Which lesion is characteristic of psoriasis?

The characteristic lesion of psoriasis is scaling plaques commonly found on the knees and elbows. Psoriasis is a chronic inflammatory skin condition that is typified by well-defined, erythematous plaques covered with silvery-white scales. These plaques usually appear symmetrically on extensor surfaces, such as the knees and elbows, and can also be present on the scalp and lower back.

The pathophysiology involves an accelerated skin cell turnover, leading to the characteristic appearance and associated symptoms. The scaling is a result of the rapid proliferation of keratinocytes, which outpaces the normal maturation process of the skin. The plaques can be itchy and may become painful if they crack or become inflamed.

Other conditions, while they have distinct characteristics, do not represent the typical presentation seen in psoriasis. For instance, pruritic pustules found between the fingers indicate conditions like pompholyx or dyshidrotic eczema, while crusting vesicles around the mouth are often more aligned with herpes simplex virus infections or contact dermatitis. Hypopigmented macules on the hands may suggest conditions such as tinea versicolor or vitiligo, neither of which associates with the classic plaques of psoriasis.