Case report: Primary pleural giant extraskeletal Ewing sarcoma in a child

Abstract

Primary extraskeletal Ewing sarcoma (EES) is a rare small round cell malignancy that accounts for less than 1% of all sarcomas. It is found most commonly in the trunk and lower limbs and very rarely in the pleura and can be easily misdiagnosed in clinical practice. This study presents the case of an 11-year-old boy who presented to our hospital with no apparent cause of left shoulder pain for 6 months. On physical examination, tenderness was noted in the left chest wall and shoulder joint, which had a limited range of motion. Computed tomography (CT) and magnetic resonance imaging (MRI) of the chest revealed an irregular soft tissue mass in the upper left thorax, with a wide base attached to the adjacent pleura and bone destruction of the adjacent left first rib. The patient's bone scan showed a dense focus of increased radiotracer accumulation in the left first rib. A subsequent CT-guided aspiration biopsy of the left pleural mass with histomorphology and immunohistochemical phenotyping led to a diagnosis of extraskeletal Ewing sarcoma. To inhibit tumor growth, alternating systemic chemotherapy cycles of vincristine, doxorubicin, and cyclophosphamide (VDC) and isocyclophosphamide and etoposide (IE) were administered at 3-week intervals. After completing three VDC and two IE cycles, the child's condition was well and the pain in the left shoulder joint was relieved. However, a repeat MRI of the chest showed that the mass did not shrink.

Keywords: case report; computed tomography; extraskeletal Ewing sarcoma; intrathoracic tumor; malignancy.

Figure 1

Chest computed tomography (CT) images (A–F). (A) Irregular soft tissue density mass in the upper left thorax. (B) The mediastinal window shows a lamellar hypodense shadow within the mass (arrow). (C) The bone window shows bone destruction of the left first rib and visible periosteal new bone formation (arrow). (D) Mild to moderate heterogeneous enhancement of the lesion with non-enhancing hypodense areas within it (arrow). (E) Persistent enhancement of the lesion in the venous phase. (F) The sagittal section shows bone destruction of the left first rib (yellow arrow) and lamellar hypodense areas within the mass (red arrow).

Figure 2

Magnetic resonance imaging (MRI) of the thorax (A–G). (A, B) An irregular soft tissue mass is seen in the upper part of the left thorax, showing a mixed signal dominated by iso-T1 and iso-T2 signals. (C) T2WI lipid suppression shows a heterogeneous slightly high signal; few long T2 signals are seen within the mass (arrow). (D) The solid part of the mass shows a distinct high signal on DWI. (E) This corresponds to a low signal on the ADC map. (F) The solid part of the lesion is heterogeneously enhanced; no enhancement is seen in the internal liquefied necrotic area (arrow). (G) The enhanced sagittal view reveals a bony destruction of the left first rib (blue arrow) and a lamellar area of non-enhancement within the mass (white arrow).

Figure 3

Immunohistochemistry. (A) Hematoxylin and eosin (HE) staining (×200); (B) HE staining (×400); (C) CD99 (++++) (×200); (D) CD99 (++++) (×400); (E) NKX2.2 (++++) (×200); (F) NKX2.2 (++++) (×400).

Figure 4

Timeline.