The Collaborative International Dictionary of English v.0.48:

hemosiderosis \hemosiderosis\ n. (Med.)
   The accumulation of abnormal amounts of hemosiderin in the
   tisssues. Several causes have been recognized. --Stedman.
   [PJC]

WordNet (r) 3.0 (2006):

hemosiderosis
    n 1: abnormal deposit of hemosiderin; often a symptom of
         thalassemia or hemochromatosis [syn: hemosiderosis,
         haemosiderosis]