Онихомикоз: клинические формы и диагностика согласно последним гайдлайнам

According to the latest data onychomycosis in 15%-40% of cases of treatment for nail diseases (data from the British Association of Dermatologists), this is an average of one in four patients. Every fourth patient who did visit a dermatologist.

When treating this disease, dermatologists most often face such a problem as frequent relapses, which occur in 40%-70% of cases.

What is the reason for such a high incidence and a huge percentage of relapses? After all, 40% -70% is, on average, every second patient who returns again with this problem, read on estet-portal.com.

Definition and general information

Onychomycosis – an infectious lesion of the nail plates and, in some cases, the nail bed of a fungal nature. The most common causative agents of which are dermatophyte fungi, but there may be a number of other pathogens, such as Candida and moulds.

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Fungal infection of the nails can have a significant impact on the quality of life of patients. The problems associated with this disease are: discomfort, difficulty in wearing shoes, pain when walking, aesthetic defects in the form of deformed nails and an unpleasant odor, which lead to a decrease in the patient's self-esteem and affect the quality of life.

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Etiological factors of onychomycosis

Risk Factors:

  • old age
  • peripheral vascular disease
  • trauma and hyperhidrosis

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Fungal nail infections are more common in the following categories of patients:

- who wear tight-fitting shoes (blood circulation is disturbed, foot hyperhidrosis appears, nail plates are injured)

- with a genetic predisposition. (Studies suggest that there are familial patterns associated with T. rubrum infection.)

- with associated nail diseases such as psoriasis

- with immunosuppressive conditions (for example, with concomitant diabetes mellitus, obliterating vascular diseases or HIV infection)

- patients who take immunosuppressants

Classification and clinical manifestations

There are five main clinical models:

  1. Distal and lateral subungual onychomycosis

The most common manifestation of a fungal nail infection. Toenails are more commonly affected than those of the hands. The fungus invades the nail and nail bed, penetrating the distal or lateral margins.

Think about it: every second patient with fungal nail disease will return to you with a relapse after some time.

The affected nail becomes thickened and discolored with varying degrees of onycholysis (separation of the nail plate from the nail bed), although the nail plate is not initially affected. The infection may be limited to one side of the nail or spread to the entire nail bed. Over time, the nail plate becomes loose and may break.

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T. rubrum is the most common pathogen. Since distal and lateral subungual onychomycosis bears a marked resemblance to non-fungal nail disease, it is important to obtain a nail sample for microbiological examination so that the causative agent can be identified.

2. Superficial white onychomycosis

Infection usually begins on the superficial layer of the nail plate and spreads to deeper layers. White spots appear on the surface of the nail, especially on the legs, which can peel off. They gradually spread until the entire nail plate is involved.

3. Proximal subungual onychomycosis

The least common manifestation of dermatophyte nail infection in the general population, it is common in people with AIDS. The infection often spreads rapidly from the proximal to the distal end of the nail, resulting in a pronounced discoloration of the plate without obvious thickening.

4. Endonyx-onychomycosis

Instead of penetrating into the nail bed over the edge of the nail plate, the fungus immediately penetrates into the thickness of the nail plate. In the absence of onycholysis and subungual hyperkeratosis, the nail plate becomes white. The most common pathogens are T. soudanense and T. violaceum.

5. Total dystrophic onychomycosis (TDO)

Any of the listed types of fungal infection can eventually turn into TAR when the nail plate is almost completely destroyed. Primary TAR is rare and is usually caused by Candida species, which usually affect immunocompromised patients.

Clinical differences and differential diagnosis

•    Clinical signs of dermatophytosis are often difficult to distinguish from a number of other infectious causes of nail damage, such as Candida, mold, or bacterial infection. Unlike dermatophytosis, candidiasis of the nails usually begins in the proximal plate of the nail, and is also present in the nail fold (paronychia).

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Bacterial infection, especially when caused by Pseudomonas aeruginosa, tends to result in green or black discoloration of the nails. Sometimes a bacterial infection may coexist with a fungal infection and may require combined treatment.

•    Other less common nail dystrophic conditions that mimic onychomycosis are Darier's disease and lichen planus, as well as ichthyotic conditions such as keratosis and ichthyosis. Often, yellow nail syndrome is misidentified as a fungal infection. Light green-yellowish pigmentation of the nail plate, hardness, and increased longitudinal striation are the key clinical features of this nail disease.

•    Repeated trauma to the nail plate can also lead to nail deformity. The nail bed will appear normal if the symptoms are due to trauma rather than onychomycosis, with a characteristic pattern of intact longitudinal epidermal ridges extending to the socket.

"Improper sampling of material for research may lead to the fact that therapy will not be effective"

The clinical characteristics of dystrophic nails should alert the physician to a possible fungal infection.

Laboratory confirmation of the diagnosis must be obtained prior to treatment. This is important for several reasons:

• exclude non-fungal nail diseases;

• detect mixed infections;

• diagnose patients with less sensitive forms of dermatophytosis, such as T. rubrum toenail infections.

See also: Fungal infection of the nasal cavity

Good nail tissue samples are sometimes difficult to obtain, but critical to maximum laboratory diagnosis. The material should be taken from any discolored, dystrophic or brittle parts of the nail. It must be taken exactly from the affected area of ​​the nail.

Nail drills and scalpels may be used for sampling and should be sterilized between each patient. When the damage to the nail is superficial, you can take a scraping from the nail using a special curette.

Laboratory diagnosis of onychomycosis consists of culture and microscopy, the results of which will be available in about 2-6 weeks.

As we can see, the clinical picture of this disease is very variable, the diagnosis can be made only after laboratory confirmation. However, incorrect sampling of material for research can lead to the fact that the therapy will not be effective and all your efforts will be wasted.

In the next article, we will review the latest recommendations of the British Dermatological Association for the treatment of onychomycosis.

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