noun. 1  a. A cylindrical, usually metal casing containing the primer and charge of ammunition for firearms. 2  A case filled with high explosives, used in blasting. 3  A small modular unit designed to be inserted into a larger piece of equipment: an ink cartridge; a disposable cartridge of caulking compound. A removable case containing the stylus and electric conversion circuitry in a phonograph pickup.
Guttate psoriasis causes a rash formed of drop-shaped salmon-pink areas on the chest, arms, legs and scalp. Guttate psoriasis. Red drop-like lesions are found on the skin. Image courtesy of Dr Hon Pak.
Injury to the skin can trigger psoriatic skin changes at that spot, which is known as Koebner phenomenon. There are five main types of psoriasis: plaque, guttate, inverse, pustular, and erythrodermic. Plaque psoriasis, also known as psoriasis vulgaris, makes up about 90% of cases. It typically presents with red patches with white scales on top. Areas of the body most commonly affected are the back of the forearms, shins, around the navel, and the scalp. Guttate psoriasis has drop-shaped lesions.