Lymphangitis is an inflammation of the lymphatic system, which is a major component of your immune system.

Your lymphatic system is a network of organs, cells, ducts, and glands. The glands are also called nodes and can be found throughout your body. They are most apparent under your jaw, in your armpits, and in your groin.

Organs that make up the lymphatic system include your:

• tonsils, which are located in your throat
• spleen, an organ in your abdomen that purifies your blood, among other functions
• thymus, an organ in your upper chest that helps white blood cells develop

Immune cells called lymphocytes mature within your bone marrow and then travel to your lymph nodes and other organs within the lymphatic system to help protect your body against viruses and bacteria. The lymphatic system also filters a whitish-clear fluid called lymph, which contains bacteria-killing white blood cells.

Lymph travels through your body along lymphatic vessels and collects fats, bacteria, and other waste products from cells and tissues. Your lymph nodes then filter these harmful materials out of the fluid and produce more white blood cells to fight off the infection.

Infectious lymphangitis occurs when viruses and bacteria invade the vessels of your lymphatic system, typically through an infected cut or wound. Tender red streaks often radiate from the wound toward the nearest lymph glands. Other symptoms include fever, chills, and a general sense of illness.

If it’s treated quickly, lymphangitis often goes away with no ill effects. If left untreated, complications can occur, and the condition can become very serious.

Lymphangitis is sometimes incorrectly called blood poisoning. It’s also sometimes mistaken for thrombophlebitis, which is a clot in a vein.

Infectious lymphangitis occurs when bacteria or viruses enter the lymphatic channels. They may enter through a cut or wound, or they may grow from an existing infection.

The most common infectious cause of lymphangitis is acute streptococcal infection. It may also be the result of a staphylococcal (staph) infection. Both of these are bacterial infections.

Lymphangitis may occur if you already have a skin infection and it’s getting worse. This might mean that bacteria will soon enter your bloodstream. Complications such as sepsis, a life-threatening condition of body-wide inflammation, can occur as a result.

Conditions that increase your risk of lymphangitis include:

• diabetes
• immunodeficiency, or loss of immune function
• chronic steroid use
• chickenpox

A cat or dog bite or a wound made in fresh water can also become infected and lead to lymphangitis. Gardeners and farmers may develop the condition if they get sporotrichosis, a soil-borne fungal infection.

There are also noninfectious causes of lymphangitis. Inflammation of lymph vessels can occur due to malignancy: Breast, lung, stomach, pancreas, rectal, and prostate cancers are common types of tumors that can lead to lymphangitis. Lymphangitis has also been seen in those with Crohn’s disease.

Red streaks often trace the surface of the skin from the infected area to the nearest lymph gland. They may be faint or very visible and tender to the touch. They may extend from a wound or cut. In some cases, the streaks may blister.

Other symptoms include:

• chills
• swollen lymph glands
• fever
• malaise, or a general ill feeling
• loss of appetite
• headache
• aching muscles

To diagnose lymphangitis, your doctor will perform a physical exam. They’ll feel your lymph nodes to check for swelling.

Your doctor may also order tests such as a biopsy to reveal the cause of the swelling or a blood culture to see if the infection is present in your blood.