Case 5
History
15-year-old female with recurrent pulmonary infection with fever and cough.
PA chest radiograph shows a right lower lobe mass
containing multiple air fluid levels.
Chest CT confirms a right lower lobe mass containing
multiple air fluid levels.
Diagnosis
Congenital Adenomatoid Malformation.
Findings
Congenital adenomatoid malformation consists of an intralobar mass of disorganized pulmonary tissue that can exist with or without gross cyst formation. When present, the cysts can usually be shown to communicate with normal airways. Vascularization is via the pulmonary circulation. The etiology and pathogenesis is unknown. This anomaly is considered by some to represent hamartoma, whereas others feel that it results from localized arrested development of the fetal bronchial tree. The lesion may be classified into three distinct morphologic types:
- Type I, or cystic form, consists of one or more large airspaces. This is the most common type.
- Type II, or the intermediate form, is composed of numerous cysts measuring 1 - 10mm and is lined by epithelium.
- Type III, or the solid form, is the least common and is composed of solid masses of tissue without gross cyst formation.
Radiographically, the volume of the affected lung varies considerably from case to case. The lesion most commonly presents as a mass composed of numerous air-containing cysts scattered irregularly through tissue of unit density. Clinically, these patients can present with respiratory distress in the neonatal period. Pulmonary infection in older children can occur.
