TY - JOUR T1 - Ultra-rare cystic disease JF - European Respiratory Review JO - EUROPEAN RESPIRATORY REVIEW DO - 10.1183/16000617.0163-2019 VL - 29 IS - 157 SP - 190163 AU - Davide Elia AU - Olga Torre AU - Roberto Cassandro AU - Antonella Caminati AU - Sergio Harari Y1 - 2020/09/30 UR - http://err.ersjournals.com/content/29/157/190163.abstract N2 - Diffuse cystic lung diseases include a group of heterogeneous disorders characterised by the presence of cysts within the lung parenchyma, sometimes showing a characteristic computed tomography scan pattern that allows diagnosis. The pathogenetic mechanisms underlying cyst formation in the lung are still not clear and a number of hypotheses have been postulated according to the different aetiologies: ball-valve effect, ischaemic dilatation of small airways and alveoli related to infiltration and obstruction of small vessels and capillaries that supply the terminal bronchioles and connective tissue degradation by matrix metalloproteases. A wide number of lung cyst diseases have been classified into six diagnostic groups according to the aetiology: neoplastic, congenital/genetic, lymphoproliferative, infective, associated with interstitial lung diseases, and other causes. This article focuses on lymphangioleiomyomatosis, pulmonary Langerhans cell histiocytosis and Erdheim–Chester disease, Birt–Hogg–Dubé, follicular bronchiolitis and lymphocytic interstitial pneumonia, light-chain deposition disease and amyloidosis, congenital lung disease associated with aberrant lung development and growth, and cystic lung disease associated with neoplastic lesion. These cystic diseases are epidemiologically considered as ultra-rare conditions as they affect fewer than one individual per 50 000 or fewer than 20 individuals per million. Despite the rarity of this group of disorders, the increasing use of high-resolution computed tomography has improved the diagnostic yield, even in asymptomatic patients allowing prompt and correct therapy and management without the need for a biopsy.Diffuse cystic lung diseases show a characteristic CT scan pattern that often allows for diagnosis, even in asymptomatic patients, allowing prompt correct therapy and management without the needing of a biopsy https://bit.ly/2wIUKet ER -