Chest wall or pleural-based tumours represent a heterogeneous group of lesions that are infrequent in children and infants; however, a large proportion of these lesions are malignant in nature. Categorising them on the basis of primary versus secondary, site of origin (osseous and cartilage, or soft tissue) and tissue composition may assist in narrowing the differential diagnosis. We present a case of a 7-year-old boy with a progressive history of dyspnoea. The initial chest radiograph (CXR) demonstrated complete opacification of the left hemithorax with no air bronchograms. This was associated with the cut-off of the left main bronchus and mediastinal shift to the right. The post-contrast computed tomography (CT) of the chest showed multiple left-sided enhancing pleural-based masses with collapse of the left lung. These lesions were locally invasive as demonstrated by the intra and extra-thoracic extension. There were no associated erosions of the adjacent ribs or intra-tumoural calcifications. Based on the imaging findings, the diagnosis of extra-skeletal Ewing sarcoma (ES-EWS) of the chest wall was made with a differential diagnosis of rhabdomyosarcoma. A core biopsy was performed of the pleural-based mass, and histology with immunohistochemistry confirmed the diagnosis of a malignant small round blue cell tumour; subtype Ewing sarcoma family tumour (ESFT). The child was subsequently commenced on chemotherapy. The diagnosis of ES-EWS should be considered when a child or adolescent presents with an ill-defined, eccentric, chest wall mass in the absence of a lesion with a primary osseous origin. Imaging plays a key role in tumour staging, therapeutic planning and follow-up of patients.
Ewing sarcoma family tumours (ESFT) are a group of malignant small round blue cell tumours with varying degrees of neuroectodermal differentiation.
A 7-year-old boy presented with a progressive history of dyspnoea. A chest radiograph (CXR) was performed which demonstrated complete opacification of the left hemithorax with no air bronchograms. This was associated with a cut-off of the left main bronchus and mediastinal shift to the right (
Frontal chest radiograph (CXR): (a) Initial CXR on presentation demonstrates complete opacification of the left hemithorax with resultant mediastinal shift to the right and cut-off of the left main bronchus (black arrow); (b) CXR post left chest wall/pleural biopsy. Left pneumothorax (white arrow) with the left intercostal drain in-situ (black arrow). Associated surgical emphysema of the left chest wall (white stars).
(a–c) Axial, sagittal and coronal contrast-enhanced computed tomography images demonstrate left pleural-based masses which enhance heterogeneously (solid black arrows) with patchy hypodense regions suggestive of necrosis. There is an associated large complex left pleural effusion (white star), atelectasis of the left lung and mediastinal shift to the right. There were no associated intra-tumoural calcifications. Figure 2A – Note the extra-thoracic extension of the mass anteriorly via the intercostal spaces (white arrow) and another pleural-based mass that is inseparable from the pleural pericardial reflection (broken black arrow).
Axial computed tomography image of the chest on bone window demonstrates the absence of associated bony erosions (white arrow).
Based on the imaging findings, the differential diagnosis was categorised into three main groups:
Malignant soft tissue tumour (rhabdomyosarcoma, malignant peripheral nerve sheath tumour [MPNST], type II/III pleuropulmonary blastoma)
ESFT
Metastases (rhabdomyosarcoma, neuroblastoma, lymphoma, leukaemia)
Another differential consideration includes inflammatory myofibroblastic tumour (IMT) of the lung or pleura.
Biopsy of the anterior pleural-based mass was performed for histopathological confirmation. On microscopy, the specimen was composed of a proliferation of small round blue cells arranged in solid sheets. The background stroma was myxoid to oedematous in areas. Large areas of haemorrhage were also noted. The individual neoplastic cells were intermediate in size. The cells demonstrated oval nuclei with irregular contours and finely dispersed chromatin. Pinpoint nuclei were also noted in other areas. The cells had moderate amounts of pale eosinophilic cytoplasm. Brisk mitotic activity was noted with atypical forms seen. No rosettes were identified and a fibrillary background was not identified. No rhabdoid cells were seen. Periodic Acid-Schiff (PAS) and Periodic Acid-Schiff with diastase (PAS-D) stains highlighted focal glycogen within the neoplastic cells. These features were consistent with a malignant small round blue cell tumour of the chest wall/pleural biopsy.
The immunohistochemistry of the biopsy specimens was then performed to further subtype this neoplasm, which were consistent with ESFT.
No patient identifiable information has been presented.
J. Ewing first described EWS in 1921, and it is now believed to be the second-most common malignant bone tumour in children and adolescents after osteosarcoma.
The most common sites of occurrence of ES-EWS are the paravertebral region, lower extremities, chest wall, retroperitoneum, pelvis and hip, upper extremities, and head and neck region.
Extra-skeletal Ewing sarcoma typically manifests in children and young adults, with 85% of the reported cases being between 20 months and 30 years of age.
Ultrasound (US) offers the advantages of absence of ionising radiation, easy accessibility and a dynamic study that can be performed at the patient’s bedside, which can also guide needle-biopsy for the histological diagnosis. The US shows that these chest wall masses are often hypoechoic but can have anechoic regions if they are necrotic or haemorrhagic.
The CT findings depict an ill-defined, large, unilateral, soft-tissue chest wall mass, with heterogeneous enhancement post contrast.
The magnetic resonance imaging (MRI) findings, although non-specific, offer the added advantage in better delineating the margins of the mass and assessing its relationship with the surrounding structures and tumour staging.
Fluorodeoxyglucose Positron Emission Tomography (FDG PET) demonstrates increased radionuclide uptake and may be used in the detection of the primary lesion, residual or recurrent tumour or metastatic lesions.
Histologically, ESFT are small round blue cell tumours – a malignant group of neoplasms with a wide range of differentials.
Malignant paediatric chest wall tumours represent a diverse group of lesions; however, categorising them on the basis of primary versus secondary, site of origin (osseous and cartilage, or soft tissue) and tissue composition may assist in formulating the differential diagnosis.
Inflammatory myofibroblastic tumour of the lung usually appears as a solitary, well-marginated, peripheral mass on CXR with heterogeneous enhancement on CT.
As with all oncology cases, the mainstay of treatment is multidisciplinary. Biopsy is necessary to confirm the diagnosis after which neoadjuvent chemotherapy is initially used with the aim of decreasing the size of the primary lesion and eliminating micrometastases.
The thoraco-pulmonary location of ES-EWS is associated with a poorer prognosis in comparison to ES-EWS at other sites with the 2- and 6-year survival rates reported as 38% and 6%.
Extra-skeletal Ewing sarcoma is regarded a rare entity that has not been commonly reported but is an important consideration, given the poor prognosis. This diagnosis should be considered when a child or adolescent presents with an ill-defined, eccentric, chest wall mass, in the absence of a lesion with a primary osseous origin. The differential diagnosis should also include rhabdomyosarcoma of the chest wall, as this cannot reliably be differentiated from ES-EWS on imaging. Imaging plays a key role in tumour staging, therapeutic planning and follow-up of these patients.
The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.
D.M. was responsible for the review of literature, preparation of the case report as per journal’s requirements and compiling of the images. D.N.P. compiled the clinical information, radiological images and histology results and also assisted with the literature review. N.M. was responsible for the diagnosis of the case, interpretation of the imaging studies and editing of the final article.
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Data sharing is not applicable to this article as no new data were created or analysed in this study.
The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of any affiliated agency of the authors.