Congenital Cystic Adenomatoid Malformation of the Lung: Clinicopathologic analysis of 22 cases

Oh, Young Lyun; Suh, Yeon Lim; Chi, Je G

Abstract

Congenital cystic adenomatoid malformation of the lung(CCAML) is a rare developmental anomaly characterized by an "adenomatoid" hyperplasia of terminal respiratory structures with formation of the cysts of varying sizes. CCAML is separated into three major types based on the gross and microscopic findings. We have analyzed 22 cases of CCAML, those consisted of 6 autopsy cases and 16 surgical specimens. Out of 22 cases, 5 cases were composed of large cysts(type I) and 9 cases had multiple small cysts(type II). Remaining one case revealed features of solid type(type III), and 7 cases were mixed form. There were 16 boys and 6 girls. All cases were below the age of 14 years. There was no clear-cut age difference between different types of CCAML. However, inflammation, fibrosis and pseudostratification of epithelium were often found in older age. All fetal autopsy cases of CCAML had hydrops fetalis and were associated with maternal hydramnios. One case of type III showed definite mucinogenic cells in the cysts unexpectedly, and one case of the mixed form(typeI+II+III) was found in a fetus of 22 weeks of gestational age. Above findings contradicted the classical description of the CCAML, and suggested that arbitrary classification into three types may not be the best way in understanding this condition.