Psoriatic alopecia - fact or fiction? A clinicohistopathologic reappraisal

The incidence of psoriatic alopecia in psoriatic patients is underwhelming, given the prevalence of psoriasis in the North American population. Recently, a 60-year-old Albanian female, lacking a significant medical history for psoriasis, presented to our clinic with a 1-year history of "dandruff" associated with itch, hair thinning, and histopathologic evidence consistent with prior reports of "psoriatic alopecia."

The absence of preceding or concomitant psoriasis suggests that the patient's alopecia is an antecedent manifestation of psoriasis, thus prompting this retrospective study to ascertain better the relationship between alopecia and psoriasis.

We performed a retrospective review of 33 scalp biopsies on 31 patients having histopathologic diagnosis of psoriasis belonging to 31 patients seen between 2007 and 2010.

Alopecia was a presenting feature in 48% of cases with definitive clinical and/or histopathologic diagnosis of psoriasis (scale crust with neutrophils, psoriasiform epidermal hyperplasia, and hypogranulosis). The most common follicular-related changes were infundibular dilatation (87%) followed by perifollicular fibrosis (77%), perifollicular lymphocytic inflammation (68%), thinning of the follicular infundibulum (55%), and fibrous tracts (28%). Of interest, sebaceous glands were absent in 60% and atrophic in 25% of cases.

While a major limitation of this study is that it is a retrospective one, given that these changes are common to varying degrees in all lymphocytic scarring alopecias, we posit that psoriatic alopecia likely represents a secondary clinical change to a primary process and is not a unique histopathologic entity. A prospective study with a control group that includes lymphocytic scarring alopecias from non-psoriatic patients is required to support our findings.