Etiology and Clinical Presentation
Patients afflicted with diffuse alopecia typically complain of hair loss all over the scalp not just in the areas usually seen in androgenetic alopecia. However, the differential diagnosis of diffuse alopecia versus androgenetic alopecia, particularly in females, can be difficult because of the similar presentation, and biopsy and histological assessment may be required to confirm the diagnosis. The course of the diffuse alopecia can be continuous or episodic. Diffuse alopecia may present as telogen or anagen effluvium and can be caused by drug and chemical exposure, thyroid disorders, nutritional influences, and psychological stress.
Telogen effluvium is characterized by abrupt, diffuse hair loss. Common causes are childbirth, febrile illnesses, surgery, psychological stress, crash diets, and drug therapy (38). The excessive shedding usually begins 3 to 4 months after the inciting event (39). Anagen effluvium is characterized by widespread or circumscribed loss of anagen hairs from growing follicles. Alopecia due to anagen effluvium is quite obvious because 90% of the hair follicles are in anagen (growing) phase. In contrast with telogen effluvium, loss of anagen hair begins within days to a few weeks after the inciting event. Common causes of anagen |
effluvium are radiation, toxic drugs, environmental and occupational exposure to hazardous chemicals, and loose anagen syndrome (39). Drug- and chemical- -a induced hair loss is usually confined to the scalp and is most often diffuse, but it can be patterned or localized. It can also manifest itself as a telogen or anagen «
effluvium. Hypothyroidism is directly correlated with diffuse alopecia, whereas
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