Lymphadenitis

Basics

Description

Lymph nodes are inflamed causing enlargement and tenderness
- Become engorged with lymphocytes and macrophages
- May be infected
Classified by location and acuity of node enlargement
- Acute regional
  - Infection in distal extremity may result in adenitis proximally
  - Acute suppurative lymphadenitis may occur after pharyngeal or skin infection
- Causes of chronic regional and systemic lymphadenitis are mentioned in this chapter, but are more fully discussed in disease-specific chapters

Etiology

Cervical:
- Viral: common, usually bilateral adenitis
  - Epstein–Barr virus (EBV)
  - Cytomegalo virus (CMV)
  - Adenovirus (or other causes of upper respiratory infection)
- Bacterial: Common, either bilateral or unilateral, more likely to be suppurative
  - Skin origin: Staphylococcus aureus: Both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA), group A β-hemolytic Streptococcus
    - Staph risk factors discussed below
  - Pharyngeal origin: Group A β-hemolytic Streptococcus
  - Periodontal origin: Group A β-hemolytic Streptococcus and anaerobes
  - Mycobacterium tuberculosis, atypical mycobacterium – uncommon; subclinical course
  - Bartonella henselae: Cat-scratch disease; subclinical course
Axillary:
- Streptococcus pyogenes (group A β-hemolytic Streptococcus)
  - Fever, axillary pain, and acute lymphedema of arms and chest, without features of cellulitis or lymphangitis; ipsilateral pleural effusion may be present; primary source arm or hand
- Skin origin: S. aureus and group A β-hemolytic Streptococcus
- B. henselae: Cat-scratch disease
  - Most common lymph node region affected, subclinical course
Inguinal:
- Skin origin: Usually unilateral
  - S. aureus: Both MSSA and MRSA, group A β-hemolytic Streptococcus
  - Sexually transmitted disease: Can be unilateral or bilateral
  - Syphilis (primary and secondary)
  - Lymphogranuloma venereum (LGV) – Chlamydia trachomatis
  - Chancroid
  - Primary genital herpes
- B. henselae: Cat-scratch disease
  - Usually unilateral, subclinical course
- Yersinia pestis: Bubonic plague:
  - Exposure to fleas from rodents or rabbits in western U.S.
  - Seen in hunters, backpackers, rural workers
S. aureus risk factors
- Staph (MSSA and MRSA) more common in suppurative adenitis and/or abscess formation
- Risk factors for Staph infection (MSSA and MRSA):
  - Recent hospital or long-term care admission
  - Recent surgery
  - Children
  - Soldiers
  - Incarcerated persons
  - Athletes in contact sports
  - Injection drug use
  - Men who have sex with men
  - Dialysis treatments and catheters
  - History of penetrating trauma
- Additional risk factors for MRSA infection:
  - Prior MRSA infection
  - MRSA colonization
  - Area of high MRSA incidence, close contact with MRSA patient
Systemic lymphadenitis/lymphadenopathy:
- HIV
- EBV, CMV
- Toxoplasmosis, acute
- Miliary tuberculosis
- Secondary syphilis
- Leptospirosis

Pediatric Considerations

Acute unilateral cervical suppurative lymphadenitis:
- Most common at age <6 yr
- Group A Streptococcus, S. aureus, and anaerobes are most common causes
- Source is pharyngeal or scalp
- Acute torticollis possible

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