Cysts are usually noncancerous and have a sac-like structure that can contain fluid, pus, or gas. Cysts are common and can occur anywhere on the body. Cysts are often caused by infection, clogging of sebaceous glands, or around earrings.
All unusual lumps need to be investigated. Some cysts are cancerous and early treatment is vital. If left untreated, benign cysts can cause serious complications including: Infection – the cyst fills with bacteria and pus, and becomes an abscess.
A boil is a bacterial skin infection of a hair follicle. Boils contain pus. Boils are usually caused by staphylococcal bacteria. Boils are also known as furuncles.