The lymphatic system is a network of vessels (channels), nodes (glands) and organs. It functions as part of the immune system to protect against and fight infection, inflammation, and cancers. It also functions in the transport of fluids, fats, proteins, and other substances within the body.

The lymph glands, or nodes, are small structures that filter the lymph fluid. There are many white blood cells in the lymph nodes to help fight infection.

Lymphadenitis and lymphangitis are common complications of bacterial infections.

Lymphadenitis involves inflammation of the lymph glands. It may occur if the glands are overwhelmed by bacteria, virus, fungi, or other organisms and infection develops within the glands. It may also occur as a result of circulating cancer cells or other inflammatory conditions.

The location of the affected gland(s) is usually associated with the site of the underlying infection, tumor, or inflammation. It commonly is a result of a cellulitis or other bacteria infection (usually infection by streptococci or staphylococci).

Lymphangitis involves the lymph vessels/channels, with inflammation of the channel and resultant pain and systemic and localized symptoms. It commonly results from an acute streptococcal or staphylococcal infection of the skin (cellulitis), or from an abscess in the skin or soft tissues.

Lymphangitis may suggest that an infection is progressing, and should raise concerns of spread of bacteria to the bloodstream, which can cause life-threatening infections. Lymphangitis may be confused with a clot in a vein (thrombophlebitis).