[Medical Q&A] What is the difference between psoriasis and onychomycosis?

Planner: Chinese Medical Association

Reviewer: Sheng Yujun, deputy chief physician of China-Japan Friendship Hospital

Both psoriasis and onychomycosis may cause onycholysis, which can be distinguished mainly from the following points.

(1) Disease incidence

Psoriatic nails: Multiple nails may be affected at the same time, with 3 out of 5 toenails being affected.

Onychomycosis (onychomycosis): It starts from a single nail and gradually spreads to other nails, with 1 in 5 toenails being affected.

(2) Size and shape of nail pits

Psoriatic nails: Uniform and consistent, the dots on one nail are of the same size and evenly distributed.

Onychomycosis (onychomycosis): Irregular, the size and shape of the spots on a nail are inconsistent.

(3) Characteristics of diseased nails

Psoriatic nails: The nail plate is not obviously opaque, and yellow-brown patches appear.

Onychomycosis (onychomycosis): The nails will change color, become dull, thicken or thin, become broken and incomplete, and the entire nail will turn yellow-brown.

(4) Fungal microscopy

Psoriasis A: Negative.

Onychomycosis (onychomycosis): hyphae or spores are detected.