Introduction
This topic covers purulent (suppurative) infection of the lymphatic system: inflammation of lymphatic vessels (lymphangitis) and of lymph nodes (lymphadenitis), and the chronic consequence of lymphatic obstruction, elephantiasis (chronic lymphoedema). Lymphatic involvement usually follows a local purulent focus in the skin or soft tissues, so it is closely linked to the topics on skin infections and abscesses.
Lymphangitis
Lymphangitis is acute inflammation of the lymphatic vessels, most often caused by Streptococcus pyogenes (beta-haemolytic streptococcus), less often by Staphylococcus aureus. The portal of entry is a wound, a fissure, an insect bite, a furuncle, an infected ulcer, or a erysipelas-type skin infection. Bacteria spread from the primary focus into the superficial lymphatic channels, which become inflamed and thrombosed.
- Clinical picture: painful, red, sharply demarcated streaks running along the limb towards the regional lymph nodes.
- Systemic signs: fever, chills, malaise, headache; tachycardia in severe cases.
- Regional lymph nodes are enlarged and tender; the limb may be swollen and oedematous.
- Differential diagnosis includes superficial thrombophlebitis (the red line follows a vein, the lymphatic streak is more diffuse and tender along its course), deep vein thrombosis, and cellulitis without lymphatic spread.
Treatment is mainly conservative: systemic antibiotics effective against streptococci and staphylococci (for example a penicillinase-resistant penicillin or a first-generation cephalosporin; the choice depends on local resistance and severity), rest and elevation of the limb, and treatment of the portal of entry. Warm moist dressings may be applied. Surgery is needed only if a collection or abscess forms.