Cystic lung in sarcoidosis: a rare condition

Sarcoidosis can manifest with a range of atypical findings on high resolution computed tomography (HRCT). Cysts are a very rare component of lung sarcoidosis. The aim of our study was to describe a series of patients with cystic sarcoidosis and to delineate their clinical-radiological characteristics and progression. In this retrospective, bicentric study we recruited patients affected by sarcoidosis with lung cystic lesions at HRCT from 1st January 2007 to 31st October 2023. 12 patients (6 males, mean age 50 ± 12 years) were identified (prevalence: 1.9%; 95%Confidence Interval: 0.8% - 2.9%). Four patients were black, and six patients were ex-smokers. All patients presented multiple cystic lesions with a bilateral distribution in 10/12, the presence of micronodules and nodules in 11/12 patients and fibrotic lesions in 3/12. Lung function tests were normal in 7 patients, while an obstructive syndrome was detected in 3 patients, a restrictive syndrome in one, and a coexistence of both in one. Ten patients had a DLCO<80% predicted (mean ± SD: 64.1 ± 14.1%). During follow-up (mean ± SD: 8.7 ± 5.9 years), an increase of the number of cystic was observed in 4 patients. Patients who experienced an increase in the number of cysts were those who, at diagnosis, had a low value of DLCO (%predicted) (p=0.015) and evidence of nodules (p=0.038) and fibrotic lesions (p=0.030). At the end of follow-up all patients were alive. Only 3 patients (25.0%) experienced a decline of FVC > 10% of predict while 3 patients (25.0%) experienced a decline of DLCO > 10% of predict. Two patients developed lung infection (one bacterial pneumonia, one Pneumocystis jiroveci infection). In conclusion, cystic lung lesions are rare in patients with sarcoidosis and do not influence long term prognosis.