Acquired progressive kinking of the hair in an elderly woman: a case report.

Acquired progressive kinking of the hair (APK) is a rare disorder that presents at any age and is infrequently presented in the literature. This diagnosis has been used to describe similar hair changes, though there are significant differences in presentation, population, and individual clinical features. Histologic analysis of hair shafts aids in diagnosis owing to commonly reported features such as irregular twisting, bending, and grooving of hair shafts with polygonal shapes on cross-section. We present a case with classic histologic features in an unusual patient to highlight this rare condition. Additional cases and studies are necessary to evaluate etiology, differentiate subsets of APK, and develop both treatment and prevention strategies.