Teaching Case

A thirteen-year-old boy presented with progressive painful swelling over the centre of the chest for 3 months. His vitals were stable on presentation at the hospital. Examination confirmed a firm tender swelling over anterior chest covering the sternum. A chest radiograph followed by a contrast-enhanced CT of the chest and upper abdomen was done.

The Chest radiograph (PA view) demonstrated an ill-defined central mass occupying the mediastinum with poorly maintained margins with the mediastinal vascular structures and cardiac silhouette. Multiple well-defined rounded opacities were noted in bilateral lung fields. Right-sided pleural effusion was also present (Figure 1).

Imaging by CECT revealed a large ill-defined heterogeneously enhancing soft tissue lesion which demonstrated permeative destructive pattern within the manubrium and upper half of the sternum, extending into the anterior mediastinum and loss of fat plane with adjacent chest wall muscles (Figure 2). Multiple widespread lung nodules and right-sided pleural effusion were noted (Figure 3).

A large ill-defined heterogeneously enhancing right adrenal mass was detected (Figure 4).

Based on the imaging findings, a provisional diagnosis of Ewing’s sarcoma with lung and adrenal metastasis was made.

Background

10-15% of all primary bone tumours are Ewing's sarcomas, the second most frequent malignant bone tumour in adolescents and young adults. Although Ewing's sarcoma can affect any bone, the lower extremity (45%), pelvis (20%), upper extremity (13%), axial skeleton and ribs (13%), and face (2%) are the most prevalent places. The femur is the most frequently affected bone, with the tumour usually arising in the midshaft [4]. 10-15% of all primary chest wall tumours are Ewing sarcomas [5].

Imaging Perspective

When Ewing's sarcoma is detected on a CT scan, the mass is often big, poorly defined, and appears inhomogeneous due to widespread cystic degeneration. Calcification may or may not be present. Smaller tumours tend to be more homogeneous, but larger tumours manifest as heterogeneous masses that commonly show signs of haemorrhage or necrosis [6]. Despite being aggressive, these tumours frequently displace nearby structures at first. However, direct infiltration can destroy ribs and is more common in bigger tumours [5]. Primary adrenal cancer is less common than adrenal metastases. Sarcoma-related metastases to the adrenal glands are uncommon and typically accompany large metastases that affect numerous organs at once [7].

Rhabdomyosarcoma are the most common soft tissue tumour in children. They are usually located in the orbits, but approximately 7% are found in the trunk and thorax. The appearance of the mass is non-specific and indistinguishable from other sarcomas; however, adjacent bone destruction is seen in over 20% of cases [5].

Outcome

One of the most potent indicators of a poor prognosis is the presence of disseminated illness, which can be identified through imaging, cytological testing, and histological analysis of the bone marrow at the time of diagnosis in ESFT [3]. A surgical resection and neoadjuvant chemotherapy and radiotherapy are used as treatments. Long-term survival is possible for people whose tumour is contained to the chest. Overall 5-year survival is between 15-48% [8].

The patient then underwent ultrasound-guided biopsy of the mass. Light microscopy showed multiple small round blue cells with a high nucleo:cytoplasmic ratio arranged in sheets and clusters (Figure 5). On Immunohistochemistry (IHC), the tumour cells were positive for CD99 and negative for K, LCA, Synaptophysin, Desmin and Myogenin. The pathology report favoured Ewing's sarcoma.

Being metastatic on presentation, the patient was started on combination chemotherapy.

Written informed patient and parents’ consent for publication has been obtained.