RESUMO
BACKGROUND: Psoriasis is a common, chronic skin eruption characterized by abnormal hyperproliferation of the epidermis. When assessing psoriasis histologically, it is historically considered a "dry" disease, with significant amounts of serum not expected within lesional stratum corneum. However, this specific feature is not often mentioned within the literature. A retrospective study was undertaken to assess prevalence of serum within stratum corneum in cases of non-palmoplantar psoriasis. METHODS: We evaluated 27 specimens diagnosed histologically as psoriasis between January 2015 and June 2016. In addition to serum, we assessed for psoriasiform hyperplasia, hypogranulosis, suprapapillary thinning and parakeratosis with neutrophils. The cases were then categorized as either diagnostic for, or consistent with, psoriasis and were followed up with clinicians to assess whether the clinical course was consistent with psoriasis. RESULTS: A total of 27 hematoxylin and eosin (H&E)-stained biopsies were examined from 21 patients, with periodic acid-Schiff (PAS) performed on 20 of the biopsies. Of these, 12 biopsies had serum present (44.4%). Of the 12 lesions considered to clinically and histologically represent psoriasis, 5 (41.7%) had serum. CONCLUSION: Our results suggest serum within stratum corneum is possibly an acceptable feature within the spectrum of psoriasis histopathology and should not necessarily detract from the diagnosis.
