Is it onychomycosis or psoriasis? Don't be confused

Author: Tang Qin, Deputy Secretary-General of the Science Popularization Expert Committee of the Chinese Medical Association

Reviewer: Zhang Shuyuan, Chief Physician, Beijing Huayi Integrated Traditional Chinese and Western Medicine Dermatology Hospital

Xiao Wang found that his nails had changed color and were growing thicker and thicker. He suspected that he had onychomycosis, but after going to the hospital for treatment, he found that he did not have onychomycosis but nail damage caused by psoriasis.

Figure 1 Copyright image, no permission to reprint

1. Psoriasis and Psoriatic Nail Lesions

Psoriasis is an immune-mediated disease caused by multiple factors, the main causes of which are genetic, environmental and immune factors.

Psoriasis can occur in any age group and there is no obvious gender difference. Clinically, most patients will experience relapse or worsening of the disease in winter. The more typical symptoms are localized or widespread scaly erythema or plaques.

Skin lesions caused by psoriasis generally appear all over the patient's body, and the nails are the most easily affected area in most psoriasis patients, leading to the formation of psoriatic nail lesions [1].

2. Easily confused psoriasis nail lesions and onychomycosis

Normal nails are mostly translucent, with a relatively smooth and neat surface, appear pink, and have a certain curvature.

But psoriasis can cause nail abnormalities, with tiny pinprick-like depressions on the nails, similar to thimbles, and discoloration, thickening, or separation of the nail plate from the nail bed.

The main symptoms of onychomycosis are also nail deformation, thickening, turbidity, separation, discoloration, loss of luster and uneven surface of the nail plate. In severe cases, the nail plate is completely detached from the base. Therefore, many people cannot easily distinguish between the two.

Some psoriasis patients even treat the nail lesions caused by psoriasis as onychomycosis. This not only fails to cure the nail lesions, but makes their condition worse.

Therefore, it is very important to understand the difference between psoriatic nail lesions and onychomycosis.

Figure 2 Copyright image, no permission to reprint

3. The obvious difference between psoriasis nail lesions and onychomycosis

Psoriatic nail lesions mainly occur in patients with psoriasis and do not appear only in the form of nail lesions; while the lesions caused by onychomycosis are mainly concentrated on the patient's nails, and one or more nails may be affected.

In addition, there are three differences between psoriasis and onychomycosis:

1. Different sites of disease

When psoriasis patients develop nail lesions, psoriasis-related symptoms usually appear in other parts of the body. Nail lesions caused by psoriasis usually appear on both hands at the same time, and the number of affected nails is not equal, and the severity of the disease is also different. However, onychomycosis and psoriasis nail lesions are different. The main concentrated area of ​​the lesions is the nails, usually starting with 1 to 2 nails, starting from the edge of the nail. In severe cases, all nails may be affected.

2. Different clinical manifestations

When psoriasis patients develop nail lesions, some small depressions like those pricked by needles will first appear on the nails, and the nail plate may also change color, thicken, or separate from the nail bed. Onychomycosis patients will have longitudinal white stripes on the nail plate. These stripes will pass through the arc shadow of the patient's nail plate, and then the white color will disappear, turning into dark stripes with longitudinal ridges. The nail plate will become brittle and very easy to crack. The stripes may appear as "V"-shaped notches at the free edge of the nail, sometimes accompanied by thickening under the distal nail.

3. Different infectiousness

Psoriasis patients do not need to worry about the infectiousness issue as the fungal test results are negative; however, onychomycosis is caused by fungal infection and is somewhat contagious.

Knowing the difference between psoriatic nail lesions and onychomycosis, we should pay attention to distinguishing the two in our daily lives, and not treat psoriatic nail lesions as onychomycosis. If the nails are abnormal, do not blindly take medicine on your own, but go to the hospital for diagnosis and treatment in time to determine whether it is psoriatic nail lesions or onychomycosis, and use symptomatic treatment to reduce the damage.

References

[1] Chinese Medical Association, Chinese Medical Association Journal, Chinese Society of Dermatology and Venereology, et al. Guidelines for diagnosis and treatment of psoriasis at the primary level (2022)[J]. Chinese Journal of General Practitioners, 2022, 21(8):705-714.