Male, 54 years old, with smoking habits. The patient complaints were cough, with bleeding secretions in the previous two months. Because of the persistence of the symptoms, a bronchoscopy was proposed. This exam showed multiple lesions in the trachea, nearly 2 cm above the vocal cords that compromised the airway and did not allow the progression of the bronchoscope. For this reason, it was decided to introduce a tracheal prosthesis. Because of instability, and the suspicion of malignancy we started thoracic irradiation. The histological specimen was compatible with anaplastic Lymphoma, CD 30+. Because of respiratory distress, with stridor, the prosthesis was removed. The trachea was permeable after this. The patient was discharged and oriented to Clinical Haematology. He is clinically stable and under monitoring, having now completed a chemotherapy treatment with CHOP (Ciclophosphamide, Adriamycin or Hydroxydorubicin, Vincristine or Oncovin and Prednisone). The primary mediastinal Large Cells Lymphoma represents 11.5% of the Large Cells Lymphomas (2% of the non-Hodgkin's Lymphomas). This neoplasm is in many studies considered incurable, but there are some positive results with the combination of radiotherapy and chemotherapy. If there is any airway compromise, the tracheal prosthesis may be one option for the resolution of the respiratory insufficiency.