From the Guidelines
Granulomas are typically not directly visible on chest X-rays for sarcoidosis, but rather their presence is inferred by the presence of bilateral hilar lymphadenopathy or other radiographic findings. The diagnosis of sarcoidosis is based on the presence of a compatible clinical scenario, radiographic findings, and histologic confirmation of noncaseating granulomatous inflammation 1. While chest X-rays can show signs suggestive of granulomatous inflammation, such as bilateral hilar lymphadenopathy, reticular opacities, or nodules, they have limitations in detecting smaller granulomas, and some patients with sarcoidosis may have normal chest X-rays despite having the disease. For accurate diagnosis, techniques like endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) are recommended, especially in patients with suspected sarcoidosis with mediastinal and/or hilar adenopathy, due to their high pooled diagnostic accuracy of 79.1% 1. Some key points to consider in the diagnosis of sarcoidosis include:
- The presence of noncaseating granulomatous inflammation on histologic examination
- The use of EBUS-TBNA as a minimally invasive modality for lymph node staging and diagnosis
- The importance of combining EBUS-TBNA with other bronchoscopic techniques, such as transbronchial lung biopsy (TBLB) and endobronchial biopsy (EBB), to enhance diagnostic yield
- The limitations of chest X-rays in detecting smaller granulomas and the potential for normal chest X-rays in patients with sarcoidosis.
From the Research
Granulomas on Chest X-ray for Sarcoidosis
- Granulomas are a characteristic feature of sarcoidosis, but they are not directly visible on chest X-ray 2, 3, 4, 5, 6.
- Chest X-ray can show signs of sarcoidosis, such as hilar lymphadenopathy and pulmonary infiltrates, but it is not sensitive enough to detect granulomas 2, 3, 4.
- High-resolution computed tomography (HRCT) is more sensitive than chest X-ray for detecting granulomas and other signs of sarcoidosis 3, 5, 6.
- HRCT can show characteristic features of sarcoidosis, such as micronodules with a perilymphatic distribution, fibrotic changes, and bilateral perihilar opacities 3, 5, 6.
Limitations of Chest X-ray
- Chest X-ray has a low sensitivity for detecting sarcoidosis, especially in early stages of the disease 2, 4.
- Chest X-ray can be normal in up to 30% of patients with sarcoidosis, even if they have granulomas on HRCT 2.
- CT imaging is more superior than CXR in the early diagnosis and staging of sarcoidosis 2.
Alternative Imaging Modalities
- HRCT is the preferred imaging modality for detecting granulomas and other signs of sarcoidosis 3, 5, 6.
- Cardiac/thorax MRI can also be used as an initial screening test for sarcoidosis, especially in patients with cardiac symptoms 4.
- CT chest has the highest specificity among imaging modalities for detecting sarcoidosis 4.