Characterized by small, droplike, 1-10 mm in diameter, salmon-pink papules, usually with a fine scale, a distinctive, acute clinical presentation of an eruption is known as guttate psoriasis. Guttate psoriasis is more common in people younger than 30 years of age. Secondary to group A beta-hemolytic streptococci, Streptococcus pyogenes for example, a history of upper respiratory infection often precedes the eruption by 2-3 weeks. While isolated bouts are known to occur, recurrent episodes may occur, particularly those which are the result of pharyngeal carriage of streptococci.

A nonfatal eruption, guttate psoriasis either develop into the chronic plaque-type of psoriasis or run a limited course over several weeks to a few months. Although scarring is not a problem with people who develop guttate psoriasis, postinflammatory hypopigmentation or postinflammatory hyperpigmentaion may be shown by previously affected areas.

In the United States, the guttate form of psoriasis is relatively uncommon. It occurs in less than 2% of psoriatic population in the US. People of all races, both genders equally, can get affected by this disease. In general, guttate psoriasis is believed to be the type of psoriasis that most likely to affect adolescents and children.

Pathophysiology: The precise mechanism of pathophysiology is uncertain. It is believed that an immune reaction that is triggered by a previous streptococcal infection results in guttate psoriasis. Cytokines and T lymphocytes are believed to cause the characteristic inflammatory changes appreciated on histopathologic examination of lesional skin samples. As some streptococcal products and components have been found to cross-react with normal human epidermis an autoimmune phenomenon has also been assumed.