CASE 11306 Published on 06.10.2013

Absence of the left lung: agenesis, aplasia or hypoplasia?

Section

Chest imaging

Case Type

Clinical Cases

Authors

Rafailidis Vasileios, Theodoridis Triandafyllos, Liouliakis Christos, Gavriilidou Anna.

General Hospital of Katerini,
6 km Katerini-Arona
60100, Katerini, Greece;
Vizyis Vyzantos 24
54636 Thessaloniki, Greece;
Email:billraf@hotmail.com
Patient

72 years, female

Categories
Area of Interest Lung, Abdomen, Anatomy, Cardiac, Colon, Gastrointestinal tract, Arteries / Aorta, Computer applications ; Imaging Technique Conventional radiography, CT
Clinical History
A 72-year-old female patient had a severe pneumonia and she underwent thorough imaging. She suffered from frequent respiratory infections (usually not severe) but had never had any kind of accident.
Imaging Findings
The chest radiograph showed a radiopaque left hemithorax with righ shift of the mediastinum. (Fig 1)
Double-contrast barium enema demonstrated the presence of large part of the intestine inside the left hemithorax (Fig 2).
CT examination revealed complete occupation of the left hemithorax by abdominal organs. Namely, the left hemithorax contained the spleen, small and large intestine and a large quantity of mesenteric fat. The small and large intestine lied in the periphery of the thoracic cavity while its central part was occupied by mesenteric fat (Fig 3a, b, c). CT also revealed a hypoplastic left lung, the presence of left pulmonary artery and a blind-ended left main bronchus (Fig 3b). Finally, the CT examination demonstrated a defect in the left hemidiaphragm, which caused the intrathoracic displacement of the abdominal organs (Fig 3d). Multi-planar reconstructions (MPR) and Volume Rendering Techniques (VRT) were performed to better delineate the findings (Fig 4, 5).
Discussion
Schneider and Schwalbe classified pulmonary underdevelopment into three categories: agenesis, aplasia and hypoplasia [1]. Agenesis of the lung refers to the complete absence of lung parenchyma along with its bronchus and vasculature. Pulmonary aplasia represents the existence of a rudimentary blind-ended bronchus without lung parenchyma and pulmonary vasculature. Hypoplasia describes the existence of a hypoplastic bronchus with a hypoplastic lung tissue containing alveoli, airways and pulmonary vasculature [2].
Pulmonary hypoplasia (PH) is characterised by underdevelopment of the lung which is caused by any situation that limits the space of the thoracic cavity available for lung growth. The longer the underlying cause exists and the more intense it is, the more hypoplastic the lung will be. As in our case, a congenital diaphragmatic hernia is one of the most common causes of PH as the defect of the hemidiaphragm allows the abdominal organs to move into the thorax, thus compressing the developing lung. Other intrathoracic causes of lung hypoplasia include sequestration, mediastinal masses, complete absence of the diaphragm and a large pleural effusion. Other causes include decreased pulmonary blood supply and extrathoracic diseases like oligohydramnios [2, 3]. Pulmonary hypoplasia may also be primary with a very low frequency (0.8-1.6 per 10000 births) [4].
Clinical presentation of PH comprises early respiratory distress after birth, cyanosis, tachypnoea, hypoxia with hypercapnea and acidosis. PH can be complicated by pneumothorax or pulmonary hypertension.
Chest radiograph of a patient with PH will show decreased radiolucency in the affected lung (more often the right). The mediastinum may be displaced towards the affected side due to compensatory ventilation of the normal lung and in some cases congenital bronchiectasis can be seen. On lateral chest radiograph, hyperclarity may be seen behind the sternum due to herniation of the normal lung. Prenatal diagnosis with US is difficult but can be more easily done with MRI where the volume of the two lungs can be measured and the hypoplastic lung usually has lower signal intensity than normal [3, 5].
The majority of patients with PH die but there are also patients who survived and were diagnosed with imaging [4].
When surgery is planned, CT is the imaging modality of choice for preoperative planning as it describes better the anatomic extent of pathology [6].
Recent papers report that early fetoscopic tracheal occlusion increases the survival rate of infants with severe pulmonary hypoplasia and congenital diaphragmatic hernia [7].
Differential Diagnosis List
Pulmonary hypoplasia caused by a large congenital diaphragmatic hernia.
Cystic adenomatoid malformation
Pulmonary agenesis
Pulmonary aplasia
Pulmonary hypoplasia
Congenital diaphragmatic hernia
Final Diagnosis
Pulmonary hypoplasia caused by a large congenital diaphragmatic hernia.
Case information
URL: https://www.eurorad.org/case/11306
DOI: 10.1594/EURORAD/CASE.11306
ISSN: 1563-4086