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INTRODUCTION TO CHAPTER
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The hair follicle is a complex structure which produces a hair fiber consisting of a cortex, medulla and cuticle (Figures 30-1, 30-2). Hair follicles demonstrate the unusual ability to completely regenerate themselves. Hair grows, falls out, and then regrows. In the normal human scalp, up to 90% of hair follicles are in the growth phase called anagen, 1% in the transition phase catagen and up to 10% in telogen or the loss phase. The anagen phase lasts approximately 3 years, catagen 2–3 weeks and telogen 3 months.1
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Hair disorders are broadly grouped into the following categories:
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Hair loss is common and can occur with a variety of medical conditions. The workup of this chief complaint starts with a thorough history and physical examination as outlined in Tables 30-1 and 30-2, respectively.
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The nonscarring hair disorders associated with abnormalities in the hair cycle include three very common hair disorders:
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These nonscarring hair diseases are associated with changes to the anagen, or growing stage of the hair cycle.
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The scarring alopecias are ...