Can you diagnose hair loss (Non-scarring alopecia)

Abstract

Alopecias are broadly divided into scarring and non-scarring forms. From a clinical perspective, follicular ostia are preserved in non-scarring alopecia, while histopathologically, there is preservation of follicular unit architecture, presence of intact sebaceous glands, and normal to near normal numbers of hair follicles. In chronic, longstanding non-scarring alopecias, follicular drop out may eventually ensue, resulting in absolute decrease in hair follicle numbers. Choice of biopsy site contributes significantly to accurate histopathological diagnosis. Areas of active hair loss are preferred. At the National Skin Centre, Singapore, it is routine practice to take two 4 mm punch biopsy specimens in suspected non-scarring alopecia; one specimen is sectioned vertically while the other is sectioned transversely. In non-scarring alopecias, transverse sections render very useful information. It allows for assessment of follicular unit integrity, hair counts, anagen:telogen and terminal:-vellus hair ratios. It also allows for visualisation of all hair follicles within the biopsy specimen at a glance. In this talk, some common forms of non-scarring alopecias (e.g., androgenetic alopecia, alopecia areata, traction alopecia, trichotillomania, etc.) will be discussed, with emphasis on interpreting transverse sections.