PRIMARY METASTATIC PLEURAL EWING SARCOMA IN A YOUNG ADULT: A CASE REPORT AND LITERATURE REVIEW

Background:Ewing sarcoma (EWS) is a highly aggressive small round cell tumor that typically arises in bone or soft tissue. Primary pleural involvement is exceedingly rare, particularly in young adults, and its management remains challenging due to its non-specific presentation and rapid progression. Case Presentation:We report the case of a 20-year-old male presenting with a six-month history of progressive left laterothoracic swelling, intermittent pleuritic pain, dyspnea, and a 10 kg weight loss. Chest CT revealed a large pleural-based mass measuring 144 × 110 × 147 mm, with local chest wall invasion and multiple osteolytic metastases (ribs, D6, D8, D12, L3, sacrum, and ilium). A CT-guided biopsy showed a small round cell tumor with diffuse CD99 expression, negative lymphoid markers, and a Ki-67 proliferation index of 60%, consistent with Ewing sarcoma. The patient received three cycles of dose-dense VDC/IE chemotherapy with G-CSF support. Imaging showed a marked reduction in the primary pleural mass but progression of bone metastases.Despite this mixed response, treatment was continued. During the fifth cycle, the patient developed clinical deterioration with desaturation, tachypnea, and massive pleural effusion. Ultrasound guided thoracentesis yielded milky fluid. The patient was subsequently lost to follow-up and later died before a scheduled CT scan.