Nail psoriasis is a special form of psoriasis that affects the nails on the hands and / or feet. Doctors call this type of disease psoriatic onychodystrophy (from the Greek.Onychos- nail,dys- injury,trophe- Food).
In this article, you will learn about the causes of the development of nail psoriasis, its symptoms, which do not always clearly indicate the correct diagnosis, as well as dangerous misconceptions about this form of the disease.
Note.The article contains a lot of photos that can 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 apparatus 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, we itch. Second, the aesthetic or cosmetic function of the nails is also important, especially for women.
Nails are formed from the outer layer of skin - the epidermis. The nailing apparatus 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. This is a white moon-shaped area at the base of the nail plate.
- Eponychium - a roll of nails that protects the matrix from damage from above,
- Nail bed - located under the nail plate and responsible for attaching it to the nail phalanx of the finger,
- Hyponychium - the transition zone between the nail bed and the skin of the fingertip.
Causes and mechanism of the development of nail psoriasis
Psoriasis on the nails in its course - with periodic exacerbations and remissions - resembles a vulgar form of the disease.
Nail psoriasis is believed to develop for the same reasons and in the same pattern as typical psoriasis eruptions. For these reasons, a distinction is made between external and internal factors.
The most important intrinsic factor is genetic predisposition. External causes are numerous and include injuries, poor diet, intoxicants (alcohol and tobacco), infections, and certain medications.
The standard mechanism for the development of nail psoriasis under the influence of these reasons can be briefly described as follows:
- Provoking factors such as trauma activate immune cells.
- The activated immune cells migrate to the area of the nail matrix or the nail bed.
- Immune inflammation develops in these areas.
- The division of the skin cells is greatly accelerated and their maturation is disturbed.
- There are characteristic symptoms of psoriasis on the nails.
The cause of nail psoriasis can also be seen as a result of the body's inability to adapt to adverse environmental conditions. From this point of view, the main cause of psoriasis is an evolutionarily alien habitat.
As a result, this evolutionary approach regards unhealthy diet, lack of sun and clean water, excess toxins, lack of normal physical activity, sleep disorders, and chronic stress as direct causes of illness.
Nail psoriasis and psoriatic arthritis are linked
The link between nail damage and psoriatic arthritis has long been known.
Based on observations, scientists have found that psoriatic arthritis is associated with nail damage nine out of ten.
However, the mechanism of this connection has not been fully investigated. However, the authors of several studies, for example from the Institute for Molecular Medicine in Leeds (UK), tried to explain this connection beyond the concept of immune inflammation.
The fact, in their opinion, is that the finger joint is located next to the nail and is anatomically connected to it.
Therefore, microtrauma and the Kebner phenomenon that cause primary joint inflammation - psoriatic arthritis - also cause secondary pathological changes in the next nail.
This is why psoriatic arthritis is so often associated with nail damage.
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Therefore, the symptoms of nail psoriasis often indicate 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, 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 widespread use in assessing the prevalence of this pathology is explained by accounting problems. In medical statistics, first of all, visits to the doctor by patients with vulgar form are recorded, and secondly, attention is paid to the nails. In scientific research, cases of nail psoriasis are usually studied only in addition to the main interest - psoriasis with skin lesions.
However, a number of publications say so
Up to 80-90% of patients with psoriasis vulgaris reported recurrent nail damage.
And also that psoriasis of the nails occurs in 90% of patients with psoriatic arthritis and psoriasis of the scalp.
It should be noted that adults usually suffer from this form of the disease.
According to various sources, nails are affected in about 7-37% of cases of psoriasis in children. Unfortunately, often insufficient importance is given to the manifestations of psoriasis on a child's nails. Parents or doctors believe this is a variant of the norm or a result of trauma, or they just don't notice because of the mild severity of the symptoms.
Myth 2: Identifying nail psoriasis by symptoms is easy
Indeed, not always. The thing is
The nail can only respond to various diseases with a limited number of symptoms. Therefore, the manifestations of various diseases on the nails can look the same.
Of course, nail psoriasis can be suspected if the patient has severe symptoms of psoriasis vulgaris. However, nail lesions can be minor compared to skin lesions and can be easily ignored by a doctor.
Usually, the more active the psoriasis is on the skin, the more serious the damage to the nails will be.
Initially, fingernails are affected.
And it's also important to know that nails can be the only initial manifestation of psoriasis 5% of the time. That is, the classic manifestations of psoriasis on the skin can be completely absent.
What nail psoriasis looks like depends on where the pathological changes come from - in the matrix or in the nail bed.
The cause of the symptoms - matrix or bed - should be considered when choosing a treatment. Hence, it is necessary to define it correctly.
Symptoms emanating from the nail matrix are:
- Foxglove symptom,
- white spots and spots (leukonychia),
- red dots on the hole,
- crumbling nails.
Although the cause of these symptoms is at the matrix level, as the nail grows, pathological changes occur on the nail plate.
Symptoms that are caused by the nail bed are:
- Peeling of the nail (onycholysis),
- Longitudinal bleeding,
- subungual hyperkeratosis,
- Symptom of an oil stain.
Next, we'll go into each symptom separately. Let's start with the manifestations that come from the Matrix.
Foxglove symptom
The symptom of a thimble appears on the surface of the nail plate with holes or depressions that look like depressions in a thimble.
Such defects mainly appear on the fingernails, but rarely appear on the feet. As the nail grows, the pits move from the nail fold to the edge of the nail plate.
Pits in nail psoriasis are usually deep, large, and messy. They arise from the detachment of loose cell clusters from the nail surface, in which division and cornification are impaired.
The more severe the psoriasis, the more common the foxglove symptom occurs.
However, it should be noted that in addition to psoriasis, pits on the nails are also characteristic of alopecia areata (alopecia), eczema, dermatitis and can also occur, for example, with a fungal infection.
Counting the total number of pits on all nails will help diagnose correctly.
- Less than 20 - not typical of psoriasis,
- from 20 to 60 - psoriasis can be suspected
- more than 60 - confirm the diagnosis of psoriasis.
White spots (leukonychia)
Leukonychia is a symptom that manifests itself as white spots or dots on the nails.
With leukonychia (from the Greek.Leukós- white andOnychos- Nail) In contrast to the superficial pits in the symptom of a thimble, there are cells with impaired division and cornification 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 is caused by the reflection of light from the clusters of loosely located 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 superficial pits (foxglove symptom) and deep zones of leukonychia (white spots) merge, the nails begin to crumble.
Typically, nail crumbling occurs with long-term nail psoriasis.
And the stronger the inflammation of the nail matrix, the more the nail plate is destroyed. In severe cases, the nail can collapse completely and fall out.
Red dots on the nail pan
Obviously, red spots appear in the area of the hole and its general redness due to an increase in blood flow to the vessels under the nail.
In addition, due to a violation of the structure of the nail plate itself, red dots are formed on the hole: it becomes more transparent and thinner. On the one hand, this makes the vessels more visible and, on the other hand, the thin nail plate exerts less pressure on the vessels underneath and they are more filled with blood.
Thinning of the nail plate can also lead to reddening of the entire nail bed.
Detachment of the nail (onycholysis)
Let us now consider the symptoms that are caused by 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 cornification.
Onycholysis itself (from the Greek.Onychos- nail andλύσις- Separation) is not necessarily a sign of psoriasis and can develop from a nail injury, for example.
The loss of contact between the nail and the bed occurs initially in the zone of hyponychia - along the outer edge of the nail plate. Then the onycholysis spreads in the form of a semicircular line towards the nail fold. The peeling area turns white from the build-up of air under the nail.
A reddish border (scientifically erythemic) on the edge of onycholysis, usually visible on the fingers, is characteristic of psoriasis and helps with correct diagnosis.
With prolonged onycholysis, the nail bed loses its properties and the growing new nail, most likely, will not be able to adhere to it normally. Therefore, onycholysis often persists even with complete renewal of the nail plate.
Infection can follow due to the fact that onycholysis makes it easier for bacteria and fungi to invade. This sometimes leads to discoloration of the nail. For example, a greenish color can appear when bacteria accumulatePseudomonas aeruginosa(Pseudomonas aeruginosa) and others.
Longitudinal subungual hemorrhage
Longitudinal subungual bleeding occurs in the nail bed and appears as dark red lines 1 to 3 mm in length.
Increased blood flow and edema in the area of inflammation of the nail bed lead to rupture of the capillaries, which is expressed in the form of such bleeding.
Due to the peculiarities of the blood supply, most bleeding occurs closer to the free edge of the nail - in the zone of hyponychia.
Subungual hyperkeratosis
Subungual hyperkeratosis is a collection of dead cells under the outer part of the nail plate.
With psoriasis, subungual hyperkeratosis (from the Greek.hyper- excessive andKeras- Horn) is usually silver-white in color, but it can also be yellow. And when the infection joins, it can turn greenish or brown, for example.
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. These masses are firmly soldered to the legs with a thickened nail.
Psoriasis with toenail lesions is also characterized by a combination of subungual hyperkeratosis with onycholysis (nail separation).
Oil stain symptom
The symptom of an oil stain appears under the nail plate in yellow-red (salmon) spots.
They arise on the nail bed closer to the nail fold and move towards the edge of the nail as they grow.
The cause of this symptom is inflammation of the nail bed with expansion of the capillaries and an accumulation of cells involved in the inflammation, as well as cells with impaired division and cornification.
Oil stains come in different shapes and sizes. They are located both in the center of the nail and on the edge next to the onycholysis zone.
Myth 3: Nail psoriasis is only a cosmetic problem.
In fact, this is not true. Although over 90% of patients report unsightly psoriatic nails, it's 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 with 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 early as possible, because improving the condition of the nails will greatly improve the quality of life of patients with psoriasis.
Myth 4: Nail psoriasis is not dangerous
In reality this is not the case. If we talk about the causes of this form of the disease above, we have already written that
Nail psoriasis is a major symptom of psoriatic arthritis.
It is important to remember that the external manifestations of arthritis may be completely absent. In this case, we 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.
You can use ultrasound (ultrasound) or magnetic resonance imaging (MRI) to check your joints for arthritis.
While there are no obvious symptoms of arthritis but manifestations of nail psoriasis, it is very important to make sure that all joints are in good condition.
And then regularly monitor the condition of the joints. Otherwise, psoriatic arthritis is easy to miss! Late diagnosis leads to late treatment and thus irreversible joint damage and disability.
Therefore, if the doctor has not commissioned insurance research and there are no visible signs of arthritis, then you need to contact the clinic yourself and, for example, undergo a paid ultrasound scan.
How to diagnose nail psoriasis
It is important to be able to identify the many symptoms of nail psoriasis that we described above as they will help in making the correct diagnosis. Because nail changes that are characteristic of psoriasis can also occur in other diseases, it can be difficult to make a correct diagnosis right away.
In this case, the simultaneous presence of multiple symptoms on different nails can help in the diagnosis.
Important signs of psoriasis on the nails are:
- a symptom of a thimble: more than 20 pits on all the nails of the hands indicate the possibility of psoriasis, and more than 60 pits confirm the diagnosis of psoriasis.
- Detachment of the nail (onycholysis) with a reddish border around the edge,
- Oil stains (salmon stains) on the nail bed.
Difficulty diagnosing nail psoriasis from a single symptom
It is especially difficult to diagnose nail psoriasis when it has only one symptom.
For example, if it manifests itself only in onycholysis of the hands or only in subungual hyperkeratosis of the arms and / or legs.
Probably the only method of reliable diagnosis in isolated onycholysis (nail detachment) is to examine the hyponychia with a special microscope - a dermatoscope.
A video dermatoscope with high magnification is used for this. Please note that the handheld dermatoscope does not offer the required magnification. What is needed is a video dermatoscope with a magnification of at least 40 times. Then the enlarged capillary loops characteristic of psoriasis become visible.
With isolated subungual hyperkeratosis, the likelihood of psoriasis is high if the scales under the nail build up whitish-silver and all the nails on the hands or feet are affected.
Psoriasis or nail fungus?
About 30% of patients with nail psoriasis also have a fungal infection - scientifically, onychomycosis.
Outwardly, hyperkeratosis and onycholysis (separation of the nail) in psoriasis can resemble the manifestations of a fungal infection. Therefore, it can be difficult to perform differential diagnosis, that is, to identify the real cause of changes in the nail plate.
In addition, both psoriasis and fungus can attack the same nails at the same time. Most often it occurs on the toes and is especially characteristic of the elderly.
A fungal infection often affects one or both nails on the big toes. Psoriasis usually affects several nails at the same time.
The following symptoms suggest psoriasis:
- Oil stains and / or a symptom of a thimble on fingernails,
- Signs of psoriasis on the scalp and / or large folds of skin,
- periodic remission and exacerbation of nail damage.
For onychomycosis they say:
- Longitudinal stripes on the affected nail,
- Detection of fungus during examination of a potassium hydroxide-treated scratch from an affected nail under a microscope (KOH test);
- positive culture for mushrooms.
In general, due to external manifestations, it is impossible to completely rule out fungal infection of the nails in patients with psoriasis.
It should also be noted that a fungal infection can cause the Kebner phenomenon on the nail and surrounding skin, leading to psoriasis symptoms. So anyway
It is useful to see a mycologist for a fungal test and, if found, initiate antifungal therapy.
Key takeaways and what to do
Let's summarize important information about nail psoriasis and its symptoms.
Diagnostic functions:
- Nail psoriasis is very common but is often overlooked.
- Manifestations of nail psoriasis can be minor, so often even experts do not pay attention to them.
- In 5% of cases, nail damage can be the only symptom of the onset of psoriasis.
- The manifestations of various diseases on the nails may look the same, which makes the diagnosis even more difficult.
The main manifestations of nail psoriasis:
- a symptom of a thimble - pits on the nail,
- White dots,
- crumbling nails
- red dots in the hole area,
- Detachment of the nail,
- subungual longitudinal hemorrhage,
- subungual hyperkeratosis - loose clusters under the nail,
- Symptom of an oil stain.
Psoriasis and fungus:
- Nail psoriasis is often associated with a fungal infection.
- To clearly rule this out, a mycologist must be contacted and additional examinations performed.
Nail psoriasis and psoriatic arthritis:
- Nail psoriasis is a common companion to psoriatic arthritis.
- It is important to identify pathological changes in the joints as early as possible in order to start treatment on time and avoid irreversible complications and disabilities.
- Even if there are no external symptoms of arthritis, but nail psoriasis is detected, an examination of the joints using ultrasound or MRI is required.