From the Guidelines
The patient should undergo a PET-CT scan as soon as possible to evaluate the metabolic activity of the multiple pulmonary nodules and mediastinal lymphadenopathy, as this will help determine the likelihood of malignancy and guide further management. The chest X-ray findings in this 37-year-old male patient are concerning for possible metastatic disease or primary lung cancer. According to the study by 1, FDG PET/CT imaging is recommended in young male subjects with incidental enlarged mediastinal lymph nodes, as it can help identify malignant lesions. The study also notes that lymph nodes > 1 cm in short axis have been described in association with numerous other diseases, including pneumonia and other thoracic infections, congestive heart failure, granulomatous diseases such as sarcoidosis, and diffuse lung diseases.
Following the PET-CT, a tissue biopsy of the most accessible and metabolically active lesion (likely the 1 cm right upper lobe nodule) should be performed for definitive diagnosis. The study by 1 notes that FDG-PET whole body has a rating of 3, indicating that it is usually not appropriate as a standalone diagnostic tool, but it can be useful in conjunction with other imaging modalities and clinical evaluation. The patient should be referred to a pulmonologist or oncologist for comprehensive evaluation and management planning. The presence of innumerable pulmonary nodules along with mediastinal lymphadenopathy is highly suspicious for malignancy, though infections like tuberculosis or fungal diseases and inflammatory conditions should also be considered in the differential diagnosis.
Some key points to consider in the management of this patient include:
- The size and texture of the mediastinal lymph nodes, as well as the presence of a fatty hilum and calcification, can help distinguish between benign and malignant lesions 1
- The clinical history and pulmonary findings are important in determining the management of lymph nodes 1
- The patient should be counseled about the findings and the importance of completing the recommended imaging and follow-up promptly, as early diagnosis can significantly impact treatment options and outcomes.
From the Research
Patient Findings
- The patient has innumerable scattered soft tissue density pulmonary nodularity, with the largest nodule in the right upper lobe measuring 1 cm.
- Middle mediastinal lymphadenopathy is present.
- No acute cardiopulmonary pathology is otherwise identified.
Recommendation for PET CT
- PET CT can be useful to establish metabolic activity in the patient's pulmonary nodules and mediastinal lymphadenopathy 2, 3, 4, 5.
- The use of PET CT in differentiating benign from malignant solitary pulmonary nodules has been shown to be accurate, with a SUVmax value of 4 having the best sensitivity and specificity 2.
- In the context of mediastinal lymphadenopathy, PET CT can help differentiate infectious/inflammatory from malignant causes, with increased SUV, short-axis diameter, long-axis diameter, and axial short to long diameter ratios being accurate parameters 4.
- The optimal SUVmax cut-off value for determining mediastinal-hilar lymph node metastasis is still a matter of debate, with some studies suggesting a value of 2.5 5 and others proposing a higher value of 6.3 5.
Diagnostic Accuracy of PET CT
- The diagnostic accuracy of PET CT in mediastinal staging of patients with suspected resectable non-small cell lung cancer has been shown to be insufficient to allow management based on PET CT alone 3.
- The sensitivity and specificity of PET CT in detecting malignant mediastinal lymph nodes vary depending on the criteria used for test positivity, with a summary sensitivity of 77.4% and specificity of 90.1% for the "Activity > background" criterion 3.
- The use of PET CT in combination with other diagnostic modalities, such as endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA), can improve diagnostic accuracy 4, 5.