Idiopathic Pulmonary Hemosiderosis

William L. Ring

ETIOLOGY

Idiopathic pulmonary hemosiderosis (IPH) is a rare disease of unclear etiology and pathogenesis characterized by the abnormal collection of hemosiderin in the lungs. It is primarily a disease of the first decade of life, but may be diagnosed in adults. Equal gender distribution is seen, and at least some cases seem to have a genetic predisposition. A number of reports have noted an association between celiac disease and IPH, and in some cases, treatment of the celiac disease seemed to improve the course of the IPH. However, a pathogenetic link between celiac disease and IPH remains controversial. Some reports have suggested that IPH may be associated with low socioeconomic status, toxic exposure (insecticides, hydrocarbons), seasonal clustering (spring and fall), viral agents, or diet (cow’s milk allergy). Exacerbations of IPH have been reported with and after pregnancy. Despite these associations, the etiology of IPH remains obscure.

PRESENTATION

The presentation of IPH is highly variable. Iron-deficiency anemia and recurrent or chronic pulmonary symptoms (e.g., cough, hemoptysis, and dyspnea) characterize IPH. Patients may present with hemoptysis, which tends to be episodic. Although hemoptysis can be massive, it is often mild and can be absent despite significant intrapulmonary bleeding. Intrapulmonary bleeding may initially be clinically silent. Iron-deficiency anemia can overshadow clinical or roentgenographic pulmonary abnormalities. Chronic cough, fatigue, dyspnea, and pallor are frequent. Occasionally, pulmonary hypertension develops.

DIAGNOSIS

The diagnosis of IPH is one of exclusion and generally requires ruling out coagulopathy, hemodynamic abnormalities (congestive heart failure, mitral stenosis), and infection, as well as systemic disorders such as vasculitis, immune-complex disease, or antibasement membrane antibody disease.

CLINICAL FINDINGS

Chest radiographs in IPH are generally abnormal and demonstrate diffuse parenchymal infiltrates. At the time of acute hemorrhage, chest radiographs may show diffuse mottled densities, which are particularly prominent in the perihilar regions and lower lung fields. After 2 to 3 days, consolidation is replaced by a reticular pattern that resolves over 10 to 14 days. With repeated bleeding episodes, progressive interstitial changes can develop into a pattern of interstitial fibrosis, which can become massive. Hilar lymph nodes may be enlarged, particularly during acute episodes. Computed tomography (CT) findings confirm the chest roentgenogram findings. Magnetic resonance imaging may specifically diagnose a new hemorrhage because of the paramagnetic effect of ferric iron. Pulmonary function studies show a restrictive pattern, with elevation of the carbon monoxide diffusing capacity during an episode of bleeding. A transient obstructive component also may be present.

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