Pigmented Casts in Alopecia: A 2014 Study

In the 2014 study "Pigmented Casts," researchers analyzed 308 scalp biopsies from patients with different types of alopecia to evaluate the presence and morphology of pigmented casts. They found pigmented casts in 72% of alopecia areata cases, 100% of trichotillomania and dissecting cellulitis cases, 14% of central centrifugal cicatricial alopecia cases, and in one case of friction alopecia. The study concluded that pigmented casts are not specific to any single diagnosis but can be indicative of alopecia areata when found in miniaturized/vellus hairs. The morphology of pigmented casts was notably different in trichotillomania, with a twisted, linear, and "button"-like appearance. Horizontal sections of scalp biopsies were useful for assessing pigmented casts, which, along with other follicular findings, may assist in the diagnosis of hair disorders. The document also explained that pigmented casts form through various mechanisms in different hair disorders, often due to hair breakage or follicular damage, and emphasized the importance of recognizing these features to avoid misdiagnosis between alopecia areata and trichotillomania.