Viral wart

Viral warts are very common benign lesions which often occur on the hands and feet, but can occur in other areas such as the knee, and are caused by infection with human papillomavirus (HPV). They usually have a rough, hard surface, and can be single or multiple. 

Dermoscopically, the key findings with viral warts are the papillomatous features and red/black dots. 

The red dots (papillary capillaries and haemorrhages) can become black dots as the vessels elongate and thrombose. These dots are almost pathognomic of viral warts helping differentiate from other causes such as seborrheic keratoses. 

As you can see in all of the images below, the dots are present in all the dermoscopic images (despite variations in the macroscopic appearance).