Atypical CT manifestations of pulmonary sarcoidosis

Abstract

Sarcoidosis is a granulomatous disease of unknown etiology that affects different organs and tissues. Pulmonary, mediastinal, and intrathoracic lymph nodes involvement occur in about 90% of patients with sarcoidosis. Radiological manifestations of pulmonary sarcoidosis vary significantly. This article describes focal and reticulonodular changes, as well as consolidation zones and fibrotic changes. Isolated reticular changes due to thickening of intra-, and interlobular septa occur in approximately
50% of sarcoid patients. However, this CT pattern prevails only in 15–20% of patients. As a rule, in 80% of sarcoid patients changes in lung parenchyma are combined with intrathoracic lymphadenopathy. In the majority of cases, these changes are bilateral. In 10–13% of patients, foci 89–12 mm in diameter are detected. These foci have a homogenous structure and a well-defined outline. They locate mainly along costal and interlobar pleura, in interlobular septa, and may resemble metastases. In
2.4–4% of patients, these small foci, typical for sarcoidosis are absent, while the changes are presented by larger nodular masses (>2 cm in diameter) or by masses with fuzzy outlines. Often sarcoidosis mimicking interstitial pneumonia is manifested  by the ground-glass opacity of spot-like shape. Abnormalities are located in the upper lobes. This sign occurs in 16–83% of sarcoidotic patients, mainly at the onset of the disease. It usually combines with focal changes in the lungs and intrathoracic
lymphadenopathy. Cavitary forms of sarcoidosis are also described.

Conclusion. There are multiple pulmonary sarcoidosis manifestations on CT, and they vary a lot. The former allows suspecting the diagnosis, which is later confirmed clinically, morphologically, or by lab methods. Аtypical radiological forms of lung sarcoidosis often mimic other pulmonary diseases. These forms require invasive diagnostic methods including abdominal surgery.