CASE 9442 Published on 16.09.2011

Congenital pulmonary airway malformation type II with pulmonary sequestration (hybrid lesion)

Section

Paediatric radiology

Case Type

Clinical Cases

Authors

Cristina Pérez López, Ivana Carcacía Hermilla, Javier Pérez-Cid Rebolleda, Purificación Pardo Rojas, Manuel Vázquez Rodríguez.

Patient

1 days, female

Categories
Area of Interest Thorax ; Technique Ultrasound, Conventional radiography, CT, CT-Angiography
Clinical History
1-day-old female neonate presented with mild tachypnoea after birth. At routine prenatal ultrasound, the fetus manifested an intrapulmonary mass. Her APGAR scores were normal at 1 and 5 minutes (10, 10) after spontaneous delivery. The infant was born at 40+4 weeks gestation. Bird weight was 3,340 Kg.
Imaging Findings
Prenatal routine ultrasound (US), obtained at 20 weeks gestational age, demonstrated the presence of a hyperechoic mass with cystic areas in lower lobe of the right lung.
Frontal chest postnatal radiograph obtained at 1 day of life showed small, hazy cystic radiolucent areas in the right lower lobe. No mass effect was observed.
Because of the progressive respiratory distress and infection a basal computed tomography (CT) was performed when she was 7-month-old. The CT revealed a unilateral air-filled multicystic lesion in the lower lobe of the right lung. All the cysts are small (< 2cm) with thin wall.
CT following intravenous contrast material administration was performed one month later in order to planning resection. The CT showed a feeding artery arising from the subphrenic abdominal aorta.
Discussion
Congenital pulmonary airway malformation (CPAM) is a lung mass that results from a proliferation of disorganised pulmonary tissue replacing normal alveoli. Its prevalence is 1 per 25000-35000 pregnancies [1].
Most CPAMs derive their blood supply from the pulmonary artery. Systemic arterial supply suggests pulmonary sequestration (PS).
Hybrid lesions (HLs) combine histologic and imaging features of CPAM and PS suggesting that these two entities have a common embryologic origin [2]. Arterial supply is typically from descending aorta (20% below the hemidiaphragm).
Stocker has divided CPAM into five types according to the location or stage of development of involvement with the tracheobronchial tree [3].
Type 2 CPAM (15%-20% of all CPAMs) is characterised by small cysts (<2cm) lined by cuboidal or columnar epithelial cells [2]. It has a strong association with other congenital anomalies. SP are reported to exist with type 2 CPAM in up to 50% of cases [4].
If not recognised antenatally, HLs usually manifest during the neonatal period as respiratory distress [1] or recurrent infections. HLs can also be incidentally detected on chest radiography in asymptomatic older paediatric patients.
At prenatal US, type 2 CPAM can be identified as an echogenic mass with multiple small cysts [5]. Fetal MR imaging may aid in its characterisation [2].
Radiography is the initial imaging study in postnatal diagnosis, demonstrating a unilobar mass with small air-filled cystic areas. It may cause mass effect. Some lesions can be subtle and may not be detected at radiography [5].
CT defines the location, extent and anatomical relationships for presurgical planning and CT-angiography can demonstrate the presence of any systemic arterial supply.

If prenatal detected lesions are associated with complication, fetal interventions should be considered.
Postnatal symptomatic HLs should be managed with surgical resection. If the patient is asymptomatic, management can be controversial because there is an increased risk of recurrent infections and malignant transformation [3].
Prognosis depends on the degree of development of the adjacent lung, the size of the lesion and the presence of other congenital anomalies [1], which can be demonstrated on CT.
So, although congenital lung anomalies can present as unique entities, CPAM and PS can coexist and manifest as a hybrid lesion. CT with IV contrast is utilised for further characterisation of lesions for presurgical planning. The radiologist needs to be alert to search for an aberrant systemic arterial vessel when imaging suspected cases of CPAM [4]. Detailed knowledge of the presence and course of anomalous vessels is essential to surgeons in planning resection.
Differential Diagnosis List
Congenital pulmonary airway malformation (CPAM) type II with pulmonary sequestration.
Congenital diaphragmatic hernia
Bronchial atresia
Pneumonia
Broncogenic cyst
Congenital lobar emphysema
Final Diagnosis
Congenital pulmonary airway malformation (CPAM) type II with pulmonary sequestration.
Case information
URL: https://www.eurorad.org/case/9442
DOI: 10.1594/EURORAD/CASE.9442
ISSN: 1563-4086