Contributor: Gordon K. Klintworth
Alopecia circumscripta (alopecia areata, pelade) is a patchy immunologically mediated idiopathic sharply demarcated type of alopecia that usually involves the beard or scalp. The disorder may be associated with Hashimoto disease, vitiligo, pernicious anemia, and Addison disease. The hair follicles are not initially lost and the hair loss is often reversible. Prior to the hair loss affected individuals often experience dysesthesia in the region of the incipient alopecia. The disorder is not accompanied by a scaling or erythema of the adjacent epidermis, but a microscopic inflammatory cell infiltrate consisting of a mixture of CD4 and CD8 T-cells. Immunoglobulin deposits are not present. A chronic variety forms a continuous band around the lower edge of the temporal and occipital scalp (ophiasis).