What is the difference between flat warts and common warts?

The main differences between flat warts and common warts are as follows: 1. **Types of infecting virus**: Flat warts are primarily caused by infection with HPV types such as HPV-3, while common warts are mostly caused by HPV types such as HPV-2, 4, and 7. 2. **Lesion morphology**: Flat warts appear as flat, round or oval small elevations, with a smooth or slightly rough surface; common warts present as firm papules with a rough,明显 keratotic surface, often round or polygonal in shape. 3. **Common sites of occurrence**: Flat warts commonly occur on the face, dorsum of the hands, and forearms; common warts typically develop on the fingers, dorsum of the hands, edges of the feet, face, and forearms. 4. **Age of onset**: Flat warts are more commonly seen in adolescents, especially young females; common warts occur across a broader age range and can affect both males and females. 5. **Contagiousness**: Flat warts are relatively less contagious and generally do not spread to others; common warts may spread to other areas of the patient's own body, but similarly are not easily transmitted to others.