Hair disorders

This chapter discusses inflammatory scalp diseases and hair shedding (telogen effluvium and pattern hair loss). Inflammatory diseases of the scalp can affect all epidermal surfaces or focus upon the follicle, with relative sparing of the interfollicular skin. Eczema and psoriasis are examples of the former; other diseases, such as lichen planopilaris or discoid lupus erythematosus, are examples of the latter. Some follicular diseases, such as the family of diseases based on alopecia areata (alopecia areata (small areas of hair loss), alopecia totalis (whole scalp), and alopecia universalis (whole body)), cause barely visible follicular inflammation which results in hair loss but no scarring. Some patients present with hair shedding or change of hair pattern as their primary complaint, with no scalp disease; this is telogen effluvium. Others present with an altered pattern of scalp hair without conspicuous shedding; this is pattern hair loss.