Pulmonary Sarcoidosis: Typical and Atypical Manifestations at High-Resolution CT with Pathologic Correlation

Abstract

Sarcoidosis is a multisystem disorder that is characterized by noncaseous epithelioid cell granulomas, which may affect almost any organ. Thoracic involvement is common and accounts for most of the morbidity and mortality associated with the disease. Thoracic radiologic abnormalities are seen at some stage in approximately 90% of patients with sarcoidosis, and an estimated 20% develop chronic lung disease leading to pulmonary fibrosis. Although chest radiography is often the first diagnostic imaging study in patients with pulmonary involvement, computed tomography (CT) is more sensitive for the detection of adenopathy and subtle parenchymal disease. Pulmonary sarcoidosis may manifest with various radiologic patterns: Bilateral hilar lymph node enlargement is the most common finding, followed by interstitial lung disease. At high-resolution CT, the most typical findings of pulmonary involvement are micronodules with a perilymphatic distribution, fibrotic changes, and bilateral perihilar opacities. Atypical manifestations, such as masslike or alveolar opacities, honeycomb-like cysts, miliary opacities, mosaic attenuation, tracheobronchial involvement, and pleural disease, and complications such as aspergillomas, also may be seen. To achieve a timely diagnosis and help reduce associated morbidity and mortality, it is essential to recognize both the typical and the atypical radiologic manifestations of the disease, take note of features that may be suggestive of diseases other than sarcoidosis, and correlate imaging features with pathologic findings to help narrow the differential diagnosis.

Relationship between radiologic patterns, pulmonary function values and bronchoalveolar lavage fluid cells in newly diagnosed sarcoidosis

“…Airspace consolidation in sarcoidosis reflects the confluence of numerous micronodules that compress the surrounding alveoli or encroach on the alveolar spaces (6). The pathological significance of ground glass opacity can result from the confluence of multiple micronodular granulomas and/or fibrotic lesions (39).…”

“…The presence of typical [i.e., hilar, mediastinal (right paratracheal), bilateral, symmetric, ≥15 mm in diameter] and atypical (i.e., unilateral, isolated, anterior and posterior mediastinal) localization of lymph nodes and the occurrence of lymph node calcification were determined (6).…”

“…Radiographic staging was developed before the introduction of computed tomography (CT). CT, especially high-resolution CT (HRCT), is far more sensitive than chest radiography in discerning subtle parenchymal abnormalities in the early stages of the disease (6). Chest CT allows for the identification of pathological changes not seen in conventional chest radiographs.…”

“…Chest CT allows for the identification of pathological changes not seen in conventional chest radiographs. CT, especially HRCT, may be particularly useful for distinguishing active inflammation from irreversible fibrosis in patients with stage II or stage III sarcoidosis (6).…”

Chest Computed Tomography-Based Scoring of Thoracic Sarcoidosis: Inter-rater Reliability of CT Abnormalities

“…A multitude of abnormalities can be detected [1][2][3][4], but little is known about inter-rater agreement. There appears to be good reported agreement between raters in scoring a limited number of abnormal CT findings in sarcoidosis with kappa values ranging from 0.81 to 0.89.…”