Idiopathic pulmonary hemosiderosis: A state of the art review.

Idiopathic pulmonary hemosiderosis (IPH) is an uncommon cause of diffuse alveolar hemorrhage (DAH). Patients with IPH usually present with hemoptysis, and the diagnosis is often delayed by years. Patients often present with intermittent episodes of hemoptysis interspersed between periods of relative normalcy. However, massive hemorrhage resulting in acute respiratory failure and non-remitting hemoptysis have also been described. The classic triad includes hemoptysis, radiologic lung infiltrate, and iron deficiency anemia. Several hypotheses regarding the pathogenesis of IPH have been proposed. These risk factors include an autoimmune, allergic or genetic predisposition, and possible environmental exposure. Since IPH appears to be responsive to corticosteroids, the autoimmune hypothesis is considered to play a crucial role. A diagnosis of IPH requires exclusion of other etiologies of DAH, including infection, medications, toxic inhalation, vasculitis, and anti-glomerular basement membrane disease, among others. Histologically, IPH is characterized by the presence of hemosiderin-laden macrophages in the alveolar space without any evidence of vasculitis or immunocomplex deposition. Corticosteroid therapy represents the primary modality of treatment. Other immunosuppressive medications have also been used with varying success, especially in the setting of steroid-refractory disease. The prognosis of IPH in adults is somewhat better compared to the pediatric population. The severity of the initial presentation does not predict future outcomes. Which risk factors and patient characteristics are associated with a poor outcome are also unknown. More research is necessary to elucidate the pathophysiology and appropriate treatment.