The skin tone on the back is uneven and patchy.

In general, uneven and patchy back skin tone may be related to factors such as ultraviolet (UV) radiation, skin aging, seborrheic dermatitis, pityriasis versicolor, vitiligo, and others. Patients are advised to follow medical guidance for symptomatic treatment. Specific analyses are as follows:

1. UV Radiation

Prolonged outdoor work and exposure to UV rays may accelerate skin aging and increase melanin activity, leading to tanning. This can result in uneven pigmentation between the back, arms, and neck. This is considered a normal physiological phenomenon, and proper sun protection is essential.

2. Skin Aging

With advancing age, the skin may become loose, dry, and lose elasticity, all of which can contribute to uneven skin tone. This is a normal physiological process and does not require specific treatment.

3. Seborrheic Dermatitis

Seborrheic dermatitis may be associated with genetic, dietary, or microbial infection factors. Patients may develop symptoms such as redness, scaling, and itching, which can also lead to the aforementioned skin discoloration. It is recommended that patients apply topical treatments such as tacrolimus ointment or pimecrolimus cream to affected areas under medical supervision.

4. Pityriasis Versicolor

Pityriasis versicolor is a fungal skin infection primarily caused by Malassezia yeast. Clinically, it typically presents as small spots on the skin that appear pale yellow or brownish, and patients may experience the symptoms described above. Treatment may include topical application of naftifine-ketoconazole cream or terbinafine hydrochloride cream as directed by a physician.

5. Vitiligo

Vitiligo is a skin depigmentation disorder primarily caused by genetic and autoimmune factors. It commonly manifests clinically as white patches or streaks on the skin, and patients may exhibit the aforementioned symptoms. Recommended treatments include topical application of fluticasone propionate cream or mometasone furoate cream under medical guidance.

In addition, uneven back skin tone may also be associated with conditions such as psoriasis or endocrine disorders. If patients experience any discomfort or unusual symptoms, they should seek timely medical evaluation at a hospital to avoid delays in diagnosis and treatment.