Alopecia areata – Causes and Associated Conditions
Alopecia areata is genetically linked to several other autoimmune conditions, particularly atopy (asthma, eczema and allergic rhinitis), thyroid disease, vitiligo, and less commonly, pernicious anemia and lupus erythematosus. These conditions do not cause the hair loss, they are just genetically linked and can be found in the patient with alopecia areata or in close relatives. The only one of these associated conditions which appears to exert some effect on the course of the alopecia is atopy. Patients with alopecia areata and atopy can have worsening of their alopecia seasonally with worsening of their atopic diseases.
The cause of alopecia areata is unknown. It is postulated to have an autoimmune pathogenesis because of its relationship to other autoimmune conditions and the presence of lymphocytes around follicular bulbs on biopsies of early active disease. The condition results in marked miniaturization of affected hair follicles. Hair shafts often break off at the scalp causing black dots and a rough feel in active areas. Patients often mistakenly think this is evidence of regrowth when it actually signals active hair loss. Exclamation point hairs, pathognomonic of alopecia areata, are hairs that taper proximally (towards the scalp). They are often found at the periphery of active areas of alopecia.