What is the approach to diagnosing and treating lymphadenitis in the neck, considering patient demographics, past medical history, and symptoms such as fever and pain?

Approach to Neck Lymphadenitis

If the neck mass shows clear signs of bacterial infection (warmth, erythema, localized swelling, tenderness, fever), prescribe a single course of broad-spectrum antibiotics covering Staphylococcus aureus and Streptococcus pyogenes, but mandate reassessment within 2 weeks—if not completely resolved, immediately pursue malignancy workup regardless of partial improvement. 1

Initial Clinical Assessment: Distinguish Infectious from Malignant

Signs Suggesting Bacterial Infection

• Local findings: warmth, erythema of overlying skin, localized swelling, and tenderness to palpation 1
• Systemic findings: fever, tachycardia, rhinorrhea, odynophagia, otalgia, or odontalgia 1
• Temporal relationship: mass developed within days/weeks of upper respiratory infection, dental problem, trauma (including insect bites), travel, or animal exposure 1

Red Flags for Malignancy (Immediate Advanced Workup Required)

• Duration: present ≥2 weeks without significant fluctuation OR uncertain duration 1
• Physical characteristics: fixation to adjacent tissues, firm consistency, size >1.5 cm, or ulceration of overlying skin 1
• Location: supraclavicular or posterior cervical nodes carry much higher malignancy risk than anterior cervical nodes 2
• Demographics: age >40 years, male sex, white race 3
• Absence of infectious etiology 1

Critical Diagnostic Algorithm

Step 1: History and Physical Examination

Perform targeted examination including: 1

• Skin and scalp (cutaneous malignancy)
• Otoscopy (unilateral serous otitis suggests nasopharyngeal malignancy)
• Complete cranial nerve assessment
• Oral cavity with digital examination of tongue and floor of mouth
• Oropharynx with palpation of tongue base and tonsillar fossae
• Nasopharynx, hypopharynx, and larynx visualization
• Bimanual palpation of floor of mouth and entire neck
• Salivary glands and thyroid palpation

Step 2: Laboratory Testing

• If infectious suspected: white blood cell count and C-reactive protein (elevated in 94% of bacterial cases) 4
• If mycobacterial suspected: tuberculin skin test (PPD), chest radiograph 2, 5
• If persistent/suspicious: complete blood count, erythrocyte sedimentation rate, tuberculosis testing 6

Step 3: Imaging

• Ultrasound: first-line to differentiate bacterial lymphadenitis (single node with hypoechoic core) from other etiologies; 87.5% correlation with clinical/surgical findings 4
• CT with contrast: if ultrasound inconclusive or to characterize adenopathy and assess for retropharyngeal edema/phlegmon 5
• MRI: if CT contraindicated 1

Step 4: Tissue Diagnosis

• Fine-needle aspiration (FNA): for cytology and culture when malignancy or mycobacterial infection suspected 1, 5
• Core needle or excisional biopsy: if FNA non-diagnostic 6, 3

Treatment Based on Etiology

Bacterial Lymphadenitis (Acute Unilateral)

• Antibiotic choice: broad-spectrum covering S. aureus and S. pyogenes (40-80% of acute unilateral cases) 7
• Duration: single course 1
• Surgical drainage: indicated if suppurative/abscess formation (29.4% of cases require incision and drainage) 4
• Mandatory follow-up: reassess within 2 weeks; if not completely resolved, pursue malignancy workup 1
• Additional follow-up: if resolved, reassess again in 2-4 weeks to monitor for recurrence (which mandates malignancy workup) 1

Mycobacterial Lymphadenitis

Critical distinction required: 2, 5, 8

Nontuberculous Mycobacteria (NTM)

• Demographics: primarily children aged 1-5 years; 80% caused by Mycobacterium avium complex 2
• Treatment: complete surgical excision without chemotherapy (95% success rate) 5
• Avoid: incisional biopsy or drainage alone—leads to sinus tract formation and chronic drainage 2, 5

Mycobacterium tuberculosis

• Demographics: >90% of mycobacterial lymphadenitis in adults 2, 5
• Treatment: systemic antituberculosis medication (treat as systemic disease) 8
• Public health: requires reporting and contact tracing 2
• PPD interpretation: ≥15 mm in child with granulomatous adenitis suggests tuberculosis; start treatment while awaiting culture 5

Viral Lymphadenopathy

• Most common cause: upper respiratory tract infections (22-53% of cases) 2
• Specific pathogens: Epstein-Barr virus, Cytomegalovirus, Coxsackievirus, Rubella 2
• Management: self-limited; typically resolves with infectious symptoms or within days of completing treatment 1

Special Population Considerations

HIV/Immunocompromised Patients

• Disseminated MAC: common with CD4 <50 cells/μL, causes suppurative lymphadenopathy 2
• Immune reconstitution inflammatory syndrome: paradoxical lymphadenitis after starting antiretroviral therapy 2, 5
• Cytomegalovirus: high mortality if misdiagnosed 2

Children

• Kawasaki disease: consider if cervical lymphadenopathy ≥1.5 cm with fever ≥5 days plus ≥4 principal features (oral changes, conjunctival injection, rash, extremity changes) 1
• Distinguish from bacterial: multiple enlarged nodes with retropharyngeal edema in Kawasaki vs. single node with hypoechoic core in bacterial lymphadenitis 1

Critical Pitfalls to Avoid

1. Never use empiric antibiotics without infectious signs/symptoms—delays malignancy diagnosis 1
2. Partial resolution on antibiotics may represent infection in underlying malignancy—requires full workup 1
3. Avoid corticosteroids—masks histologic diagnosis of lymphoma 6, 3
4. Do not perform incisional biopsy for suspected mycobacterial disease—causes chronic fistula formation 2, 5
5. Distinguish TB from NTM before treatment—TB requires drug therapy and public health tracking; NTM requires surgical excision 2
6. Supraclavicular and epitrochlear nodes are abnormal—mandate aggressive workup for malignancy 6, 3