The main symptom of psoriasis is the characteristic lesions. Individual patients may have very different types of lesions. Lesions generally appear as very small, dot-like, red spots at first, then gradually enlarge. The affected skin thickens and often becomes dry, cracked and encrusted. These raised patches are typically swollen (edema), red (erythema) and are often itchy. Lesions are typically covered with flaky, silvery, yellow-white scales. Lesions on the legs may have a blue or purple tint. In children, psoriasis lesions are generally not as thick and may be less scaly. Children also develop facial lesions more often than adults.

The scales on the surface come off easily and are constantly shed. Those below the surface are more difficult to remove and, when removed, often leave tiny bleeding points (Auspitz’s sign). The skin beneath is generally very red and may be tender and painful. In dark-skinned individuals, the lesions beneath the scale layer may be the same color as the rest of the skin instead of a bright red color.

Lesions vary in size and shape, but the borders are distinct. There is usually only one or a few patches, but they may cover large areas of skin and merge into each other. The outlines are usually circular or oval. Sometimes, the lesions are surrounded by a ring of pale skin (Woronoff’s ring). When psoriasis is actively expanding, the itching may be more severe.

Lesions may occur anywhere on the body and can appear suddenly or gradually. In many cases, lesions appear on both sides of the body symmetrically. They frequently occur at sites of skin injury and on the scalp, knees, elbows, naval area, lower back, buttocks and genitalia. They may also occur on the palms, soles, fingernails, toenails or even inside the mouth. The lesions may affect body movement and flexibility and can be disabling when they appear in certain areas (e.g., palms, soles). The itchiness associated with severe cases can also disrupt a person's ability to sleep at night.

Other signs and symptoms may include:

• The nails often become pitted. A yellow-brown staining of the nail, lifting of the nail from the nail bed (onycholysis) and ridging and thickening of the nail (nail dystrophy) may also occur.
  
  
• Unaffected skin may become thin and easily torn.
  
  
• The eyes may burn, itch or have discharge. Inflammation of the eyelids (blepharitis) or inner eye lining (conjunctivitis) may occur.
  
  
• When arthritis is associated with psoriasis, joint involvement occurs after skin lesions are already apparent.

It is important to note that with very mild cases of psoriasis, a person may be completely unaware of the condition. However, most cases of psoriasis are moderate and trigger symptoms.