PSORIASIS

Psoriasis is a chronic proliferative and inflammatory condition of the skin. It is characterized by erythematous plaques covered with silvery scales particularly over the extensor surfaces, scalp, and lumbosacral region.

The pathophysiology of psoriasis involves infiltration of the skin by activated T cells which stimulate proliferation of keratinocytes. This dysregulation in keratinocyte turnover results in the formation of thick plaques. Other associated features include epidermal hyperplasia and parakeratosis. In addition, the epidermal cells fail to secrete lipids which results in flaky and scaly skin, which is typical of psoriasis.

• Psoriasis can present with different morphology in the form of plaque, guttate, rupioid, erythrodermic, pustular, inverse, elephantine, and psoriatic arthritis.

• Variation in a site is seen with the involvement of scalp, palmoplantar region, genitals, and nails.

• Any injury to the skin in patients with psoriasis in the form of either mechanical, chemical or radiational trauma induces lesions of psoriasis at that site which is called Koebner phenomenon. It indicates the activeness of disease.

• Usually, diagnosis is made by clinical morphology and site of lesions.