Presence of macronodules in thoracic sarcoidosis: prevalence and computed tomographic findings

Aim: To assess the prevalence and radiological findings of macronodules in patients with thoracic sarcoidosis. Materials and methods: Data was collected regarding 226 patients with pathologically proven thoracic sarcoidosis. Among them, macronodules defined as well-defined nodules greater than 5 mm were found in 58 patients. The macronodules were evaluated by their number, size, margin, shape, lobar location, distance from the pleura, and temporal change. Patients were classified into two groups, patients with macronodules (n = 58) and without macronodules (n = 168). The level of serum angiotensin-converting enzyme (ACE), systemic involvement, and the maximum standardized uptake value (maxSUV) on ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) in both groups were then compared. Results: A total of 216 macronodules were identified in 58 patients. The mean number of macronodules per patient was 3.3, and the mean size was 6.3 mm. Most of the macronodules were located in lower lobes (63.4%) and showed round-to-ovoid (95.8%) shape. The mean distance from the pleura was 5 mm. In 76% of the 63 nodules that were followed using CT scanning, any interval changes in size was also accompanied by the same change in mediastinal lymphadenopathy. On comparison of the two groups, the presence of lymphadenopathy, parenchymal involvement, and the maxSUV of thoracic lymphadenopathy were shown to be statistically different. Conclusion: Well-defined macronodules greater than 5 mm were not uncommonly seen in patients with thoracic sarcoidosis. The macronodules are usually located in the lower lobes near the pleura, and the interval changes in mediastinal lymphadenopathy may be associated with similar changes in the size of nodules. -- Highlights: •Well-defined macronodules (>5 mm) are not uncommon findings in thoracic sarcoidosis. •The changes in thoracic lymphadenopathy may be associated with those in macronodules. •The radiologic characteristics of macronodules resemble the intrapulmonary lymph nodes. •Recognition of the macronodules will be beneficial to avoid misdiagnosis as metastasis