What does it mean if lymph nodes become enlarged and palpable?

Enlarged Lymph Nodes: Diagnostic Significance and Evaluation

Enlarged (palpable) lymph nodes indicate an immune response to infection, inflammation, or malignancy and require systematic evaluation to determine the underlying cause.

Causes of Lymph Node Enlargement

Lymph node enlargement can result from several pathological processes:

1. Infectious causes:

   • Bacterial, viral, fungal, or parasitic infections
   • Reactive lymphadenopathy due to localized or systemic infections

2. Malignant causes:

   • Primary lymphoid malignancies (lymphomas)
   • Metastatic spread from solid tumors
   • Leukemias with lymph node involvement

3. Inflammatory/autoimmune causes:

   • Rheumatologic disorders
   • Sarcoidosis
   • Drug reactions

Diagnostic Approach

Physical Examination Characteristics

When evaluating enlarged lymph nodes, assess:

• Size: Nodes >1.5 cm in diameter are generally considered pathologically enlarged 1
• Consistency: Firm, hard, or rubbery consistency may suggest malignancy
• Mobility: Fixed nodes often indicate malignant infiltration
• Tenderness: Painful nodes typically suggest inflammatory processes
• Distribution: Localized vs. generalized lymphadenopathy
• Associated symptoms: Fever, night sweats, weight loss (B symptoms)

Diagnostic Testing Algorithm

1. Initial evaluation:

   • Complete history and physical examination
   • Complete blood count with differential
   • Liver function tests and LDH 1
   • Targeted imaging based on location and suspected etiology

2. For localized lymphadenopathy:

   • Consider infectious etiology in the drainage area
   • Ultrasound may help characterize the node

3. For persistent or suspicious lymphadenopathy:

   • Fine-needle aspiration (FNA) is recommended for palpable nodes, especially those ≥1.5 cm 1
   • Excisional biopsy is indicated when:
     • FNA is negative but clinical suspicion remains high
     • Lymphoma is suspected (provides better architectural information)
     • Node is ≥1.5 cm and firm, irregular, clustered or fixed 1

4. Advanced imaging:

   • CT scans of chest, abdomen, and pelvis for evaluation of internal nodes
   • PET/CT may be considered for staging when malignancy is suspected 1

Special Considerations

Lymphadenopathy Location

The location of enlarged lymph nodes often provides diagnostic clues:

• Cervical: Consider upper respiratory infections, head and neck malignancies
• Supraclavicular: High suspicion for malignancy, especially left-sided nodes (Virchow's node)
• Axillary: Consider breast malignancy, cat-scratch disease, or upper extremity infections
• Inguinal: Often reactive due to lower extremity infections, but can indicate genital malignancies 1

Warning Signs for Malignancy

Be particularly concerned about:

• Firm, non-tender, fixed nodes
• Persistent enlargement >2 weeks without obvious infection
• Supraclavicular location
• Associated B symptoms (fever, night sweats, weight loss)
• Size >2 cm without signs of infection 2

Common Pitfalls

1. Overlooking small but significant nodes: Even nodes ≤2 cm may yield diagnostic information in suspected lymphoma 2

2. Assuming all enlarged nodes are infectious: Up to 25% of patients with non-palpable lymph nodes may harbor micrometastases 1

3. Delaying biopsy: For persistent lymphadenopathy without clear infectious cause, early biopsy is warranted

4. Missing rare causes: Conditions like Yersinia enterocolitica can cause significant lymphadenopathy that may mimic malignancy 3

5. Inadequate follow-up: Lymphadenopathy that doesn't resolve requires continued monitoring and potential rebiopsy

Conclusion

Enlarged lymph nodes represent the body's response to various pathological processes. A systematic approach to evaluation with appropriate diagnostic testing is essential to determine the underlying cause and guide treatment decisions. When malignancy is suspected, prompt biopsy is critical to establish diagnosis and initiate appropriate therapy.