Two groups were constituted, one with 20 subjects with the histological diagnosis of psoriasis and the other with 15 subjects with the histological diagnosis of psoriasiform dermatitis. The extents of acanthosis, basal membrane disruption, and thinning of suprapapillary epidermal plates in psoriasis group were found to be significantly greater than that in psroiasiform dermatitis group. As a conclusion, grading the histopathological parameters may indicate some clues which may help in the histological diagnosis of atypical froms of psoriasis. Key words Psoriasis, psoriasiform dermatitis, histology Psoriasiform tissue reactions include the disorders which mimic psoriasis either clinically or histologically. The diagnosis of psoriasis is usually done according to the unique clinical pattern of the disease.
Histopathological confirmation is mandatory when atypical clinical aspects are present.
In this study, psoriasis and psoriasiform dermatitis groups were formed of the patients who were previously diagnosed according to the histological criteria. By grading those histological parameters the two groups were compared for the extent of the histological parameters. The relations between the extent of histological parameters were also evaluated in each group, in order to find out whether there were a correlation between them. Clinical and histopathological review of the files and biopsy specimens were performed by dividing the patients into two groups according to their histopathological diagnoses. Group 1 consisted of 20 subjects with the clinical and histopathological diagnosis of psoriasis vulgaris, where Group 2 consisted of 15 subjects with one of the clinical diagnoses of lichen simplex chronicus, eczematous dermatitis, lichen planus or atypical clinical forms of psoriasis and each with the histological diagnosis of psoriasiform dermatitis mimicking psoriasis according to the microscopic features.