What Are the Causes of White Patches Appearing on the Skin?

The appearance of white patches on the body may be caused by vitiligo, pityriasis versicolor, pityriasis alba, amelanotic nevus, idiopathic guttate hypomelanosis, and other reasons. Here are the details:

1. Vitiligo

Vitiligo is a common acquired skin pigmentation disorder. The white patches on the affected area are smooth and flaky, with a pale white or milky white color. The edge pigmentation is increased compared to normal skin, and the hair within the patches may be normal or white. The lesions are prone to occur in areas exposed to sunlight and friction, and the lesions are often symmetrically distributed. The white patches are also often distributed in a zonal arrangement along nerve segments. In addition to skin damage, the lips, labia, glans penis, and inner mucosa of the foreskin are also often affected. Most patients have no conscious symptoms, but a few may experience local itching at or before the onset of the disease. There is no significant gender difference in the incidence, and it can occur in all age groups, but it is more common in adolescents.

2. Pityriasis Versicolor

Also known as tinea versicolor, pityriasis versicolor is a chronic condition that usually has no conscious symptoms. The characteristic lesions are scattered or fused hypopigmented or hyperpigmented macules with fine scaling, commonly affecting the chest, back, upper arms, and axillae, and sometimes also the face. Initial lesions are round, punctate macules around hair follicles, which gradually increase to the size of a fingernail, with clear edges. Neighboring lesions may fuse into irregular large patches, with new macules appearing around them. The surface is covered with a small amount of easily removable, fine scaling, ranging in color from gray, brown to yellowish-brown, sometimes with multiple colors coexisting, resembling a flower pattern. Older lesions may appear as light-colored patches.

3. Pityriasis Alba

Typical skin lesions of pityriasis alba are faint red, round or oval patches with blurred edges, measuring 0.5 to 2.0 cm or larger in diameter. After several weeks, the pale red patches gradually turn into pale white patches, covered with a small amount of fine scaling. The number of lesions varies, and they are mainly distributed on the face, occasionally also seen on other parts of the body. There are no conscious symptoms, or there may be itching or burning sensations. The duration of the disease varies, worsening in summer but can resolve naturally.

4. Amelanotic Nevus

Also known as achromic nevus, it is a rare, congenital, localized white patch. It develops at birth or shortly after birth, and the white patch may expand proportionally with body growth. Pigment will not regenerate in the depigmented area, so it cannot disappear naturally. Skin lesions are common on the trunk, lower abdomen, proximal extremities, and can also affect the face and neck. If the lesion occurs in the trigeminal nerve area, it may be accompanied by neurological symptoms and epilepsy. Currently, there is no effective drug treatment for this condition. If necessary for cosmetic purposes, the lesions on exposed areas can be covered. After adulthood, autologous epidermal grafting can be performed.

5. Idiopathic Guttate Hypomelanosis

Also known as idiopathic guttate hypomelanosis, this condition is mostly distributed on exposed areas such as the limbs, face, and trunk. The symptoms are milky white patches with a diameter of about 2 to 6 mm, sometimes larger, with irregular shapes, round or polygonal. The prevalence rate increases with age. As this condition has little impact on appearance, no treatment is required. To prevent this condition, it is advisable to avoid sun exposure.