Abstract:

Background and Purpose: Primary Ewing sarcoma of the thoracic wall (PEST) is a rare extraosseous Ewing sarcoma that occurs in the chest wall or thoracic cavity with a short survival, poor prognosis and a high rate of recurrence. Early diagnosis and treatment are the best way to prolong survival time since the cause of PEST is not clear. This study aimed to explore the clinicopathologic characteristics, diagnosis and treatment of PEST to improve clinical understanding of this disease. Methods: A total of 21 cases with PEST were treated at The First Affiliated Hospital of Soochow University, and reviews were published from 2018 to 2023. Clinical data, pathological features, treatment and follow-up of the patients were analyzed respectively. The survival was from the start of treatment to the death of the patient or the end of the follow-up. Cumulative survival was estimated by Kaplan-Meier method. Results: A total of 21 cases with PEST (male/female ratio, 13:8; sites of left/right chest ratio, 6:15; median age, 20 years; mean age, 28 years; median diameter of the tumor, 8.0 cm; mean diameter of the tumor, 18.1 cm) met the inclusion criteria. 65.2% of the patients presented with the pain in the ipsilateral thoracic and abdominal area. In 47.1% of cases, the ipsilateral ribs were invaded with pleural effusion. Pathological morphology microscopy showed most tumor cells were tightly packed or lobular distribution of small blue round cells. In immunohistochemistry, CD99 and vimentin were positive in 100% and 80% cases respectively while neurogenic markers were expressed to varying degrees. EWSR1 separated signal was found by fluorescence in situ hybridization (FISH), and the EWSR1-FLI1 fusion was detected by next-generation sequencing (NGS) in two cases at our hospital. Two cases received neoadjuvant chemotherapy, 10 patients received chemotherapy and radiotherapy after operation, 5 cases were treated with radiotherapy only, 1 case received surgery only, and 3 cases had no surgical data. A total of 14 cases were followed up for 3-38 month while 7 cases were lost to visit. Cumulative survival correlates with age at disease. The mean survival time was 19.98 months, and the median survival time was 13.00 months. Conclusion: Young males, right chest and the mass larger than 8 cm are more often found. Most cases can be initially diagnosed using histopathology and immunohistochemical markers. FISH or NGS of the EWSR1 gene test are a highly accurate method for diagnosis. The prognosis of PEST is extremely poor, and the cumulative survival rate is negatively correlated with the age of onset. Surgery, radiotherapy and chemotherapy are the main treatments for this disease.

Key words: Primary Ewing sarcoma of the thoracic wall, Clinicopathological features, Treatment, EWSR1-FLI1