Idiopathic Pulmonary Haemosiderosis

Idiopathic pulmonary haemosiderosis has two clinical subsets, those that present in early childhood and others as young adults, most often male. Although some theorize autoimmune mechanisms, the aetiology of this disorder is not clear. It has a more benign course in adults. The process implies some abnormality of the cell lining of the alveolar or bronchiolar capillaries. Spontaneous haemorrhage has been reported in athletes that has a proposed connection with high vascular pressures and flow in the small pulmonary vessels. If the basement membranes are at all abnormal or the vascular walls abnormal, then the threshold for this bleeding might even be lowered to the athletic activity of the average couch potato. The pulmonary venous pressure in idiopathic pulmonary haemosiderosis is normal.

Idiopathic pulmonary haemosiderosis is not usually associated with renal impairment and, unlike Goodpasture's syndrome, there is no proven antibody to the alveolar basement membrane. Recurrent haemorrhage with blood in alveoli and interstitium can cause inward migration of cells with fibrosis of the alveolar septa. Given the accumulation of haemosiderin in the pulmonary interstitium, the nodularity and linear shadowing may be denser than average after recurrent episodes of bleeding.