Pulmonary Cystic Lesions in Multislice Computed Tomography: A Stepwise Diagnostic Approach Based on Radiological and Clinical Findings

Background: Lung cysts are commonly seen on computed tomography (CT), and cystic lung diseases show a wide disease spectrum. Correct diagnosis of cystic lung diseases is a chal-lenge for radiologists. Aim of Study: To evaluate the role of multislice and high resolution CT in the diagnosis, differentiation and detection of causes of pulmonary cystic lesions. Patients and Methods: This study involved 60 adult pa-tients presented by different chest manifestations diagnosed as having pulmonary cystic lesions by multislice CT (MSCT) or high resolution CT (HRCT). Detailed history was taken, thor-ough clinical examination and different laboratory tests were considered. The cystswere evaluated for the following: Site, size, number and content. Results: Females were slightly predominant compared to males accounting for 70%, smokers represented the majority of the included patients accounting for 65%. The distribution of the cysts was predominantly bilateral (97%). Most of the cases showed homogenous distribution of the cysts among all lobes (65%). Round shape was the commonest reported shape in 36 (60.0%) patients. Additional findings in the background of CT scan showed that 30 (50%) patients had nodules, 24 (40%) patients had ground glass opacities, 24 (40%) patients had interstitial/or septal thickening, 6 (10%) patients had fibrot-ic changes, 6 (10%) patients had a pneumothorax and 6 (10%) patients had associated honeycombing pattern. No associated CT findings other than cysts were seen in 9 cases. In the current study, the commonest diagnosis was LAM in 21 (35%) patients, followed by LCH in 18 (30%) patients, interstitial pneumonia in 13 (21.6%) patients, 6 (10%) cases with HP, two cases with genetic disease Birt-Hogg-Dubé syndrome. Conclusions: Multislice computed tomography has an established role in assessment of pulmonary cystic lesions. Recommended step wise approach including exclusion of cyst mimickers first, then considering the clinical data and analyzing the radiographic characters of the cysts, all together can be used for differentiation and detection of causes of pulmonary cystic lesions.