People often describe localized swollen areas on, or under, the skin as lumps or bumps. While bumps on, or under, the skin may result from conditions that give rise to a skin rash, many other conditions can result in solitary raised lumps on the skin. Infections, tumors, and the body's response to trauma or injury can all lead to lumps or bumps that appear to be located on or underneath the skin. Depending upon the cause, skin lumps or bumps may vary in size and be firm or soft to the touch. The overlying skin may be reddened or ulcerated. Skin bumps may or may not be painful or tender, depending upon the cause of the lesions.