Rare presentation of Ewing's sarcoma underscores the diagnostic challenges in atypical cases

A female patient in her late teens presented with an initially episodic right-sided chest pain that gradually became persistent and associated with a high-grade fever, starting 15 days earlier but worsening over a week. Physical examination revealed tenderness on the right side of the chest and reduced air entry in the right middle and lower lung fields. Initial imaging demonstrated a right-sided pleural effusion with a chest wall mass lesion. A chronic infection like tuberculosis (TB) was suspected. However, an ultrasound-guided thoracentesis confirmed an exudative pleural effusion with low adenosine deaminase. Further, fine needle aspiration cytology of the mass revealed atypical small round cells with scanty cytoplasm and an immunohistochemistry profile consistent with Ewing's sarcoma. This case highlights the diagnostic challenges accompanying an unusual presentation of Ewing's sarcoma in the TB endemic region, which typically affects long bones but, in this instance, is manifested with pleural involvement and symptoms.