A rare mediastinal tumour in a young male mimicking massive pleural effusion.

A 30-year-old male, carpenter by profession, presented with a history of dry cough and progressive shortness of breath for two months along with right-sided chest pain for one and a half months. The clinico-radiological picture was suggestive of right-sided massive pleural effusion. Computed tomography (CT) scan of the thorax showed a huge mediastinal mass occupying the entire right hemithorax with very small amount of pleural effusion. CT-guided fine needle aspiration cytology and tru-cut biopsy from the mass both revealed small round-cell tumour, possibly small cell carcinoma of the lung. However, on immunohistochemistry tumour cells expressed Mic-2 and it was consistent with a diagnosis of primitive neuroectodermal tumour.