail appliance works.
The nail has two functions: functional and aesthetic. First, the nail protects the fingertips from damage, increases precision and sensitivity when working with small objects, it can be a weapon of attack or defense, and finally, with the help of nails, weitch. Secondly, the aesthetic or cosmetic function of the nails is also important, especially for women.
Nails are formed from the outer layer of the skin - the epidermis. The nail device includes:
- nail plate - directly the nail itself,
- matrix - it produces the nail plate,
- the nail hole, or lunula, is the only visible part of the matrix, it is a white moon shaped area at the base of the nail plate,
- eponychium - a nail roller that protects the matrix from above from damage,
- nail bed - located under the nail plate and is responsible for its attachment to the fingernail phalanx,
- hyponychium - the transition zone between the nail bed and the skin of the fingertip.
Causes and mechanism of development of nail psoriasis
In its course - with periodic exacerbations and remissions - psoriasis on the nails looks like a vulgar form of the disease.
Nail psoriasis is thought to develop for the same reasons and in the same pattern as typical psoriatic rashes. Among these reasons, we distinguish between external and internal factors.
The main intrinsic factor is genetic predisposition. The external causes are numerous and include, for example, injuries, poor diet, intoxicants (alcohol and tobacco), infections and certain medications.
The standard mechanism of development of psoriasis of the nails under the influence of these reasons 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 greatly accelerated and their maturation is disturbed.
- There are characteristic symptoms of psoriasis on the nails.
Also, the cause of nail psoriasis can be seen as the result of the body's inability to adapt to adverse environmental conditions. According to this view, the main cause of psoriasis is an evolving alien habitat.
As a result, this evolutionary approach considers an unhealthy diet, lack of sunlight and clean water, excess toxins, lack of normal physical activity, sleep disturbances and chronic stress as the direct causes of the disease. .
Nail psoriasis and psoriatic arthritis are linked
The link between nail damage and psoriatic arthritis has long been known.
Based on observations, scientists found that psoriatic arthritis was accompanied by nail damage in nine out of ten cases.
But the mechanism of this connection has not been fully investigated. However, the authors of several studies, for example from the Institute of Molecular Medicine in Leeds (UK), have attempted to explain this link beyond the concept of immune inflammation.
In their opinion, the fact is that the finger joint is located next to the nail and is anatomically associated with it.
Therefore, microtrauma and Kebner's phenomenon that 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 psoriasis of the nails are often indicative of psoriatic arthritis.
Now let's look at the main myths that accompany this disease and how dangerous they are.
Myth 1: Nail psoriasis is rare.
Not really. Apparently, with psoriasis the nails suffer very often.
According to various sources, nail psoriasis occurs between 6% and 82% of cases of psoriasis vulgaris. Such diffusion in the evaluation of the prevalence of this pathology is explained by problems of accounting. Medical statistics record visits to doctors primarily by patients with a common form, and attention is paid to fingernails second. In scientific research, cases of nail psoriasis are usually only studied in addition to the main object of interest - psoriasis with skin lesions.
However, a number of publications say that
up to 80-90% of patients with psoriasis vulgaris have reported recurrent nail lesions.
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, the nails are affected in about 7-37% of cases of psoriasis. Unfortunately, the manifestations of psoriasis on the nails of a child are often not taken into account. Parents or doctors think it is a variation of the norm or a consequence of trauma, or they simply do not notice it due to the mild severity of the symptoms.
Myth 2: Recognizing nail psoriasis by its symptoms is easy
In fact, not always. The fact is that
the nail is only able to respond to various diseases with a limited number of symptoms. Therefore, the manifestations of various diseases on the nails may resemble each other.
Of course, nail psoriasis can be suspected if the patient has severe symptoms of psoriasis vulgaris. However, nail damage can be minor compared to skin damage and can easily be ignored by a doctor.
Usually, the more active the psoriasis is on the skin, the more severe the damage to the nails.
First of all, the nails are affected.
And it's also important to know that in 5% of cases, the fingernails may be the only initial manifestation of psoriasis. That is, the classic manifestations of psoriasis on the skin may be completely absent.
The appearance of psoriasis of the nails depends on the origin of pathological changes - in the matrix or the nail bed.
The source of the symptoms - matrix or bed - is important to consider when choosing a treatment. Therefore, it is necessary to define it correctly.
The symptoms that arise from the nail matrix are:
- thimble symptom,
- white spots and dots (leuconychia),
- red dots on the hole,
- crumbling nails.
Although the cause of these symptoms is in 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:
- detachment of the nail (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 come from the matrix.
Thimble symptom
The symptom of a thimble appears on the surface of the nail plate with holes or pits, which look like depressions in a thimble.
These defects mainly occur on the nails, but they rarely appear on the feet. As the nail grows, the pits move from the crease of the nail to the edge of the nail plate.
The pits in nail psoriasis are usually deep, large, and chaotic. They occur due to the flaking of loose cell clusters on the surface of the nail, in which division and keratinization are impaired.
The more severe the psoriasis, the more often the thimble symptom will occur.
However, it should be borne in mind that in addition to psoriasis, the hollows on the nails are also characteristic of alopecia areata (alopecia), eczema, dermatitis and can also occur, for example, with fungal infection.
Counting the total number of punctures on all the nails will help make the correct diagnosis.
- Less than 20 - not typical for psoriasis,
- 20 to 60 - psoriasis may be suspected,
- over 60 - confirm the diagnosis of psoriasis.
White spots (leuconychia)
Leukonychia is a symptom that manifests as white spots or dots on the nails.
With leukonychia (from the Greek.Leukós- white andonychos- nail), unlike superficial pits in the symptom of a thimble, 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 the spots comes from the reflection of light from poorly localized clusters of cells.
However, some studies suggest that leukonychia is so common in healthy people that it is not a characteristic symptom of psoriasis. For example, a manicure injury can cause leukonychia.
Crumbling nails
When shallow pits (thimble symptom) and areas of deep leukonychia (white spots) merge together, the nails begin to crumble.
Typically, nail chipping 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 can completely collapse and fall out.
Red dots on the nail socket
Apparently, red dots in the area of the hole and its general redness occurs due to increased blood flow to the vessels under the nail.
In addition, 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, on the one hand, the vessels become more visible, and on the other hand, the thin nail plate exerts less pressure on the vessels below and they are more filled with blood.
Thinning of the nail plate can also cause redness of the entire nail bed.
Nail detachment (onycholysis)
Now let's consider 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 the Greek.onychos- nail andλύσις- separation) is not necessarily a sign of psoriasis and can develop, for example, as a result of a nail injury.
Initially, the loss of contact between the nail and the bed occurs in the area of hyponychia - along the outer edge of the nail plate. Then the onycholysis spreads to the crease of the nail in the form of a semicircular line. The exfoliation area turns white due to the accumulation of air under the nail.
A reddish border (scientifically erythema) along the edge of onycholysis, usually seen on the fingers, is characteristic of psoriasis and helps make the correct diagnosis.
With prolonged onycholysis, the nail bed loses its properties and the new growing nail is unlikely to be able to attach to it normally. Therefore, even with a complete renewal of the nail plate, onycholysis often persists.
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, a greenish color may appear when bacteria attach themselvesPseudomonas aeruginosa(Pseudomonas aeruginosa) and others.
Longitudinal subungual hemorrhage
Longitudinal subungual hemorrhages occur in the nail bed and appear as dark red lines 1 to 3 mm long.
Increased blood flow and edema in the area of inflammation of the nail bed lead to the rupture of 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 outer part of the nail plate.
With psoriasis, subungual hyperkeratosis (from the Greek.hyper- excessively andKeras- horn) is usually silvery white in color, but can also be yellow. And when the infection starts, it can become, for example, greenish or brown.
The higher the nail is raised above the nail bed, the higher the activity of the pathological process.
On the fingers, subungual hyperkeratosis usually manifests as loose layers under the nail plate. On the legs, these masses are tightly welded with a thickened nail.
In addition, psoriasis with lesions of the toenails is characterized by a combination of subungual hyperkeratosis with onycholysis (separation of the nail).
Oil stain symptom
The symptom of an oil stain appears under the nail plate in yellow-red (salmon) colored spots.
They appear on the nail bed closer to the crease of the nail and move to the edge of the nail as it grows.
The cause of this symptom is inflammation of the nail bed with expansion of capillaries and an accumulation of cells involved in inflammation, as well as cells with impaired division and keratinization.
Oil stains come in a variety of 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 unsightly psoriasis nails, it's not just a cosmetic issue.
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 difficulties at work.
Therefore, it is very important to make the correct diagnosis and start treatment as soon as possible, since improving the condition of the nails significantly improves the quality of life of patients with psoriasis.
Myth 4: nail psoriasis is not dangerous
In reality, this is not the case. Speaking above about the causes of this form of the disease, we have already written that
Psoriasis of the nails is an important symptom of psoriatic arthritis.
It is important to keep in mind that the external manifestations of arthritis can be completely absent. In this case, one can talk not only about the fact that the joints of the fingers and toes are affected, but also the joints of the spine and pelvic bones can be involved.
You can check your joints for arthritis using ultrasound (ultrasound) or magnetic resonance imaging (MRI).
Even if there are no obvious symptoms of arthritis, but there are manifestations of psoriasis of the nails, it is very important to make sure that all the 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, consequently, irreversible joint damage and disability.
Therefore, if the doctor did not order insurance research, citing the absence of visible signs of arthritis, you should contact the clinic yourself and undergo, for example, a chargeable ultrasound.
How to diagnose nail psoriasis
It is important to be able to recognize the many symptoms of nail psoriasis, which we have described above, because they help in making the correct diagnosis. But since the nail changes characteristic of psoriasis can also occur in other diseases, it can be difficult to make a correct diagnosis right away.
In this case, the presence of several symptoms at the same time on different nails can help in the diagnosis.
The important signs of psoriasis on the nails are:
- a symptom of a thimble: more than 20 bites on all fingernails indicate the possibility of psoriasis, and more than 60 bites confirm the diagnosis of psoriasis,
- detachment of the nail (onycholysis) with a reddish border around the edge,
- oil stains (salmon) on the nail bed.
Difficulty diagnosing nail psoriasis by a single symptom
It is especially difficult to diagnose nail psoriasis if it has only one symptom.
For example, if it manifests only onycholysis on the hands or only subungual hyperkeratosis on the arms and / or legs.
The only method of making a reliable diagnosis in isolated onycholysis (nail detachment) is probably the study of hyponychia using a special microscope - a dermatoscope.
For this, a high magnification video dermatoscope is used. Please note that the portable dermatoscope does not provide the required magnification. What is needed is a video dermatoscope with a magnification of at least 40 times. Then the dilated hair curls characteristic of psoriasis become visible.
With isolated subungual hyperkeratosis, the likelihood of psoriasis is high if the accumulation of scales under the nail is whitish-silvery in color, as well as if all the fingernails or toenails are affected.
Psoriasis or nail fungus?
About 30% of patients with psoriasis of the nails also have a fungal infection - scientifically onychomycosis.
On the outside, hyperkeratosis and onycholysis (nail separation) in psoriasis can look like manifestations of a fungal infection. Therefore, it can be difficult to make differential diagnoses, that is, to identify the true cause of changes in the nail plate.
Additionally, psoriasis and fungus can affect the same nails at the same time. Most often it occurs on the toes and is mainly characteristic of older patients.
In addition, with a fungal infection, one or both nails of the big toes are often affected. In psoriasis, as a rule, several nails are affected at once.
The following symptoms support psoriasis:
- oil stains and / or a thimble symptom on the nails,
- signs of psoriasis on the scalp and / or large skin folds,
- periodic remission and exacerbation of nail damage.
In favor of onychomycosis they say:
- longitudinal scratches on the affected nail,
- detection of fungi during the examination under the microscope of a scraping treated with potassium from an affected nail (KOH test),
- positive culture for fungi.
In general, based only on external manifestations, it is impossible to completely rule out fungal infection of the nails in patients with psoriasis.
It should also be remembered that a fungal infection can cause the Kebner phenomenon on the nail and the surrounding skin, resulting in symptoms of psoriasis. Anyway
it is helpful to go to a mycologist and test for fungi and, if necessary, initiate antifungal treatment.
Important findings and what to do
Let's summarize the important information about nail psoriasis and its symptoms.
Diagnostic features:
- Psoriasis of the nails is very common but often missed.
- Manifestations of psoriasis of the nails can be minor, so even experts often do not pay attention to them.
- In 5% of cases, nail damage may be the only symptom of incipient psoriasis.
- Manifestations of different diseases on the nails may resemble each other, which further complicates the diagnosis.
The main manifestations of psoriasis of the nails:
- a symptom of a thimble - pitting on the nail,
- white dots,
- crumbling nails
- red dots in the hole area,
- nail detachment,
- longitudinal subungual hemorrhage,
- subungual hyperkeratosis - loose lumps under the nail,
- symptom of an oil stain.
Psoriasis and fungi:
- Often nail psoriasis is accompanied by a fungal infection.
- To unequivocally exclude it, it is necessary to contact a mycologist and conduct additional research.
Psoriasis of the nails and psoriatic arthritis:
- Psoriasis of the nails is a common companion to psoriatic arthritis.
- It is important to detect pathological changes in the joints as early as possible in order to start treatment on time and to avoid complications and irreversible disabilities.
- 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 using an ultrasound or an MRI.