A benign cyst is a fluid-filled sac that can form in various parts of the body. It is usually harmless and does not cause any symptoms. The term 'benign cyst' is derived from the Latin word 'benignus, ' which means gentle or kind. The most common type of benign cyst is a sebaceous cyst, which is caused by a blocked sebaceous gland. These cysts are typically found on the face, neck, scalp, and upper back. WEN is an acronym for 'walled-off epidermal nevus, ' which is a type of benign cyst.