**14. Androgenetic alopecia**

Androgenic alopecia is the most common type of hair loss. Clinically, it is a patterned alopecia, in that it is characterized by bitemporal recession and vertex balding in men, and in women (female pattern hair loss) by diffuse hair thinning of the crown with an intact frontal hairline. Histopathologically, the use of transverse sections is the most valuable method to reach a diagnosis [16], as all the hair follicles can be visualized.

The terminal (T) to vellus (v) ratio is T: V= less than 4:14. Normal scalp ratio is T: V= 7:1). A ratio of T: V= 3: 1 or less is considered to be diagnostic [16], [17].
