Idiopathic pulmonary hemosiderosis is a diagnosis of exclusion based on patient presentation with acute, subacute, or recurrent DAH, on the results of lung biopsy showing evidence of 'bland' pulmonary hemorrhage (ie, without capillaritis or vasculitis), and after exclusion of the conditions listed above [189] . In this situation, red blood cells leak into the alveolar space without evidence of damage and/or inflammation of the alveolar capillaries. In addition, the diagnosis of idiopathic pulmonary hemosiderosis can only be considered after exclusion of diseases induced by environmental factors such as pesticide and cow's milk (Heiner's syndrome) [190] . This syndrome is a hypersensitivity disease that affects primarily infants, and is caused by antibodies to cow's milk proteins. The diagnosis is supported by positive milk precipitin test and rapid improvement of symptoms and pulmonary infiltrates on chest imaging after exclusion of milk proteins.