Suppurative Infections of Lymph and Blood Vessels
Definition
Suppurative infections of lymphatic and vascular structures involve pus-forming inflammation due to bacterial invasion. They affect:
- Lymphatic vessels → Lymphangitis
- Lymph nodes → Lymphadenitis
- Blood vessels → Vasculitis
- Subcutaneous tissue → Cellulitis
These infections may coexist or evolve into each other, with the potential for abscess, phlegmon, fistula, or sepsis if not treated early.
1. Cellulitis
Definition
Acute bacterial infection of the dermis and subcutaneous fat layer.
Etiology
- Streptococcus pyogenes (most common)
- Staphylococcus aureus, including MRSA
Risk Factors
- Diabetes mellitus
- Immunosuppression
- Skin trauma or ulcers
- Fungal infections (interdigital, tinea pedis)
- Lymphoedema
Clinical Signs
- Swelling
- Erythema (redness)
- Heat
- Tenderness
- Ill- defined margins
- +/- Fever and malaise
Common locations: Lower limbs, face
Treatment
- Empirical antibiotics: e.g. penicillin, cephalexin, clindamycin
- Elevation and rest of limb
- Treat predisposing conditions
2. Lymphangitis
Definition
Inflammation of the lymphatic vessels, often arising from skin or soft tissue infections (e.g., cellulitis, abscess)
Causes
- Streptococcus pyogenes (most common)
- Staphylococcus aureus
- Carcinoma infiltration (rare, chronic form)
Mechanism
Bacteria spread through lymphatic channels, triggering inflammatory response
Clinical Features
- Tender red streaks (like a net or spider-web) radiating from infection site toward lymph nodes
- Pain
- Swelling
- Fever and malaise
May be mistaken for DVT in lower limb
Treatment
- Antibiotics (penicillin, cephalosporins)
- Drain pus if abscess forms
- Treat underlying infection
3. Lymphadenitis
Definition
Inflammation of lymph nodes, often from extension of a local infection
Types
- Serous Lymphadenitis – early, non- purulent, mild
- Purulent Lymphadenitis – progressive, pus formation
- Chronic Lymphadenitis – from TB, carcinoma, or unresolved acute phase
Clinical Signs
- Enlarged, tender, and warm lymph nodes
- Fever
- Overlying skin may be red
- In purulent form: fluctuation, drainage, fistula possible
Complications
- Phlegmon
- Fistula
- Abscess
- Chronic infection
Treatment
- Serous: Antibiotics + physiotherapy
- Purulent: Incision + drainage + antiseptics
- Underlying cause must always be treated (e.g. dental infection, TB)