Primary Ewing’s Sarcoma of the Sternum in an Adult Male: A Rare Case Report

Abstract

Ewing’s sarcoma, a rare primary bone malignancy primarily affecting adolescents and young adults, typically manifests in the pelvic bones and femur. Primary Ewing’s sarcoma of the sternum is exceptionally rare, constituting less than 1% of cases. We present a case of a 34-year-old man with a 2-month history of anterior chest wall pain initially attributed to muscular spasm. Subsequently, the patient developed a palpable mass and imaging demonstrated a mid-lower sternal lesion with cortical destruction and soft tissue involvement, confirmed as Ewing’s sarcoma on biopsy. In addition, a suspicious lesion was identified in the left distal tibia, which was histologically confirmed as a metastasis from the primary sternal sarcoma. Neoadjuvant chemotherapy preceded partial sternotomy with rib resection and reconstruction, achieving clear surgical margins. Postoperative evaluation showed shrinkage in the sternal lesion and near-resolution of the tibial metastasis. Subsequent chemotherapy cycles resulted in no evidence of the disease on the follow-up positron emission tomography scan. This case underscores the diagnostic challenges of primary sternal Ewing’s sarcoma and emphasizes the importance of early recognition and comprehensive evaluation in managing such rare presentations.

Background

Ewing’s sarcoma, a malignant neoplasm originating from bone or soft tissue, represents the second most common primary bone malignancy in adolescents and young adults.^1,2 It predominantly arises in the pelvic bones and femur, followed by the chest wall and lower leg. Notably, primary Ewing’s sarcoma of the sternum is exceedingly rare, comprising less than 1% of all cases. ³

The clinical presentation of sternal Ewing’s sarcoma typically involves insidious onset of localized pain or swelling, which can be easily mistaken for conditions such as costochondritis or musculoskeletal chest pain. This nonspecific symptomatology complicates the diagnostic process, requiring a high degree of clinical suspicion for accurate identification.^4,5

In this report, we present an exceptional case of primary sternal Ewing’s sarcoma, highlighting its rarity and underscoring the critical need to consider this diagnosis in evaluating sternal masses.

Case Presentation

A 34-year-old man, with no significant medical history except for an appendectomy, presented with a 2-month history of anterior chest wall pain. This pain, initially treated as muscle spasm, did not improve and later was accompanied by a noticeable bulge on his chest.

Seeking further evaluation, the patient underwent a computed tomography (CT) scan, which revealed a bony lesion in the mid-lower sternum, showing signs of cortical destruction and a soft tissue component, suggesting a malignant process as shown in Figure 1. To further investigate, a positron emission tomography (PET) scan was performed and showed an intensely hypermetabolic lesion in the sternum, indicating high metabolic activity typical of neoplastic tissue. In addition, there was a suspicious lesion in the left distal tibia as the PET scan showed a moderately hypermetabolic lesion suggestive of metastasis (Figure 1).

Figure 1.

Sagittal CT image at the time of diagnosis shows an abnormal density in the sternum with a large soft tissue component.

A biopsy of the sternal lesion was conducted, revealing neoplastic cells consistent with Ewing’s sarcoma. The cells tested positive for Vimentin, CD99, and Flit, confirming the diagnosis.

The patient underwent 4 cycles of neoadjuvant chemotherapy (Vincristine, Ifosfamide, and Doxorubicin) to shrink the tumors before surgery. After chemotherapy, a follow-up PET scan showed significant regression of the sternal lesion and near-resolution of the tibial lesion, indicating a good response to the treatment.

The patient then had a partial sternotomy with reconstruction. This procedure involved a 10-cm incision with the resection of the sternum and ribs 3 to 7. Reconstruction involved the use of a metallic plate for the third rib and bone cement bars for the remaining ribs, with 1 bar placed vertically. All were fixed using sternal wires. Two biopsy specimens were obtained, one from the sternal tissue and one from the tibia. Each specimen was carefully collected and sent for pathological examination.

Postoperative recovery was uneventful, and histopathological examination of the resected sternal tissue showed no residual tumor, with the tibial sample showing unremarkable bone marrow elements. This indicated the absence of active malignancy in the tibia. This finding supported the conclusion that the focal increased Fluorodeoxyglucose uptake observed in the initial PET scan, suggestive of secondary metastasis from the primary sternal Ewing’s sarcoma, had markedly regressed following neoadjuvant chemotherapy.

The patient completed a total of 11 cycles of chemotherapy. A comprehensive PET scan after the final chemotherapy cycle indicated no active neoplastic lesions and showed typical postoperative changes with no new concerning areas of high metabolic activity. The patient exhibited an excellent response to the treatment. One-year follow-up showed no recurrence of the neoplasm.

Discussion

Ewing’s sarcoma can arise in any bone, with the lower extremity being the most common site (45%), followed by the pelvis (20%), upper extremity (13%), axial skeleton and ribs (13%), and face (2%). The femur is frequently affected, often originating in the midshaft. Histologically, the tumor typically comprises small round cells with regular nuclei containing finely dispersed chromatin and inconspicuous nucleoli, along with a narrow rim of clear or pale cytoplasm. ⁶

Primary Ewing’s sarcoma originating from the sternum is exceptionally uncommon; less than 1% of primary cases of Ewing’s sarcoma occur in the sternum, with limited documentation available in the literature. ³ A thorough literature review uncovered approximately 7 cases of primary Ewing’s sarcoma arising from the sternum with the first one being reported in 1957.^{4,5,7 -10}

Most cases were identified among cohorts of patients with no available clinical data. One study identified a case within a series of 107 cases at Tara Memorial Hospital in Bombay, India. ⁸ Another study of bone tumors at the Mayo Clinic revealed that primary malignant sternum tumors constituted only 0.6% of cases, with one case of Ewing’s sarcoma representing only 1.5% of these. ⁹ Similarly, a long-term analysis at Memorial Sloan Kettering Cancer Center spanning nearly 7 decades identified Ewing’s sarcoma as a rare occurrence among primary sternal malignancies, accounting for only 1.7% of cases. ¹⁰

Patients typically present with localized pain or swelling, evolving over weeks to months. Metastases are often subclinically present at diagnosis. Diagnostic modalities such as chest CT scans and bone scintigraphy are essential for detecting metastatic disease, with biopsy serving as the definitive diagnostic tool. ¹¹

Multimodal therapy, including neoadjuvant chemotherapy followed by surgical intervention and/or radiotherapy, has substantially improved the 5-year survival rate to 60% to 70%. Radical surgical resection is preferred, although sternum and anterior chest wall resections pose challenges necessitating meticulous planning for functional preservation. ¹¹ Achieving wide resection margins, as per the Enneking classification, involves ensuring at least 2 cm of tumor-free tissue bilaterally. ¹² However, many institutions opt for wider margins (3-5 cm) to minimize local recurrence risks. This often entails resection of adjacent ribs above and below the affected area. Deeper dissection is crucial to evaluate potential invasion into surrounding structures such as the pleura, thymus, and lungs, with necessary resection if indicated. Total sternotomy is not always necessary; subtotal or partial sternotomy may suffice to achieve adequate margins. ⁴

Only 3 distinct cases illustrate varied presentations and treatment strategies.

The first case involved a 30-year-old man with worsening chest pain and a fixed parasternal swelling. Imaging revealed a mass with intraosseous and soft tissue components. Following 3 cycles of neoadjuvant chemotherapy, he underwent sternal resection and reconstruction using a polypropylene-methyl methacrylate graft and a pedicled latissimus dorsi flap. Postoperative complications included a pneumothorax, which was managed successfully, and the patient was discharged in good condition. ⁴

The second case involved a 16-year-old boy who presented with an enlarging chest wall mass, tenderness, and a 30 lb weight loss, but no chest pain or shortness of breath. A CT scan revealed a calcified mass in the anterior sternum extending into the anterior mediastinum. Biopsy confirmed Ewing’s sarcoma, and the patient was treated with 12 cycles of chemotherapy. The tumor size decreased by two-thirds. Five months later, the tumor was excised with 1.5 cm negative margins, and one-third of the sternum along with adjacent intercostal muscles and rib ends were removed. The plastic surgery team reconstructed the defect using AlloDerm over the heart, polypropylene mesh, and a tunneled latissimus dorsi muscle flap. The patient recovered well postoperatively and was discharged on postoperative day 10. He remains in good health 1 year after diagnosis, with no evidence of recurrent tumor. ⁷

The third case featured a 12.5-year-old girl who first experienced chest pain in May 1976. Initial chest x-rays were normal, but by May 1977, worsening pain and fever led to the discovery of a large mass behind and slightly below the manubrium on x-ray and CT scan. An open biopsy confirmed Ewing’s sarcoma. She received radiation therapy (5000 rads) and chemotherapy, which led to partial tumor necrosis. In August 1977, she underwent resection of the manubrium and mediastinal mass, with histology showing no viable tumor cells. The defect created by the resection was repaired using Marlex mesh. Postoperative complications included bilateral pneumonia and a right pleural effusion, which were managed successfully. Two years post-diagnosis, she remained free of disease. ⁵

In our case, the patient underwent 4 cycles of chemotherapy before partial sternotomy was performed with resection of adjacent ribs which then was followed by 7 cycles of chemotherapy.

Conclusions

In conclusion, primary Ewing’s sarcoma of the sternum is a rare condition that often presents initially with nonspecific symptoms, which can mimic musculoskeletal disorders. This case emphasizes the critical importance of considering Ewing’s sarcoma as a differential diagnosis when evaluating sternal masses, especially in the presence of ambiguous clinical signs.

Multimodal therapy, combining chemotherapy and precise surgical intervention with thorough margin control, plays a pivotal role in achieving favorable treatment outcomes. The successful management of this case highlights the effectiveness of current therapeutic strategies. This approach ensures comprehensive patient care and optimal management of rare presentations of Ewing’s sarcoma, emphasizing the importance of investigating for metastatic spread during clinical evaluation and follow-up.