hemosiderose

Hemosiderose refers to the abnormal accumulation of hemosiderin, an iron-storage pigment, in tissues. It results from increased iron deposition or leakage of blood into tissues, leading to iron overload in organs over time. The term is often used to describe secondary iron overload as opposed to primary iron overload disorders like hereditary hemochromatosis.

The condition is classified as primary or secondary. Primary hemosiderosis includes genetic or acquired disorders that predispose to excessive iron absorption or storage, such as hereditary or familial hemochromatosis. Secondary hemosiderosis commonly arises from repeated blood transfusions, chronic hemolysis, or ineffective erythropoiesis (as seen in certain anemias and myelodysplastic syndromes). Pulmonary hemosiderosis is a related form where bleeding into the alveoli leads to deposition of iron as hemosiderin, detectable as hemosiderin-laden macrophages.

Pathophysiologically, macrophages ingest erythrocytes or free iron and store iron as ferritin and, upon excess, as hemosiderin. Accumulated iron can damage tissues through oxidative stress and promote organ dysfunction. Commonly affected sites include the liver, heart, endocrine glands, and lungs, with clinical consequences depending on the organs involved.

Diagnosis involves clinical context, iron studies (ferritin levels, transferrin saturation), imaging (MRI to quantify iron deposition, especially in the liver), and tissue assessment when indicated (liver biopsy with Prussian blue staining; bronchoalveolar lavage showing hemosiderin-laden macrophages in pulmonary involvement).

Treatment targets the underlying cause and iron burden. Phlebotomy is first-line for hereditary iron overload; iron chelation therapy (deferoxamine, deferasirox, deferiprone) is used when phlebotomy is unsuitable or in transfusional iron overload. Monitoring and management of organ complications are essential. Prognosis varies with etiology, extent of iron deposition, and response to therapy.