Chapter 2 63 consequence of toxic insults to rapidly dividing matrix cells in the bulb of hair follicles. Other causes of anagen effluvium include radiation, toxins, poisoning, and alopecia areate.85 It usually occurs within days or a few weeks after exposure to the causative agents and hair re-growth can be expected in 3-6 months. Localized Hair Loss Alopecia areata: The lifetime risk for alopecia areata (AA) is 1.7% in the general population.86 AA is characterized by hair loss in circumscribe patches with rapid onset and without accompanying symptoms. A hair pull test is strongly positive in the active stage. Exclamation mark hairs are the hallmark for active AA. Multilocular form is the most common pattern of hair loss in AA (Figure 11). Extension of hair loss to the entire scalp (alopecia totalis, AT) or even the entire body (alopecia universalis, AU) can be Figure 12 Alopecia totalis Total loss of scalp hair Figure 11 Multifocal alopecia areata Multiple confluent patches of balding areas in a mosaic pattern