Differential patterns of elastic fibers in scarring and non-scarring alopecias.
Elastic fiber stain (acid alcoholic orcein) reveals diagnostically significant differences between several types of alopecia of the scalp. A short outline of elastic fiber distribution on the normal hair follicle emphasizes the elastic coat of the follicular isthmus, the sparsity of elastic fibers on the cyclic lower portion of the hair root, and the presence in the neck of the dermal papilla of an elastin-like body which is formed anew with each hair cycle. This body provides a marker of the gradual shortening of successive anagen hairs in male pattern alopecia. Patterns of elastic fibers in the perifollicular and interfollicular dermis are helpful in differentiating idiopathic pseudopelade of Brocq from pseudopeladic states secondary to lupus erythematosus and other disease processes. Within the idiopathic group, the development of elastic fibres on the lower cyclic portion of the hair root identifies a sub-group that may have a different, non-inflammatory pathogenesis and is provisionally designated as fibrosing alopecia.