What are the best diagnostic tests to run for suspected lymphoma or lung cancer?

Diagnostic Tests for Suspected Lymphoma or Lung Cancer

For suspected lung cancer, tissue diagnosis should be obtained by the least invasive method appropriate for the lesion location, with bronchoscopy recommended for central lesions and transthoracic needle aspiration (TTNA) for peripheral lesions. 1

Lung Cancer Diagnostic Approach

Initial Evaluation

• Chest radiography as first test for suspected lung cancer
• Followed by chest CT with contrast for all patients with suspected lung cancer 2

Diagnostic Testing Based on Lesion Location

Central Lesions

• Bronchoscopy is recommended (Grade 1B) 1
  • High sensitivity for endobronchial disease
  • Should include biopsy, brushing, washing, and transbronchial needle aspiration (TBNA) as appropriate
  • If non-diagnostic but suspicion remains, further testing should be performed

Peripheral Lesions

• Transthoracic needle aspiration (TTNA) is recommended (Grade 1B) 1
  • Higher diagnostic yield than bronchoscopy for peripheral lesions
  • Higher risk of pneumothorax than bronchoscopic methods
• Alternative options for peripheral lesions:
  • Radial EBUS (endobronchial ultrasound) as an adjunct imaging modality (Grade 1C) 1
  • Electromagnetic navigation bronchoscopy if available (Grade 1C) 1

Special Circumstances

Extensive Mediastinal Involvement

• Diagnosis should be established by the least invasive and safest method 1:
  • Bronchoscopy with TBNA
  • Endobronchial ultrasound-guided needle aspiration (EBUS-NA)
  • Endoscopic ultrasound-guided needle aspiration (EUS-NA)
  • TTNA
  • Mediastinoscopy

Pleural Effusion

• Ultrasound-guided thoracentesis is recommended (Grade 1C) 1
  • If pleural fluid cytology is negative, proceed to pleural biopsy
  • Options include image-guided pleural biopsy or thoracoscopy
  • Consider a second thoracentesis before biopsy if first is negative

Lymphoma Diagnostic Approach

Imaging Studies

• PET/CT is the preferred imaging modality for lymphoma diagnosis and staging 3, 4
  • Higher diagnostic yield (4.9%) compared to body CT (2.5%) for detecting systemic involvement 4
  • Particularly valuable for extranodal disease detection
  • Sensitivity depends on lymphoma subtype and location 5

Tissue Diagnosis

• Definitive diagnosis requires tissue sampling from the most accessible site
• Excisional biopsy of lymph nodes is preferred when possible

Importance of Adequate Tissue Sampling

• Obtain sufficient tissue to:
  • Accurately define histologic type
  • Perform molecular analysis when applicable (Grade 1B) 1
  • Characterize non-small cell lung cancers for targeted therapy

Pitfalls to Avoid

• Not ruling out cancer in patients with hemoptysis and normal chest radiography
• Ignoring recurrent pneumonias in the same location
• Not confirming histologically suggestive metastatic findings 2
• Failing to obtain adequate tissue for molecular characterization of lung cancer

Radiation Exposure Considerations

• Mean effective dose from CT and PET/CT during treatment and surveillance periods can be significant
• However, theoretical risks of radiation-induced cancer should not be a major consideration in necessary diagnostic imaging 6

Remember that diagnosis and staging should be performed simultaneously rather than sequentially, using a systematic approach based on the clinical presentation and suspected diagnosis.