Uneven thumb nails can be caused by nail trauma, onychomycosis, psoriasis, lichen planus and other diseases. 1. Nail trauma: when the patient’s thumb nail is hit by external objects, collision or chemical erosion, it will lead to unevenness of the nail. 2. Ringworm of the nails: ringworm of the nails is caused by the infection of ringworm of the skin such as Trichophyton rubrum and Trichophyton mustelii. Tinea cruris can cause unevenness of thumb nails, which is mainly related to the fact that tinea cruris can release various enzymes after invading the nail plate and destroying the nail plate. In addition to uneven nails, the patient’s nails may also appear cloudy, atrophy, discoloration and other symptoms. 3. Psoriasis: The cause of psoriasis is not yet completely clear, and it may be caused by genetic factors, environmental factors and other factors. Psoriasis often causes itchy, dry skin, swollen joints and other symptoms, and also causes nails to be “thimble-like” or pitting, which is manifested as uneven thumbnails. 4. Lichen planus: lichen planus can also cause unevenness of thumb nails in some patients. The cause of lichen planus is not yet clear, and it may also lead to nail damage such as thinning of the nail plate, longitudinal ridges, surface roughness, and redness of the nail crescent. It is recommended that people with uneven thumb nails should consult a doctor for examination, and follow the doctor’s instructions for treatment after the cause of the disease is clarified.