Trichoscopy of Alopecia areata: What do the features mean?

Dermatoscopic Features of Alopecia Areata. 

This chart is a helpful guide for those who care for patients with alopecia areata. 
Patients with advanced alopecia areata have a higher chance of having black dots, short vellus hairs and yellow dots. Those with active disease often show black dots, short vellus hairs, tapered hairs (exclamation mark) and broken hairs. One can see here that yellow dots and short vellus hairs are the most sensitive finding - which simply means they are the features most likely to be seen.