Diffuse Cystic Lung Disease

Introduction

Diffuse cystic lung diseases (DCLDs) are a group of disorders with a broad differential that are de ned by the presence of multiple, thin-walled, airlled parenchymal lucencies, typically without other diffuse parenchymal changes. The most common DCLDs seen in pulmonary clinics are lymphangioleiomyomatosis (LAM), pulmonary Langerhans cell histiocytosis (PLCH), Sjogren cystic lung disease, and Birt-Hogg-Dubé (BHD) syndrome. However, the differential also includes metastatic neoplasms, smoking-related disorders, infections, congenital anomalies, hypersensitivity pneumonitis, and many other disorders. To remain focused on true (“primary”) DCLDs, we will not discuss forms of thin-walled cystic change that can accompany diseases in which interstitial lung disease or other parenchymal change is present, such as in sarcoidosis or idiopathic pulmonarybrosis.

The most common presentations of DCLDs are chronic dyspnea on exertion, pneumothorax, or incidental discovery of cystic changes on a HRCT. As with all diseases, the rst step in establishing the correct diagnosis is a detailed history and physical examination. Classical ndings are outlined in Table 20.1.

High-resolution computed tomography (HRCT) scanning can substantially narrow the differential, and in some cases can provide a diagnosis. For HRCT to be useful to the physician, it is essential to understand the radiographic de nition of a cyst, and to be able to distinguish it from other structures, such as emphysematous air space dilation, cavities,

F. X. McCormack (*) · B. M. Shaw

Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA

e-mail: frank.mccormack@uc.edu; mccormfx@ucmail.uc.edu; shawbw@ucmail.uc.edu

blebs, bullae, and pneumatoceles (Table 20.2). Review of the HRCT by a pulmonary radiologist familiar with the DCLDs is critical as the radiographic characteristics of cysts can be diagnostically useful (Table 20.3).

Table 20.1  History and gender predilection of common DCLDs

Disease History of present illness associations Gender predilection

LAM lymphangioleiomyomatosis, PLCH pulmonary Langerhans cell histiocytosis, BHD Birt-Hogg-Dubé, LIP lymphocytic interstitial pneumonia, FB follicular bronchiolitis, AML angiomyolipoma, HIV human immunode ciency virus, EBV Epstein-Barr virus

Table 20.2  Radiographic de nitions