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Obstetrics » Obstetrics 2nd And 3rd Trimester
Fetal bronchopulmonary sequestration with cystic adenomatoid malformation
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Author(s) :
Wesley Lee, MD
Presentation This is a 30 year old female who presented to the ultrasound unit at a gestational age of 18.5 menstrual weeks with diamniotic, dichorionic twins. Her past history was remarkable for a prior fetus with Turner's syndrome. The initial study indication was for fetal growth evaluation and the anatomic survey for both twins was unremarkable. She had a repeat scan for growth evaluation at 25.3 menstrual weeks. At that time, one of the twins demonstrated bilateral pleural effusions (Figures 1 and 2). The right lung appeared to be replaced by an echogenic complex mass that measured 4.2 x 4.4 x 2.5 cm. Several fluid-filled cysts (about 2-3 mm size) were present throughout the mass. Doppler ultrasonography did not suggest unusual vascularity.
Caption: Fetal chest - sagittal view
Description: Echogenic lung mass (arrow) is surrounded by pleural effusion.
Caption: Fetal Chest - axial View
Description: Echogenic lung mass is surrounded by bilateral pleural effusions.
Caption: Postnatal Radiograph
Description: Lung mass (dark area) compresses the fetal heart towards the left side.
Caption: Autopsy specimen
Description: Cross section demonstrates macrocysts that suggest cystic adenomatoid malformation. Note the aberrant blood supply to the aorta (arrow).
Caption: Pathology specimen - heart and lungs
Description: The light tan tissue is the extralobar bronchopulmonary sequestration with aberrant arterial blood supply(arrow).
Differential Diagnosis The differential diagnosis for this chest mass includes cystic adenomatoid malformation, pulmonary sequestration. bronchogenic or enteric cyst, bronchial atresia, mediastinal cystic hygroma, and neuroblastoma (1).
Final Diagnosis The final diagnosis was a bronchopulmonary sequestration with areas containing cystic adenomatoid malformation.
Discussion The most common etiologies for a fetal chest mass with hydrops is cystic adenomatoid malformation, pulmonary sequestration, and congenital diaphragmatic hernia. King and co-workers (1) presented a nice review of echogenic lung lesions by prenatal sonography. The prenatal diagnosis was correct in 13 of 17 fetuses with echogenic lung masses. Cystic adenomatoid malformation has been traditionally divided into three different types based on the presence of cysts (2). Type I consists mainly of large cysts, Type II is mixed, and Type III involves the presence of microcysts. In our case, the presence of cystic structures within this mass strongly suggested a cystic adenomatoid malformation. This abnormality can also be confused with bronchopulmonary sequestration where a part of the lung has become disconnected with the bronchial tree. These lesions can occur within (intralobar) or outside (extralobar) the main lung parenchyma. Congenital anomalies, such as diaphragmatic hernia, cardiac defects, and gastric communications, are more commonly found (15-60%) with extralobar sequestration (3). In the current case, we were unable to document an aberrant vessel by color Doppler sonography. An example of a systemic vascular supply is demonstrated in another fetus with pulmonary sequestration (Figure 6). Cystic adenomatoid malformation and bronchopulmonary sequestration are traditionally considered to have distinctive embryology, histologic characteristics, and natural history. However, Cass and co-workers (4) have described six fetuses who were diagnosed with fetal chest masses between 19-30 menstrual weeks. All six were thought to have the sonographic appearance of cystic adenomatoid malformation because an aberrant systemic vessel was not identified. After delivery, all 6 lesions were confirmed to have an aberrant systemic vessel directly from the aorta. The surgical findings indicated an bronchopulmonary sequestration of the extralobar variety in 1 case and intralobar type in the others. Nonetheless, all 6 lesions had histologic evidence of cystic adenomatoid malformation. These "hybrid" cases suggest a similar embryological origin for both types of pulmonary lesions and underscores the difficulty with trying to differentiate between the two lesions by prenatal sonography.
Case References 1. King SJ, Pilling DW, Walkinshaw S. Fetal echogenic lung lesions: prenatal ultrasound diagnosis and outcome. Pediatr Radiol 1995;25:208-10. 
2. Stocker JT, Madewell JE, Drake RM. Congenital cystic adenomatoid malformation of the lung. Hum Pathol 1977; 8:155-71. 
3. Savic B, Birtel FJ, Tholen W, Funke HD, Knoche R. Lung sequestration: report of seven cases and review of 540 published cases. Thorax 1979; 34:96-101. 
4. Cass DL, Crombleholme TM, Howell LJ, Stafford PW, Ruchelli ED, Adzick NS. Cystic lung lesions with systemic arterial blood supply: a hybrid of congenital cystic adenomatoid malformation and bronchopulmonary sequestration. J Pediatr Surg 1997;32:986-90.
Follow Up The patient developed preterm labor and delivered twins. The fetus with the lung mass and pleural effusions expired.
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