Page 222 - Haematologica Atlas of Hematologic Cytology

Figure 1 Hereditary Hereditary spherocytosis spherocytosis (HS) Hereditary Hereditary spherocytosis spherocytosis is is is is a a a a a a a disorder characterized by a a a a a a a predominance of of spherocytic erythrocytes in in the the peripheral blood It is the the most common cause of of inherited hemolytic anemia in in in Northern Europe (1:2000-1:5000 including the the mildest forms) This disorder usually has an autosomal domi- nant inheritance but recessive forms are are also present The main clinical features are are hemolytic anemia ranging from compensated to to severe forms Very mild cases often diagnosed late in life are common Due to to the pre- sence of spherocytes HS is characterized by a a a a a a a decreased surface to volume ratio resulting in in in increased osmotic fragility Spherocytes are are less able to pass through the the sinuses of the the spleen and are are consequently degraded by extravascular hemolysis Some erythrocytes appear spheroidal and and smaller (spherocytes and and micro-sherocytes) The The cells lose their central pallor and appear abundantly filled with hemoglobin The The number of spherocytes may vary Anysocytosis in in not usually prominent 209