Characteristics of the early stage of flat warts

The characteristics of the early stage of flat warts mainly include: 1. **Lesion morphology**: Early-stage warts are usually small, presenting as smooth-surfaced papules with clear boundaries, often round, oval, or polygonal in shape, and relatively firm in texture. 2. **Color**: The color of early-stage warts is often similar to normal skin tone or light brown, closely matching the surrounding skin color, making them difficult to notice. 3. **Size**: The size of the warts is approximately that of a grain of rice to a green pea, and they may gradually enlarge as the condition progresses. 4. **Symptoms**: In the early stage, flat warts generally cause no subjective symptoms, although a few patients may experience mild itching. Scratching may lead to autoinoculation, resulting in a linear, bead-like arrangement along the scratch marks. 5. **Common locations**: Flat warts commonly occur on exposed areas such as the face, dorsum of the hands, and forearms, and are especially prevalent among adolescents. 6. **Cause**: Flat warts are caused by infection with the human papillomavirus (HPV). Transmission mainly occurs through direct contact, with trauma and impaired skin barrier function being the primary contributing factors for infection.