A:A curly hair grows from a sharply curved hair root. When shaved, the hair is left with a sharp point. As this hair grows, the sharp tip curves back and pierces the skin.
B:The sharpened hair penetrates the skin.
C and D:When hairs are cut too closely, they can penetrate the side of the hair root. Both types of follicular reentry cause a foreign body-like reaction (papule).
CrutchfieldCE III. Patient handout: Treatment of razor bumps, 1996. Available at: http://www.crutchfielddermatology.com/treatments/pseudofolliculitisbarbae/1.htm.
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