Paroxysmal nocturnal hemoglobinuria terminating as erythroleukemia.

A case of a patient who developed erythroleukemia 3 years into the course of paroxysmal nocturnal hemoglobinuria (PNH) is presented. A case of erythroleukemia with a positive sucrose lysis test has been reported, but our case appears to be the first with a long clinical course of PNH evolving into erythroleukemia. The association between these two diseases, their possible clonal origin, and how they fit into the myelodysplastic syndromes are discussed.