Cough is one of the most common presenting complaints encountered in primary care settings and the emergency department. In 2010, the Centers for Disease Control and Prevention reported approximately 31 million visits to ambulatory care centers for cough, making cough the most frequent presenting complaint in ambulatory visits (2010 National Ambulatory Medical Care Survey). Significant causes of cough can often be overlooked because it is a common symptom of a myriad of pathologies. We report the case of an otherwise healthy 9-year-old male who presented with worsening cough over a month and a half, subsequently noted to have a mediastinal mass, and diagnosed with lymphoma. We discuss the challenges of diagnosing life-threatening pathologies, which present with common symptoms.