CASE PRESENTATION: A 40 year old Caucasian female presented with dry cough since one year. Over the previous two days, she developed fevers, night sweats and sputum production. She was a lifetime non-smoker. She was previously treated with bronchodilators and steroids for a presumptive diagnosis of asthma. Chest x-ray revealed a 13 * 7 cm anterior mediastinal mass. Subsequent CT chest revealed an 11 * 7.7 cm left anterior mediastinal mass suspicious for lymphoma. CT-guided biopsy of the mass was negative for malignancy. Upon further review the mass was diagnosed as collapsed left upper lobe. Bronchoscopy revealed a smooth vascular endobronchial mass occluding the left upper lobe. Biopsy of the mass revealed ACC. Subsequent PET-CT scan revealed a large hypermetabolic mass in the medial left upper lobe, invading the anterior mediastinum and extending towards the hilum. She was discharged home with antibiotics for post-obstructive pneumonia and surgical followup.