Abstract: Objective To analyze clinical manifestations and histopathological features of 6 subtypes of psoriasis presenting mainly as skin manifestations. Methods Clinical and histopathological data were collected from 313 patients with psoriasis in the Department of Dermatology of Xijing Hospital between 2013 and 2017, and analyzed retrospectively. Results Among the 313 patients, there were 31 patients with guttate-type psoriasis mainly induced by upper respiratory tract infections， 60 with plaque psoriasis with the main precipitating factors being upper respiratory tract infections, overexertion, cold weather and so on, 42 with erythrodermic psoriasis induced mainly by the withdrawal of systemic glucocorticoids, 60 with generalized pustular psoriasis with the main precipitating factors being upper respiratory tract infections, pregnancy, drugs and so on, 60 with palmoplantar pustulosis without definite precipitating factors, and 60 with acrodermatitis continua without definite precipitating factors. The 6 subtypes of psoriasis had similar typical pathological manifestations, including parakeratosis, Munro′s microabscess and/or spongiform pustules of Kogoj, thinning or absence of the granular layer, psoriasis-like epidermal hyperplasia, capillary ectasia in the dermal papillae, lymphocytic infiltration and so on. Atypical pathological manifestations were observed in 98 （31%） of the 313 patients, which included 4 with guttate type psoriasis （13%）, 3 with plaque psoriasis （5%）, 12 with erythrodermic psoriasis （29%）, 41 with generalized pustular psoriasis （68%）, 12 with palmoplantar pustulosis （20%） and 26 with acrodermatitis continua （43%）. These atypical pathological manifestations included serous fluid exudation, irregular epidermal hyperplasia, non-neutrophilic spongiosis, keratinocyte necrosis, dermal neutrophilic infiltration and dermal eosinophilic infiltration. Conclusions Different subtypes of psoriasis have different clinical manifestations and similar typical histopathological features. Atypical pathological features can interfere with the diagnosis of psoriasis, and attention should be paid to the differential diagnosis.

Key words: Psoriasis, Retrospective studies, Clinical manifestation, Histopathology