IMMUNOHISTOCHEMICAL STUDY OF Ki-67 ANTIGEN EXPRESSION IN DIAGNOSIS OF PSORIASIS

Background: Psoriasis is a common, chronic inflammatory skin disease characterized by scaly white papules and pinpoint bleeding on scratching. Presence of keratinocyte hyperproliferation and abnormal differentiation in the epidermis are some significant features. Histopathologically, it is difficult for the dermatopathologists to differentiate psoriasis from psoriasiform dermatitis when there is a lack of typical features. Aims: To study the Ki-67 antigen expression in the different layers of epidermis of psoriatic skin lesion and its utility in the diagnosis and to differentiate psoriasis from other psoriasiform dermatitis by studying the distribution pattern of Ki-67 immunostaining. Methods: In this cross-sectional study, a total of 91 skin lesions which were clinically labelled as psoriasis and psoriasiform dermatitis were studied, which was confirmed by histopathological examination and followed by Ki-67 immunostaining. The distribution of Ki-67 immunostaining in the supra-basal layer, basal layer and whole epidermis was studied. Results: Ki67 staining was significantly higher in the suprabasal layer and whole epidermis in psoriatic lesions compared to psoriasiform dermatitis. The suprabasal Ki-67 mitotic index was also significantly higher in psoriasis group than psoriasiform dermatitis (p <0.05). We found that in psoriasis > 50% Ki-67 positive keratinocytes are scattered in the suprabasal layer of the epidermis in comparison to the psoriasiform dermatitis which is < 50%. Conclusion: We suggest that Ki-67 labelling index can be used for diagnosing psoriasis and also can differentiate it from other psoriasiform dermatitis.