Suppurative Lymphadenitis
C. Cameron Yin, MD, PhD
Key Facts
Terminology
Acute lymphadenitis caused by bacterial, fungal, or some viral infections
Etiology/Pathogenesis
Common bacteria: Staphylococcus and Streptococcus
Clinical Issues
Regional lymph nodes draining pyogenic inflammation, e.g., dental abscess, upper respiratory infection, appendicitis, or infected wound
Microscopic Pathology
Dilated sinuses with weakly eosinophilic proteinaceous fluid and many neutrophils and macrophages
So-called sinus catarrh
Neutrophils infiltrate lymph node parenchyma; form microabscesses
Bacteria may be free or phagocytosed
Fungal hyphae; viral inclusions
Perilymphadenitis due to involvement of perinodal fibroadipose tissue
Ancillary Tests
Gram stain is useful in identifying presence and nature of bacteria
Bacteriologic studies, including smears and cultures, are indispensable for identifying etiology
Top Differential Diagnoses
Cat scratch lymphadenitis
Lymphogranuloma venereum lymphadenitis
Classical Hodgkin lymphoma with necrosis
 A lymph node obtained from a patient with suppurative lymphadenitis. The lymph node in this field is entirely replaced by granulocytes (pus)  and surrounded by histiocytes and lymphocytes  . |
 Gram stain of a smear from a lymph node obtained from a patient with suppurative lymphadenitis. Numerous Gram-positive bacteria are present  . |
TERMINOLOGY
Synonyms
Acute lymphadenitis
Pyogenic lymphadenitis
Definitions
Acute lymphadenitis usually caused by bacterial, fungal, or some viral infections
ETIOLOGY/PATHOGENESIS
Infectious Agents
Common bacteria: Staphylococcus and Streptococcus
Nontuberculous mycobacteria
Variety of fungi
Can also occur after bacillus Calmette-Guérin (BCG) vaccination
CLINICAL ISSUES
Epidemiology
Incidence
Suppurative lymphadenitis is uncommon in developed countries
Due to availability of antibiotic treatment
Age
More common in children
Gender
No gender predilection
Ethnicity
Seen in all ethnic groups
Site
Regional lymph nodes draining pyogenic inflammation
Dental abscess, upper respiratory infection, appendicitis, or infected wound
More commonly in superficial nodes, particularly axillary and inguinal nodes
Presentation
Lymph node(s) variably enlarged
Soft and tender
Overlying skin is red and edematous
Rarely, abscess or sinus formation
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