Acute lymphadenitis is a rapid, usually painful enlargement of lymph nodes triggered by bacterial or viral infection. Typical features develop over hours to days and include:

1. Swollen, tender node
   A single node or regional group suddenly enlarges to pea-to-walnut size; the overlying skin feels hot and is painful to touch.
2. Red, warm skin
   The surface becomes flushed and edematous as inflammation spreads from node to subcutaneous tissue.
3. Fluctuant mass
   Central liquefaction produces a soft, “water-bed” sensation, indicating abscess formation.
4. Fever and chills
   Temperature often rises to 38–39 °C with rigors, malaise, and night sweats.
5. Spontaneous drainage
   If untreated, the abscess may rupture, releasing creamy pus and leaving a chronic sinus.
6. Restricted movement
   Nodes in the neck, axilla, or groin limit head, arm, or leg motion because of pain and muscle splitting.
7. Associated source signs
   Look for concurrent pharyngitis, dental infection, skin wound, or sexually transmitted genital ulcer that seeds the affected node chain.

Prompt antibiotic therapy and—if fluctuant—surgical drainage prevent progression to sepsis or chronic fistulation.