Pulmonary hemosiderosis (PH) is a rare, chronic lung disease characterized by hemoptysis, iron deficiency anemia, and alveolar and/or interstitial opacities on lung imaging. Little about the etiology and pathophysiology of the disease is known, but PH typically involves periods of remission and relapse. New research that investigated the relationships between PH and Down syndrome (DS), and found that patients with DS have a higher risk of developing PH.