Diagnostic Investigations for Sarcoidosis
Core Diagnostic Approach
- The American Thoracic Society recommends assessing for highly probable clinical features including Löfgren's syndrome, lupus pernio, uveitis, optic neuritis, and erythema nodosum in patients with suspected sarcoidosis 2, 3
- The American College of Chest Physicians recommends performing baseline serum calcium testing to screen for abnormal calcium metabolism (strong recommendation) 1
- Baseline serum creatinine and alkaline phosphatase should be obtained to screen for renal and hepatic involvement (conditional recommendations) 1
- A baseline ECG should be conducted to screen for possible cardiac involvement in patients with extracardiac sarcoidosis 1
Imaging Studies
- Chest radiography and CT are essential first-line investigations, with bilateral hilar adenopathy and perilymphatic nodules being highly supportive of sarcoidosis 2, 4
- Bilateral hilar adenopathy on CXR, CT, or PET is a highly probable feature of sarcoidosis 3
- Perilymphatic nodules on chest CT are a highly probable feature of sarcoidosis 3
Tissue Sampling
- Tissue biopsy showing nonnecrotizing granulomatous inflammation is crucial for diagnosis 1
- In patients with high clinical suspicion, lymph node sampling may be avoided (conditional recommendation) 1
Bronchoalveolar Lavage (BAL) Analysis
- BAL can be useful for excluding infections or malignancy and identifying cellular patterns suggestive of sarcoidosis 5
- BAL lymphocytosis or elevated CD4:CD8 ratio is considered a probable feature supporting sarcoidosis diagnosis 3, 4
Exclusion of Alternative Diagnoses
- Infectious causes of granulomatous inflammation, such as tuberculosis and fungal infections, should be ruled out 3
- Malignancy-associated sarcoid-like reactions should be excluded, especially in patients with suspected or known neoplasms 4
- Other granulomatous disorders, such as chronic beryllium disease, hypersensitivity pneumonitis, ANCA-associated vasculitides, and IgG4-related disease, should be considered 4, 5