Poikilocytosis

Poikilocytosis, an alteration in the shape of red blood cells: instead of the usual round bodies, erythrocytes of irregular pear-shaped or club-shaped form are encountered, with one or many processes, notches, etc. Poikilocytosis is observed, apparently, only in dry blood preparations; in histological preparations, poikilocytosis is absent. This fact indicates that poikilocytosis is not a pre-existing phenomenon, but arises in connection with the instability of erythrocytes revealed upon contact with the external environment. Poikilocytosis has no special diagnostic significance and is observed in anemias of the most diverse character, and in the majority of cases the degree of poikilocytosis runs parallel to the severity of the anemia. Significant poikilocytosis is encountered in chlorosis, as well as in lead poisoning. Poikilocytosis is noted for the most part simultaneously with anisocytosis. Since the time of Ehrlich, it has been assumed that poikilocytosis is caused by a change in the isotonicity of the serum. However, in the origin of poikilocytosis, apart from the indicated factor, the formation in the bone marrow of unstable elements with a disrupted structure and insufficient resistance apparently also plays a role.