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Comment différencier une mycose d'un psoriasis aux ongles ?

Fungal Infection or Nail Psoriasis?

Psoriasis is a chronic disease that affects the skin, characterized by the formation of red patches and thickening of the epidermis in certain areas of the body. When it appears on the nails, it is referred to as nail psoriasis or psoriatic nails. It is often mistaken for nail fungus due to their many similarities. However, nail psoriasis and onychomycosis are two distinctly different conditions. Let's explore their main differences in this article.

Summary
Published September 29, 2023, updated on February 20, 2024, by Manon, Scientific Editor — 4 min read

Nail Psoriasis: An Autoimmune Disease.

nail psoriasis , this form of psoriasis is localized to the nails. It primarily affects the fingernails. It is estimated that 35 to 50% of patients suffering from psoriasis have lesions localized to the nails. This disease can occur at any age and manifests in various ways. It is caused by the failure of the immune system due to accelerated renewal of keratinocytes. When psoriasis affects the nail matrix, it causes the appearance of pitted holes on the surface of the affected area. It can also manifest on the nail bed. In this case, the symptoms are:

  • The thickening of the nails or the skin under the nails, a condition known as hyperkeratosis;

  • The loss of nail transparency with the appearance of pinkish spots;

  • Of a nail detachment, onycholysis, and deformation of the nail.

Even though psoriasis is not contagious, it must be treated, as its symptoms can impair the patient's quality of life. The appropriate treatments for nail psoriasis depend on its severity. To alleviate the symptoms of this disease, one can opt for:

  • Local remedies to be applied directly to the affected area;

  • General treatments to be taken orally or by injection;

  • The use of biotherapies.

Nail Fungus: A Fungal Infection.

Nail fungus, also known as onychomycosis, is an infection caused by fungi. These fungi most commonly attack the toenails, but they can also develop on the fingernails.

The fungi that cause mycosis are composed of several microorganisms capable of multiplying rapidly. Dermatophytes are responsible for the majority of onychomycosis cases. Particularly the Trichophyton rubrum is the dermatophyte most commonly associated with onychomycosis. It can also cause other fungal skin infections. The fungi responsible for nail mycosis begin their parasitism by first invading the spaces between the toes, called interdigital spaces, then progress towards the sole of the foot and finally reach the nail itself.

There are also conditions that promote their proliferation such as humidity, the presence of lesions, or perspiration. Nail fungus should be addressed at the first signs of infection to prevent it from worsening over time. Moreover, this condition is contagious. The management of onychomycosis involves applying an antifungal product daily to the area where it develops.

Psoriasis and nail fungus: what are the differences?

Nail psoriasis is relatively easy to diagnose as it is often associated with skin plaques. However, in the absence of these, it can be mistaken for nail fungus since these conditions share many similarities. Indeed, both diseases alter the appearance of the nail. Nevertheless, the fungus is distinguished from psoriasis by making the nail brittle and yellow. Psoriasis, on the other hand, causes the appearance of small holes on the nail surface or pinkish spots. Often, the doctor will conduct a mycological sampling to confirm the diagnosis. Moreover, it is possible to be affected by both nail fungus and nail psoriasis. Indeed, sensitized nails are more susceptible to fungal attacks.

Sources

DUHARD-BROHAN E. Psoriasis unguéal. Annales de Dermatologie et de Vénéréologie (1999).

COGREL O. Psoriasis de l'ongle (Psoriasis unguéal). Association France Psoriasis (2022).

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