Contribution of magnetic resonance imaging in the diagnosis of talus skip metastases of Ewing's sarcoma of the calcaneus in a child: a case report

Abstract

Introduction: Ewing's sarcoma of the calcaneus is rare. About thirty cases with calcaneus involvement have been reported in the literature. Talus skip metastases have rarely been described in the available literature

Case presentation: We report a case of a 14-year-old Moroccan boy, who presented with Ewing's sarcoma of his right calcaneus, diagnosed by swelling of the calcaneus evolving over a year. Radiography, computed tomography and magnetic resonance imaging showed an important tumoral process of the calcaneus and talus skip metastases. The diagnosis was confirmed with histology after a biopsy. In spite of amputation and postoperative chemotherapy, our patient died six months later due to secondary respiratory distress after lung metastasis.

Conclusion: Imaging, especially magnetic resonance, is important in the diagnosis of Ewing sarcoma and skeletal skip metastases. Treatment of Ewing's sarcoma consists of chemotherapy, radiation therapy and surgical resection depending on the stage and extent of the disease. With the exception of lesions in the calcaneus, the prognosis for disease-free survival of Ewing's sarcoma of the foot is excellent.

Figure 1

Anteroposterior radiographs of patient's foot show a lesion in the calcaneus condensed with aggressive periosteal reaction and soft-tissue swelling.

Figure 2

Lateral radiographs of the patient's foot show a condensed lesion in the calcaneus with aggressive periosteal reaction and soft-tissue swelling.

Figure 3

CT image of the patient's foot, revealing a soft-tissue mass originating from the calcaneus, permeative destruction of the entire bone with aggressive spiculated periosteal reaction and cortical destruction.

Figure 4

MRI of the patient's foot shows a hypointense tumor mass on T1-weighted spin-echo sequences compared to surrounding musculature. The skip lesion of the talus displays a hyposignal on T1-weighted sequences.

Figure 5

MRI of the patient's foot shows a hyperintense tumor mass on T2-weighted spin-echo sequence images compared to surrounding musculature. The skip lesion of the talus displays a hyposignal on T2-weighted sequences.

Figure 6

T1-weighted fat saturation sequence after intravenous gadolinium chelate administration reveals strong contrast enhancement of the tumor. We note the skip lesion in the talus as a low signal mass with peripheral enhancement.