White hemithorax in children

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1 DOI /s PICTORIAL ESSAY White hemithorax in children Javier Lucaya & Enrique F. Garcés-Iñigo & Pilar García-Peña & Joaquim Piqueras & Goya Enriquez Received: 28 July 2010 /Revised: 28 October 2010 /Accepted: 5 December 2010 # Springer-Verlag 2011 Abstract The aim of this pictorial review is to introduce the radiologist to the differential diagnosis of a white hemithorax in children, to provide significant information on the diagnostic work-up, and to promote radiation-free techniques whenever possible. There are many causes of white hemithorax in children and it can be due to a variety of chest disorders. In most cases, plain chest radiographs and ultrasound will suffice. However, additional information provided by, e.g., CT or MRI is sometimes required. Keywords Opaque hemithorax. White hemithorax. Lung collapse. Chest ultrasound Introduction The term white hemithorax is used to describe a radiopaque hemithorax at chest radiography, usually homogeneous in density, but sometimes with scattered areas of air or calcium. A white hemithorax is a common finding on chest radiographs in children and may be due to a variety of chest disorders. This essay reviews the possible diagnoses to be considered and suggests diagnostic imaging procedures for confirming the suspected diagnosis. Knowledge of the patient s age and clinical symptoms, and recognition of the position of the mediastinal structures are essential to establishing a complete differential diagnosis, and subsequently for reaching the correct diagnosis. J. Lucaya (*) : E. F. Garcés-Iñigo : P. García-Peña : J. Piqueras : G. Enriquez Department of Pediatric Radiology, Hospital Materno-Infantil de la Vall D Hebron, Barcelona, Spain xlucaya@gmail.com For educational purposes, the white hemithorax has been divided into groups according to age (neonatal or beyond) and mediastinal position. White hemithorax in the neonate With ipsilateral mediastinal displacement Lung agenesis, severe lung hypoplasia and lung collapse are the most common causes of a white hemithorax with volume loss in the neonate [1, 2]. In these entities, the involved hemithorax will be homogeneously white and the mediastinal structures shifted towards the abnormal side. Associated vertebral malformations favour a diagnosis of lung agenesis. Recent extubation and malpositioned endotracheal tube are common causes of unilateral lung atelectasis in the neonate [3] (Fig. 1). Thus, a review of previous films and careful evaluation of the position of the endotracheal tube may be the key to correct diagnosis. With contralateral mediastinal displacement Unilateral white hemithorax with increased volume of the affected side causing contralateral mediastinal displacement may be due to pleural effusion, which, in the neonate, is almost always chylous (Fig. 2) [4, 5]. Volume-occupying congenital malformations, such as congenital diaphragmatic hernia, cystic adenomatoid malformation, pulmonary sequestration (Fig. 3) or fluid-filled lobar emphysema, may also produce a radiopaque hemithorax with contralateral mediastinal shift [1, 2, 5]. However, in these cases, the density of the involved hemithorax will usually be heterogeneous due either to aerated lung around, or air-filled structures within, the lesion.

2 Fig. 1 A 23-day-old premature infant with right atelectasis simulating lung agenesis. The child had recently been extubated and developed severe respiratory distress. a On the acute chest radiograph, the right hemithorax is homogeneously white and the mediastinal structures are shifted ipsilaterally. b Repeat radiograph following physiotherapy is normal Beyond the neonatal period With ipsilateral mediastinal displacement Lung agenesis, severe hypoplasia or lung collapse may also be considered beyond the neonatal period. While the former two cause few symptoms, the latter produces severe respiratory symptoms regardless of aetiology (Fig. 4). Again, associated vertebral malformations favour the diagnosis of unilateral lung agenesis. Unlike in the neonate, the differential diagnosis of lung collapse is extensive and includes bronchial foreign body aspiration, bronchial mucous plugs, endobronchial tumours and extrinsic bronchial compression [6]. Most patients with mucous plugs have a history of bronchial asthma, bronchial hyperreactivity or previous cardiac surgery (often a Fontan procedure). A foreign body may itself be radiopaque. Associated findings, such as an interrupted bronchus (Fig. 5), pneumomediastinum (Fig. 6) or subcutaneous emphysema, can also be observed in children with an Fig. 2 Chest radiograph shows a large amount of right pleural fluid with contralateral mediastinal shift. Pleural tap yielded a large amount of chyle endobronchial foreign body or tumour, and with bronchial obstruction secondary to mucous plugging. Patients with clinically suspected bronchial aspiration require immediate bronchoscopy. Further diagnostic imaging is usually contraindicated. By contrast, CT and/or MRI are the diagnostic techniques of choice when dealing with unexplained unilateral atelectasis or when extrinsic bronchial compression by tumour, enlarged lymph nodes or abnormal vascular structures is suspected. With contralateral mediastinal displacement In this group, the differential diagnosis includes isolated pleural effusion, congenital malformations (particularly when secondarily infected), pneumonia with pleural effusion, tumour, and some vascular lesions [7 9]. Chest US is mandatory in the work-up of these patients [5, 10 12] since it can identify and characterize pleural effusions (Fig. 7). It can also evaluate the degree of vascularisation in pulmonary infectious consolidations and provides the same prognostic information as contrast-enhanced CT [13]. Further, it can distinguish pulmonary consolidation from tumour. Sonographic air bronchograms (Fig. 8) and pulmonary vessels within a lesion are characteristic sonographic features of lung consolidation and are never seen in isolated pleural effusion or in tumour. Differentiation between air bronchograms and pulmonary vessels can be made by colour Doppler sonography. Pulsed Doppler permits differentiation of pulmonary and systemic arteries. While the (pulmonary circulation) arteries within a consolidation show a characteristic polyphasic (mainly quadriphasic) pattern (Fig. 8), those within a pulmonary sequestration or an extrapulmonary intrathoracic tumour will show a systemic (biphasic) pattern (Figs. 3, 9). This emphasizes the value of pulsed Doppler in the assessment of pulmonary masses. In our practice, chest US has replaced contrast-enhanced chest CT in the assessment of children with pneumonia. However, CT or MRI is required whenever US reveals

3 Fig. 3 A newborn with respiratory distress. a Chest radiograph shows a white left hemithorax with contralateral mediastinal displacement. b, c Chest ultrasound demonstrates a left pleural effusion and a large echogenic supradiaphragmatic mass that, on colour Doppler, appears to be supplied by a large vessel with a systemic wave pattern. d Coronal image of chest CT confirms the presence of the pleural effusion, the supradiaphragmatic mass and its aortic supply. An extralobar sequestration was found at surgery (courtesy of C. Martin, UDIAT, Spain) Fig. 4 A 10-month-old girl with a few episodes of bronchitis. Chest radiograph shows a white right hemithorax with ipsilateral mediastinal shift. Final diagnosis: right pulmonary agenesis Fig. 5 A 10-year-old boy with severe cough and a history of choking whilst eating peanuts. The left lung is decreased in size and the mediastinum is shifted to the left. The air-filled left main bronchus is interrupted abruptly (arrow). The right lung is over-aerated and is herniated to the left. At bronchoscopy, a peanut was removed from the left main bronchus

4 Fig. 6 A 3-year-old boy with severe cough of sudden onset. Chest radiograph shows an opaque left lung with interrupted main bronchus and associated left pneumomediastinum (arrows). The latter two findings are characteristic of bronchial obstruction. At bronchoscopy, a sunflower seed was removed from the left main bronchus Fig. 8 Pulmonary consolidation in a 6-year-old boy with pneumonia. a Typical appearance of sonographic air bronchograms seen as echogenic branching lines (arrow). A pulmonary vessel is also seen (arrowhead). b Pulsed Doppler shows the typical quadriphasic pattern of a pulmonary artery. Taken from Lucaya and Strife (2008) Pediatric chest imaging, 2nd edn, p 10, Chest US, Figs and 1.14, with kind permission of Springer Science & Business Media Fig. 7 A 2-year-old girl with streptococcal pneumonia. a Chest radiograph shows a white left hemithorax with contralateral mediastinal displacement. b Chest US reveals a large pleural effusion with a honeycomb pattern surrounding an area of collapsed lung (L) features suggestive of tumour, malformation or vascular disorder (Fig. 10). Lymphomas and teratomas are the most common anterior mediastinal tumours. These may present with a large opaque hemithorax (Figs. 11, 12). Lymphoma is the most common cause of neoplastic pleural fluid in children. Identification of a large mediastinal mass is the key to a correct diagnosis. Pleural effusions are seen in approximately 10% of patients with mediastinal lymphoma and may be due to lymphatic compression or pleural metastasis. Large pleural effusions due to pleural metastasis may also occur in neuroblastoma (Fig. 13), Wilms tumour,

5 Fig. 9 A 7-year-old girl with cough, fever and mild tachypnoea. a Chest radiograph demonstrates a white right hemithorax and left-sided mediastinal displacement. A right paratracheal air collection is also seen, which might correspond to air from a previous tap. b Doppler US shows a characteristic systemic wave pattern (biphasic), a finding that rules out pneumonia and establishes the need for further imaging. c Chest CT confirms the presence of a solid mass, some costal erosion (arrow) and a small pleural effusion. The final diagnosis was a Ewing family tumour Fig. 10 A 5-year-old boy with fever of 3 months duration. a Chest radiograph shows an enlarged white left hemithorax and a curvilinear interface crossing the low dorsal spine (arrows). b Chest US and Doppler shows a small pleural effusion and a vascular lesion. c MRI confirms the presence of a large aortic aneurysm and a small pleural effusion. The final diagnosis was Takayasu arteritis

6 Fig. 11 A 11-year-old boy with progressive dyspnoea over several months. a Chest radiograph depicts a white left hemithorax with some calcifications. b Contrast-enhanced CT shows a large heterogeneous mass with cystic spaces, fat and calcifications. c Coronal reformats show pleural effusion and a huge mass displacing the mediastinal structures. A mediastinal mature teratoma was confirmed at surgery. Courtesy of L. Cadavid, Pontificia Universidad Católica de Chile Fig. 12 A 3-year-old boy with a history of treated T-cell lymphoma that had responded to chemotherapy, presented with a week-long fever and respiratory distress. Decreased breath sounds were noted on physical examination. a Chest radiograph demonstrates a white left hemithorax with contralateral mediastinal shift. b Pleural fluid and multiple pleurally based echogenic masses are seen at chest US. c CT confirms the presence of a large left-sided anterior mediastinal mass with lung collapse, large pleural effusion and pleural nodules. Final diagnosis was relapsed T-cell lymphoblastic lymphoma. Taken from Lucaya and Strife (2008) Pediatric chest imaging, 2nd edn, p 19, Chest US, Fig. 1.30a, with kind permission of Springer Science & Business Media

7 Fig. 13 A 2-year-old boy with respiratory distress and fever. a Chest radiograph shows a large, homogeneously white left hemithorax. b, c CT reveals a huge pleural effusion and a solid, multi-lobulated, partially calcified left chest mass invading the extradural space (arrow). Final diagnosis was neuroblastoma rhabdomyosarcoma or other malignancies. Huge pleural effusions are also seen in lymphangiomas with rib osteolysis (Gorham disease, Fig. 14). Primary pulmonary tumours are rare in children. Pleuropulmonary blastoma is the most common (Fig. 15) and may present with or without associated pleural fluid; however, chest wall lesions are usually absent [14]. By contrast, rib involvement is extremely common in the Ewing family of tumours [15] (Fig. 9). Therefore, when assessing a large opaque hemithorax, the radiologist should carefully assess the chest wall for osseous lesions. These may be difficult to identify on plain films (Fig. 9), but are easily recognizable at CT (Fig. 9). Soft tissue tumours, such as rhabdoid tumour, and lung metastases (with or without associated pleural effusion), may also present with a large opaque hemithorax [16] (Figs. 16, 17). Fig. 14 A 16-month-old girl with mild respiratory distress. a Chest radiograph shows a large, homogeneously white right hemithorax. The right clavicle has a permeative pattern of abnormality (arrow). b Repeated chest radiograph after a pleural tap of 300 ml chylous fluid better demonstrates the abnormality of the right clavicle (arrow) and significant thinning of the second right rib (arrowhead). Final diagnosis was Gorham disease

8 Fig. 15 A 20-month-old boy presented with dyspnoea. a Chest radiograph shows an enlarged, homogeneously white left hemithorax. b Significant pleural effusion, a multilobulated paravertebral soft tissue mass and pleurally based soft tissue nodules are seen at CT. There is no evidence of bone lesions. The diagnosis was pleuropulmonary blastoma. Courtesy of M. Pons, Valencia, Spain Fig. 16 A 5-year-old boy with fever and cough. Physical examination revealed decreased breath sounds on the right. a Chest radiograph demonstrates an enlarged white right hemithorax. b CT confirms the presence of a huge right-sided chest mass displacing the mediastinal structures. Several areas within the mass did not enhance following the administration of intravenous contrast material. The final diagnosis was thoracic rhabdoid tumour originating from the soft tissues of the inner aspect of the posterior chest wall Fig. 17 A 17-year-old boy with known osteosarcoma of the left femur developed respiratory distress. a Chest radiograph shows a large white left hemithorax. b Nonenhanced CT demonstrates large, partially ossified metastases in the left lung, and one in the right lung. Taken from Lucaya and Strife (2008) Pediatric chest imaging, 2nd edn, p 15, Chest US, Fig. 1 with kind permission of Springer Science & Business Media

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