CASE 8555 Published on 01.08.2010

Ewing\'s sarcoma presenting as a posterior mediastinal mass

Section

Chest imaging

Case Type

Clinical Cases

Authors

Duarte R1, Miranda D2, Mato H3, Sanches C3, Noruegas MJ3, Coelho P3

1Centro Hospitalar de Gaia/ Espinho
2Unidade Local Saúde Matosinhos - Hospital Pedro Hispano
3Centro Hospitalar de Coimbra

Patient

10 years, female

Clinical History
A 10-year-old girl with no significant past medical history referred to our institution with a two-month history of posterior thoracic chest pain, which was aggravated by coughing and accompanied by anorexia, weight loss and cachexia.
Imaging Findings
A 10-year-old girl with no significant past medical history was referred to our institution with a two-month history of posterior thoracic pain, which was aggravated by coughing and accompanied by anorexia, weight loss and cachexia. Physical examination and laboratory tests were unremarkable. Upright posteroanterior and lateral chest radiographs showed a large well-marginated rounded mass in the posterior mediastinum (Fig. 1).
Chest CT revealed a midline well-defined soft-tissue mass with a diameter of 12 cm, located in the posterior mediastinum, adjacent to the vertebral bodies from T3 to T8, encasing the descending aorta (Fig. 2). The mass was associated with permeative destruction and osteosclerosis of the 6th thoracic vertebral body (Fig. 2 d-e). There was also extension to the spinal canal through the neural foramina at the 6th to 7th thoracic vertebrae (Fig. 2).
Axial T1-weighted, T2-weighted and contrast-enhanced T1-weighted MR images confirmed extension to the spinal canal with involvement of epidural space, displacing the spinal cord posteriorly (Fig. 3 a-c). Coronal and sagital T2-weighted MR images depicted cranial and caudal extent of the tumour (Fig. 3 d-e), as well as the extension to the spinal canal though the neural foramina at the 6th to 7th thoracic vertebrae (Fig. 3 e).
Cross-sectional imaging investigation for staging was negative for metastatic involvement.
The patient underwent biopsy under thoracoscopy and the tumour was diagnosed as a Ewing's sarcoma. The tumour was considered unresectable at initial presentation and chemotherapy was initiated in order to reduce its size and allow potential future complete tumour resection.
Discussion
In childhood most of posterior mediastinal masses are of neurogenic origin [1]. Ewing’s sarcoma family of tumours, which includes Ewing’s sarcoma, primitive neuroectodermal tumour, neuroepithelioma, and Askin tumour are a rare cause of posterior mediastinal mass and may present with intraspinal extension [2, 3, 4]. These tumours are thought to derive from neural crest cells and genetic analysis revealed that they are associated with a balanced reciprocal translocation between chromosomes 11 and 22, that is t (11; 22) (q24, q12) [5, 6]. Ewing’s sarcoma is composed of small round cells typically with cytoplasmic glycogen, a feature used to differentiate it from primitive neuroectodermal tumours [5, 6]. These tumours are the most common primary spine non-lymphoproliferative tumours in children, which account for 3% to 10% of all primary sites [3]. The tumours are usually centred in the vertebral body, although the extent to posterior elements is not uncommon [3].
The clinical presentation of these tumours includes fever, malaise, cough, dyspnoea and painful, palpable mass [1, 6].
Ewing’s sarcomas have a male predominance of 1.6:1, and usually occur in patients between 3 and 25 years of age (mean, 13 years) [6]. They typically arise from the bony skeleton with the characteristic radiologic manifestation of a mass associated with bone destruction [6]. Rarely, they can manifest as a large mass with only a small component of bone involvement [6]. Occasionally it may have an extraskeletal origin, usually in the paravertebral region and extend through the neural foramina, and bone involvement is typically absent [5].
These tumours usually tend to displace adjacent structures by mass effect than invade them, although large tumours may directly infiltrate the surrounding structures [5].
At CT and MR, small lesions are usually homogeneous, whereas large lesions tend to be more heterogeneous, due to haemorrhage or necrosis [5]. On MRI T1-weighted images, these tumours generally show iso or hyperintensity compared with the muscle, as well as heterogeneous hyperintensity on T2-weighted images [5, 7]. After intravenous administration of contrast media, these lesions usually show marked heterogeneous enhancement [5, 7]. Imaging findings of Ewing’s sarcoma are nonspecific [7]. Nevertheless, the imaging modalities are essential in the assessment of the tumour extension and proper treatment planning [7].
Complete tumour resection is the best change of cure and large lesions may require pre-operative chemotherapy and radiation therapy to reduce the tumour and allow curative resection [3, 7]. The prognosis depends essentially on the presence of metastases, which occurs in about 75% of patients, with a 5-year survival rate less than 30% in the presence of metastases versus a 5-year survival near 100% in the absence of metastases [6].
Differential Diagnosis List
Ewing's sarcoma.
Final Diagnosis
Ewing's sarcoma.
Case information
URL: https://www.eurorad.org/case/8555
DOI: 10.1594/EURORAD/CASE.8555
ISSN: 1563-4086