Eosinophils are rare in biopsy specimens of psoriasis vulgaris

Abstract

Background

Histologic features of lesional biopsies can be helpful in distinguishing psoriasis subtypes from disease mimickers. However, occasionally classic histologic features are not sufficient for distinction and additional clues would be useful. There is a common belief that presence of eosinophils in skin biopsies argues against psoriasis, but actual literature is scant.

Design

Skin biopsies from 2013–2016 with a diagnosis of psoriasis were reviewed. For inclusion both histologic and clinical features were required to be consistent with psoriasis. For biopsies meeting inclusion criteria, detailed evaluation for typical histologic parameters of psoriasis, as well as presence of dermal eosinophils, was performed.

Results

Of 85 cases meeting inclusion criteria, all had either individual or grouped intra-corneal neutrophils and dilated papillary blood vessels. Diminished or complete loss of the granular cell layer was seen in 83 cases (98%) and parakeratosis was seen in 84 cases (99%). Alternatively, dermal eosinophils were seen in only 15 cases (18%). Of cases with eosinophils, none had more than 3 eosinophils upon examination of the entire dermis. Active treatment did not appear to impact presence/absence or numbers of eosinophils

Conclusion

Eosinophils are uncommon in psoriasis biopsies, and, when present, they are found in small numbers.

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