Primary proliferative polycythaemia without splenomegaly: a diagnostic problem.

We report three cases of polycythaemia with no evidence of clinical splenomegaly and normal splenic red cell pool on isotope spleen scan. In each case, however, a diagnosis of primary proliferative polycythaemia (PPP) was suggested by in-vitro erythropoietin-independent growth of peripheral blood erythroid colonies. In one of these cases two possible causes of secondary polycythaemia were also identified. The use of investigations such as isotope spleen scanning and erythroid cell culture in helping to establish a diagnosis of PPP is discussed.