Idiopathic Pulmonary Hemosiderosis (IPH)

Idiopathic pulmonary hemosiderosis (IPH) is a rare disorder characterized by recurrent episodes of diffuse alveolar hemorrhage (DAH) without identifiable cause after extensive workup. The pathophysiology remains unclear, but theories include autoimmune mechanisms (HLA-DR association, response to immunosuppression), capillary fragility, allergic component (associated with celiac disease in Lane-Hamilton syndrome), and environmental triggers (premium gasoline exposure historically reported). Capillaritis on biopsy is absent (distinguishing from immune-mediated DAH), with bland alveolar hemorrhage as predominant finding.

Clinical presentation differs by age: children (peak 1-7 years, slight male predominance) often present with insidious anemia (chronic occult bleeding), failure to thrive, fatigue, pallor, with overt hemoptysis less common as children swallow blood. Adults may present with hemoptysis (more often), iron deficiency anemia, dyspnea, and chronic cough. Acute exacerbations cause sudden hemoptysis, dyspnea, hypoxia, and chest pain, with diffuse bilateral pulmonary infiltrates on imaging. Lane-Hamilton syndrome describes the association with celiac disease, where gluten-free diet may improve pulmonary symptoms.

Diagnostic workup requires exclusion of secondary causes: ANCA testing (GPA, MPA, EGPA), anti-GBM antibodies (Goodpasture's), antinuclear antibodies (lupus, SLE), echocardiography (cardiac causes - mitral stenosis, LV dysfunction), coagulation studies, infectious workup, drug history (cocaine, anticoagulants). Bronchoalveolar lavage (BAL) shows progressively bloodier returns and >20% hemosiderin-laden macrophages on Perls' Prussian blue stain. Lung biopsy in unclear cases shows alveolar hemosiderin without capillaritis, vasculitis, or immune deposits. Celiac antibodies (anti-tTG, anti-EMA) and small bowel biopsy if Lane-Hamilton suspected.