What causes white patches on the faces of adolescents?

The main causes of white patches appearing on the faces of adolescents include: 1. **Vitiligo**: This is a common skin condition caused by genetic and autoimmune factors. It presents as patches of varying sizes and irregular shapes on the face, with clear boundaries, smooth surfaces, and no scaling. 2. **Pityriasis alba**: Also known as simple pityriasis, this condition commonly affects adolescents and is associated with diet, sun exposure, and local irritation. It presents initially as light red macules on the face, which later shed gradually, forming white hypopigmented patches. 3. **Tinea versicolor**: Caused by Malassezia infection, it presents as white patches or round macules on the face. 4. **Skin injuries**: Localized pigment loss may occur following trauma, resulting in white patches. 5. **Sun exposure**: Prolonged exposure to sunlight may damage melanocytes, leading to the formation of white patches. 6. **Malnutrition**: Deficiencies in vitamins or trace elements may also affect skin pigment metabolism and result in white patches.