الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Hyperproliferative skin disorders (HSD) consist of various types of pathologies that present different skin manifestations in terms of severity and distribution of lesions. They are commonly characterized by altered epidermal homeostasis causing uncontrolled skin proliferation and dysregulated differentiation.
Cyclin dependent kinases are proline-directed serine/threonine protein kinases that are traditionally activated upon association with a regulatory subunit.
In humans, there are 13 different CDKs (CDK1 - CDK13) that are highly expressed in mitotic cells. CDK5, a part of these cyclins, has functions in both terminally differentiated and proliferating cells.
The nuclear protein Ki-67 is being associated with cellular proliferation.
The present study was carried out on a total of 80 individuals attending the Outpatient Clinic of Dermatology, Venereology and Andrology at Benha University Hospital, included sixty patients, twenty patients with psoriasis (plaque type), twenty patients with verruca vulgaris and twenty patients with seborrhiec keratosis (acanthotic or hyperkeratotic), also included twenty healthy volunteers who were age and sex matched with the patient group.
In this study dermoscopic, histopathological, and immunohistochemical expression of CDK5, and Ki67 in the three hyperproliferative skin diseases (psoriasis, verruca, and seborrheic keratoses) were investigated.
The expression of CDK5, paralleled with activity of psoriasis as there was statistically significant relation between CDK5 and course of the disease with all stationary courses had negative CDK5, and half of progressive course patients had a positive CDK5, and there was statistically significant relation between CDK5 and diffuse acanthosis pattern, these results may explain the role of CDK5 in the pathogenesis of psoriasis.
This study revealed a positive correlation between CDK5 and histopathological changes of verruca patients there was statistically significant relation regarding diffuse acanthosis pattern and CDK5 expression, also there is statistically significant relation regarding parakeratosis and CDK5 expressions, and this may show the possible role of CDK5 in the pathogenesis of hyperproliferative keratinocytes disorders.
This study revealed that CDK5 expressed more in verruca than in psoriasis, seborrheic keratoses and controls. However, Ki67 expressed more in psoriasis than in verruca, seborrheic keratoses and controls. There is statistically significant relation between the studied groups regarding nuclear expression of either CDk5 or Ki67 expression. These results may explain the role of CDK5 and Ki67 biomarkers in hyperproliferative keratinocytes disorders.
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