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.
Certain factors may trigger psoriasis in a person who has never had symptoms before. And for those who have psoriasis, these same factors can trigger another bout with the disease. Triggers include: 1  bacterial or viral infections, such as strep throat or the common cold. 2  diseases that weaken your immune system, such as AIDS or cancer. 3  emotional stress. 4  dry air or dry skin (particularly from changes in weather). 5  some medicines, such as beta-blockers, lithium, and anti-malaria drugs.