Psoriasis or not? Review of 51 clinically confirmed cases reveals an expanded histopathologic spectrum of psoriasis

Abstract

Background

Psoriasis is usually diagnosed clinically, so only non-classic or refractory cases tend to be biopsied. Diagnostic uncertainty persists when dermatopathologists encounter features regarded as non-classic for psoriasis.

Objective

Define and document classic and non-classic histologic features in skin biopsies from patients with clinically confirmed psoriasis.

Methods

Minimal clinical diagnostic criteria were informally validated and applied to a consecutive series of biopsies histologically consistent with psoriasis. Clinical confirmation required two of the following criteria: 1. classic morphology, 2. classic distribution, 3. nail pitting, 4. family history, with #1 and/or #2 as one criterion in every case

Results

Fifty-one biopsies from 46 patients were examined. Classic features of psoriasis included hypogranulosis (96%), club-shaped rete ridges (96%), dermal papilla capillary ectasia (90%), Munro microabscess (78%), suprapapillary plate thinning (63%), spongiform pustules (53%), and regular acanthosis (14%). Non-classic features included irregular acanthosis (84%), junctional vacuolar alteration (76%), spongiosis (76%), dermal neutrophils (69%), necrotic keratinocytes (67%), hypergranulosis (65%), neutrophilic spongiosis (61%), dermal eosinophils (49%), compact orthokeratosis (37%), papillary dermal fibrosis (35%), lichenoid infiltrate (25%), plasma cells (16%), and eosinophilic spongiosis (8%).

Conclusions

Psoriasis exhibits a broader histopathologic spectrum. The presence of some non-classic features does not necessarily exclude the possibility of psoriasis.

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