• Psoriasis is generally asymptomatic, but can occasionally become quite pruritic and uncomfortable, particularly during acute flare-ups or when lesions involve the scalp or intertriginous areas.

• Those who have psoriasis commonly recognize the “Köbner” phenomenon in which new lesions appear at sites of injury or trauma to the skin.

• Noxious stimuli, such as scratching and rubbing, or sunburn can elicit a Köbner reaction (Figs. 14.5 and 14.6).

• Painful fissures may occur when lesions are present over joints, in the axillae or intragluteal fold, or on the palms and soles.

• Psoriasis can be a major blow to one's ego. It may stifle social activities and sexual spontaneity, interfere with job opportunities and inhibit participation in sports, and the use of beaches and public swimming pools.

• The psychological ramifications of psoriasis—anxiety, social isolation, alcoholism, depression, suicidal ideation—are possible associations and outcomes of this essentially benign skin disease.

Factors that may adversely influence psoriasis include the following:

• Stress. Stress has been implicated as a trigger in acute exacerbations and in progression of psoriasis.

• Alcohol. Alcohol overindulgence has been reputed to exacerbate psoriasis.

• Drugs. Antimalarials, beta-blockers, angiotensin-converting enzyme inhibitors, certain nonsteroidal anti-inflammatory drugs (e.g., indomethacin), systemic interferon, and lithium carbonate have been reported to worsen psoriasis; however, pre-existing psoriasis is not necessarily a contraindication to their use. Both systemic, and less likely, potent topical steroids have been known, albeit rarely, to trigger a severe, acute, potentially fatal pustular psoriasis (pustular psoriasis of von Zumbusch) that tends to occur after withdrawal of the medication.

• Physical trauma. Surgery, thermal and chemical burns, and infections potentially exacerbate psoriasis. For example, an increase in psoriasis activity has been observed in patients who are, or become, infected with the human immunodeficiency virus (HIV).

• Sunlight. A small minority of patients find that their psoriasis is worsened by strong sunlight, probably via the Köbner reaction (see Figs. 14.5 and 14.6), whereas the vast majority of patients generally discover that sunlight is beneficial.

• Psoriasis is an erratic condition with an unpredictable, waxing- and-waning course. It has no known cure; however, there are numerous methods to keep it under control.

• Many patients tend to improve during the summer and worsen during the colder periods of the year. This fluctuation is presumably the result of the positive influence of sunlight.