AbstractIntroduction. Psoriasis is a chronic inflammatory skin disease with hyperproliferation, abnormal differentiation and inflammatory infiltration in epidermis and dermis. Sometimes it is clinically and histopathologically challenging to distinguish psoriasis from other non-psoriatic psoriasiform dermatoses (NPPD) like eczema, pityriasis rosea, pityriasis rubra pilaris, and lichen simplex chronicus. Ki-67 is a non-histone nuclear protein complex that regulates the cell cycle and is the most

more »

... widely used proliferation immunohistochemistry (IHC) marker. Its levels have been shown to be raised in psoriasis compared to normal skin.Aim. To elucidate and compare expression of IHC Ki-67 in psoriasis and NPPD, correlate these levels with clinical variants and disease severity in psoriasis and to observe change in levels with demographic and psoriasis-related variables.Material and Methods. Thirty patients, each with clinically diagnosed psoriasis (cases), and NPPD (controls) were enrolled. Biopsy was taken for histopathology and IHC Ki-67 immunohistochemistry. Statistical analysis was performed.Results. We found a significantly higher expression of IHC Ki-67 in psoriasis as compared to all types of NPPD. The higher level of Ki-67 in pustular and erythrodermic psoriasis compared to plaque-type emphasizes the greater severity and activity of these forms. The Ki-67 expression was found to increase with increasing body surface area involvement and disease severity (PASI) in chronic plaque type. Pityriasis rubra pilaris had the highest Ki67 expression among NPPD group.Conclusion. Ki-67 is a promising tool with diagnostic and prognostic utility in psoriasis, particularly when it comes to its differentiation from nonpsoriasis psoriasiform disorders.