Painful Post-Auricular Lymphadenopathy with Low-Grade Fever
The most likely diagnosis is acute bacterial lymphadenitis from a local scalp or ear infection, and first-line treatment is narrow-spectrum beta-lactam antibiotics (flucloxacillin or first-generation cephalosporin) after identifying the infectious source. 1, 2
Immediate Clinical Assessment
Examine specifically for:
- Scalp lesions, folliculitis, or cellulitis (post-auricular nodes drain the scalp and posterior ear) 1
- Ear canal inflammation or otitis externa (can cause regional lymphadenopathy) 1
- Vesicular lesions on the pinna, ear canal, or periauricular skin (pathognomonic for Ramsay Hunt syndrome) 3
- Ear pain with facial weakness (red flag for varicella-zoster virus infection rather than simple bacterial infection) 3
- Tympanic membrane appearance (erythematous but intact with normal mobility suggests viral infection; bulging with reduced mobility suggests acute otitis media) 3
Risk Stratification for Serious Pathology
High-risk features requiring urgent comprehensive evaluation include: 4, 1
- Node present ≥2 weeks without fluctuation
- Firm consistency or fixation to adjacent tissues
- Size >1.5 cm
- Overlying skin ulceration
- Age >40 years with tobacco/alcohol use
In this acute presentation with fever and pain, these high-risk features are unlikely, making benign infectious etiology most probable. 1, 2
Most Likely Diagnoses by Clinical Context
Acute Bacterial Lymphadenitis (Most Common)
- Methicillin-susceptible Staphylococcus aureus (49%) and Group A Streptococcus (43%) predominate in culture-positive cases 2
- Presents with tender, enlarged node and low-grade fever 2
- Treatment: Flucloxacillin or first-generation cephalosporin for uncomplicated disease 2
- Methicillin-resistant S. aureus is rare (6%) in low-prevalence settings 2
Ramsay Hunt Syndrome (If Ear Pain Present)
- Constellation of deep tearing ear pain, ear canal inflammation, and facial nerve involvement is pathognomonic 3
- Posterior cervical/post-auricular lymphadenopathy can occur with EBV infection (15% of pediatric cervical lymphadenopathy cases) 5
- Immediate treatment with acyclovir or valacyclovir plus prednisone is required to prevent permanent facial nerve damage 3
Viral Lymphadenitis
- Posterior cervical lymphadenopathy may represent Epstein-Barr virus infection, especially in children 5
- Associated with fever (70.8%), tonsillo-pharyngitis (66.6%), and splenomegaly (58.3%) 5
Treatment Algorithm
For Uncomplicated Bacterial Lymphadenitis (No Abscess)
Prescribe narrow-spectrum beta-lactam monotherapy: 2
- Flucloxacillin OR
- First-generation cephalosporin (e.g., cephalexin)
- Duration: Typically 7-10 days
- Low rates of relapse or complications with this approach 2
When to Escalate Care
Obtain CT neck with contrast if: 4, 1
- High-risk features present (see above)
- No improvement within 48-72 hours of antibiotics
- Fluctuance suggesting abscess formation
For complicated disease (abscess present): 2
- Early imaging mandatory
- Prompt surgical consultation for drainage
- Infectious diseases consultation to guide antibiotic therapy
- Consider clindamycin in addition to beta-lactam 2
Critical Management Pitfalls to Avoid
- Never perform incision and drainage or incisional biopsy alone for suspected mycobacterial infection—this leads to fistula formation and chronic drainage 4, 1
- Never assume empiric antibiotics are appropriate without identifying clear infectious signs—most adult neck masses are neoplastic, not infectious 4, 1
- Never delay imaging in high-risk patients 4
- Simple acute otitis externa never produces facial nerve paralysis; its presence mandates consideration of Ramsay Hunt syndrome or necrotizing otitis externa 3