000 Low Density Lymphadenopathy

TCV Finding: Low-Density Lymphadenopathy in the Chest
- What is it:
  - Low-density lymphadenopathy refers to the enlargement of lymph nodes in the chest, where the lymph nodes demonstrate
  - a decreased density (hypodensity) on imaging,
  - typically seen on CT scans.
- This low-density appearance can be due to a variety of causes, including
  - infections,
  - inflammation,
  - malignancy,
  - metabolic or
  - mechanical factors.
- AKA:
  - Hypodense Lymph Nodes or Non-enhancing Lymph Nodes (referring to their appearance on imaging).
- Abbreviation:
  - LDL (Low-Density Lymphadenopathy)
- How does it appear on each relevant imaging modality:
  - Chest X-ray:
    - CXR does not have the contrast resolution to identify low density lymph nodes
  - CT Scan:
    - Parts:
      - Peripheral soft tissue density
      - Central low density.
    - Size:
      - Nodes usual
        
        greater than 1 cm in short axis
    - Shape:
      - Lymph nodes are generally round or oval.
    - Position:
      - Can be seen in the
        
        mediastinum
        
        hilar, or
        
        cervical regions.
    - Character: Low-density nodes often indicate
      - necrosis,
- Differential diagnosis:
  - Infection:
    - Tuberculosis (TB): Granulomatous inflammation with low-density necrosis in mediastinal lymph nodes, often with calcification.
    - Fungal infections (e.g., Histoplasmosis, Coccidioidomycosis): Granulomatous nodes with low-density centers due to necrosis.
    - Bacterial infections (e.g., pneumonia, abscesses): Nodes with central hypoattenuation, suggesting necrosis or pus.
  - Inflammation:
    - Sarcoidosis:
  - Neoplasm (Benign or Malignant):
    - Lymphoma: Lymph nodes with
      - central low-density areas due to necrosis
      - sometimes following treatment
    - Metastatic disease: Metastasis from lung cancer, esophageal cancer, or other tumors can cause low-density lymph nodes due to necrosis or fibrosis.
  - Metabolic:
    - Amyloidosis: Lymph nodes with low-density appearance due to amyloid protein deposition.
    - Gaucher’s disease: Enlarged lymph nodes with low-density areas from glucocerebroside accumulation.
  - Iatrogenic:
    - Post-radiation changes: Lymph nodes may become low-density due to necrosis or fibrosis following radiation therapy.
- Recommendations:
  - Next diagnostic steps:
    - Laboratory testing: Blood tests to evaluate for infections (e.g., CBC, tuberculin skin test), autoimmune markers, or cancer screening.

TCV Finding: Low-Density Lymphadenopathy in the Chest