CHAPTER 1 Cystic lesions of the lung in children: classification and controversies J.T. Stocker*, A.N. Husain # *Dept of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, and # Dept of Pathology, University of Chicago, Chicago, IL, USA. Correspondence: J.T. Stocker, Dept of Pathology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814-4799, USA. Fax: 1 3012951640 E-mail: jstocker @usuhs.mil Cystic diseases of the lung cover a broad spectrum of lesions, ranging from clearly congenital lesions to lesions acquired through a variety of aetiologies (infection, barotrauma, neoplasia, infarction, etc. table 1). Although not truly cystic or even pulmonary, a number of both congenital and acquired diseases may be confused both clinically and radiographically with the morphological cystic diseases of the lung. (table 2). A selected few are discussed briefly later in the present chapter. The organisation and classification of congenital cystic lung diseases began in the mid 1990s with the report by Ch’in and Tang [1] describing a malformation of the lung in an infant born to a mother with polyhydramnios. The solid-appearing lung lesion was composed of gland-like alveoli, all lined with cuboidal epithelium. They called the abnormality congenital adenomatoid malformation. Over the following 30 yrs, various authors described other malformations of the lobes of the lung, some of which resembled the lesion described by Ch’in and Tang [1] and others of which were cystic and composed of bronchioles and other acinar structures in various combinations. This collection of lesions became known as congenital cystic adenomatoid malformation (CCAM). Table 1. – Cystic lesions CPAM type 1 CPAM type 2 CPAM type 4 Peripheral cysts Following infarction Down’s syndrome Associated with idiopathic spontaneous pneumothorax Intralobar sequestration Extralobar sequestration with CPAM type 2 Interstitial pulmonary emphysema Acute Persistent Congenital pulmonary lymphangiectasia Pleuropulmonary blastoma Type I (purely cystic) Type II (cystic/solid) Infectious/parasitic cysts Necrotising pneumonia with abscess formation Hydatid cysts CPAM: congenital pulmonary airway malformation. Eur Respir Mon, 2007, 39, 1–20. Printed in UK - all rights reserved. Copyright ERS Journals Ltd 2007 European Respiratory Monograph ISSN 1025-448x. 1