Abstract
Background: Inverse psoriasis represents an infrequently described form of psoriasis in intertriginous areas. Lesions typically present as well demarcated, smooth plaques that may be macerated and have a characteristic absence of typical psoriasiform scale. Histopathologic descriptions are commonly grouped in with those of plaque psoriasis, but little has been done to characterize the histological features of inverse psoriasis. Methods: A single institution, retrospective cohort study was performed to review biopsy slides for psoriasis occurring in typical intertriginous areas. Patients charts were reviewed and only those where the clinical diagnosis of inverse psoriasis was also favored were included. Slides were evaluated for typical and atypical features of psoriasis. Results: 12 patients met inclusion criteria 58.3% male and 41.7% female, 18-86 years of age with biopsies obtained between April 2011 and October 2020. Classical features of psoriasis including hypogranulosis, confluent parakeratosis with neutrophils and thinning of the suprapapillary plate were seen in 100%. Other classic features such as regular psoriasiform acanthosis and dilated-tortuous dermal vessels were seen in 91.7%. Atypical features of psoriasis observed were spongiosis (83.3%), eosinophils (66.7%) and focal serum in the scale (41.7%). Conclusions: While inverse psoriasis commonly exhibits histopathologic features considered to be classic for psoriasis, it is not unusual for inverse psoriasis to show findings considered atypical for plaque psoriasis such as dermal eosinophils, epidermal spongiosis, and focal serum in the scale.
Financial Disclosure:
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