What are the potential causes and management options for a patient with unilateral tonsillar enlargement?

Unilateral Tonsillar Enlargement: Evaluation and Management

Immediate Action Required

Unilateral tonsillar enlargement requires urgent evaluation to exclude malignancy, particularly lymphoma, which presents with asymmetric tonsils in the majority of cases, and tonsillectomy should be performed when suspicious features are present or close observation is not feasible. 1

Risk Stratification for Malignancy

The decision to proceed with immediate tonsillectomy versus observation depends on specific high-risk features:

High-Risk Features Mandating Tonsillectomy:

• Enlarged cervical lymph nodes - strongest predictor of malignancy 2
• Suspicious tonsillar appearance (ulceration, necrosis, firmness, fixation) 2
• Age >40 years 2
• History of malignancy or immunocompromise 2
• Progressive enlargement over time 1
• Presence of B-symptoms (fever, night sweats, weight loss) 1

Lower-Risk Features Allowing Observation:

• Asymptomatic asymmetry noted incidentally 3
• Young children (age <16 years) without other concerning features 3
• No palpable lymphadenopathy 2
• Normal tonsillar surface appearance 2

Critical Diagnostic Pitfall

Apparent unilateral enlargement is frequently spurious - in 15% of cases, the "clinically larger" tonsil is actually smaller when measured by pathology, and in 36% of cases there is no size difference at all when both tonsils are examined after removal. 3 This occurs because asymmetry of the tonsillar pillars creates the illusion of size difference. 3

Management Algorithm

For High-Risk Patients:

• Proceed directly to tonsillectomy for tissue diagnosis 2
• Perform bilateral tonsillectomy even when asymmetry appears unilateral, as bilateral disease can present with unilateral clinical findings 4
• Send tissue for comprehensive pathologic evaluation including immunohistochemistry 1

For Low-Risk Patients (Children Without Suspicious Features):

• Close clinical observation is acceptable with re-examination every 2-4 weeks 3
• Proceed to tonsillectomy if:
  • Any suspicious features develop during observation 2
  • Progressive enlargement occurs 1
  • Patient/family preference for definitive diagnosis 3
  • Concurrent indication exists (recurrent infections meeting Paradise criteria or obstructive sleep apnea) 5

Malignancy Rates by Population

The incidence of malignancy varies dramatically by age and presentation:

• Children with isolated asymmetry: 0-5% malignancy rate 3, 1
• Adults with asymmetry and suspicious features: 20% malignancy rate 2
• Most common malignancies: Non-Hodgkin lymphoma (both lymphocytic and histiocytic types), squamous cell carcinoma in adults 6
• Rare presentations: CLL/SLL, extramedullary plasmacytoma, Hodgkin's disease, leukemia, metastatic disease 6, 4

Key Clinical Point

All six patients diagnosed with tonsillar lymphoma in one pediatric series presented with clinically apparent tonsillar asymmetry at their first visit, even though B-symptoms were absent initially. 1 This underscores that while most asymmetric tonsils are benign, most tonsillar lymphomas present with asymmetry, making careful evaluation essential. 1

When Obstructive Sleep Apnea Coexists

If the patient has concurrent OSA symptoms with unilateral enlargement:

• Adenotonsillectomy is first-line treatment once malignancy is excluded 7, 5
• Complete bilateral tonsillectomy is preferred over partial procedures, as residual tissue may harbor disease 7
• Concurrent adenoidectomy provides superior outcomes compared to tonsillectomy alone 7, 5
• Intraoperative dexamethasone (0.5 mg/kg, maximum 8-25 mg) reduces postoperative complications 7, 5

Documentation Requirements

When choosing observation over immediate surgery, document:

• Specific absence of high-risk features 2
• Tonsillar measurements and appearance 3
• Patient/family counseling about warning signs 1
• Follow-up plan with specific timeframes 3