Atypical HRCT manifestations of pulmonary sarcoidosis

To present our experience of cases of pulmonary sarcoidosis with atypical HRCT patterns found during 2016 focusing on the differential diagnosis to contribute to the difficult role of the radiologist in the disease identification and to help the clinicians to reach the diagnosis.

The HRCT examinations of 47 patients with sarcoidosis were studied retrospectively. All patients had a histopathological confirm of the disease. 29 (61.7%) show a typical pulmonary pattern and 18 (38.3%) an atypical pattern. The latter were evaluated by three experienced radiologists dedicated to thoracic disease to radiologically define the predominant pattern of presentation.

In the 18 patients (38.3%) with atypical sarcoidosis, the following parenchymal patterns were observed: four patients (22.2%) had interstitial fibrotic alterations, three patients (16.6%) with reticular pattern with inter-intralobular septal thickening, two patients (11.1%) with small-airway involvement with mosaic oligoemia, two patients (11.1%) with pleural involvement (pneumothorax and pleural plaques), one patient (5.5%) with fibrocystic changes, 1 (5.5%) with halo-sign, 1 (5.5%) with diffuse bilateral ground-glass opacities, and 1 (5.5%) with isolated lung mass; in addition, three patients (16.6%) with atypical lymph node pattern were also found.

The atypical pulmonary alterations found in CT examination can be confused with other lung diseases and they are always a challenge even for the most experienced radiologist. In our experience, cases with atypical pulmonary sarcoidosis patterns evaluated in the study are consistent with similar cases described in the literature, both in lymph node and atypical parenchymal involvement. All the atypical characteristics of the work should alert the radiologist to consider sarcoidosis among the possible differential diagnoses, always correlating the results of the computed tomography examination with appropriate clinical-laboratory evaluations.