[Abundant erythroblastic islands in bone marrow aspirate in a case of polycythemia vera. Various considerations on this anatomo-functional structure].

Despite the initial description, more than 30 years ago, of an erythroblastic island (EI), little is known about the mechanisms of union and interaction between the different cells of this anatomical and functional bone marrow structure. The observation of entire Els is extremely uncommon in normal bone marrow aspirates because of their dispersion during spread. A case report is described in which a 73-year-old woman, diagnosed 20 years ago with polycythaemia vera, showed multiple Els in a bone marrow aspirate. Their immunophenotyping revealed deficiency of several integrins. The ultrastructural study indicated a marked erythroblastic rophalocytosis. A hypothesis is suggested in view of these observations.