Complications The major clinical complications of PV relate directly to the increase in blood viscosity associated with red cell mass elevation and indirectly to the increased turnover of red cells, leukocytes, and platelets with the attendant increase in uric acid and cytokine production. The latter appears to be responsible for the increase in peptic ulcer disease and for the pruritus associated with this disorder, although formal proof for this has not been obtained. A sudden massive increase in spleen size can be associated with splenic infarction or progressive cachexia. Myelofibrosis appears to be part of the natural history of the. | Chapter 103. Polycythemia Vera and Other Myeloproliferative Diseases Part 4 Complications The major clinical complications of PV relate directly to the increase in blood viscosity associated with red cell mass elevation and indirectly to the increased turnover of red cells leukocytes and platelets with the attendant increase in uric acid and cytokine production. The latter appears to be responsible for the increase in peptic ulcer disease and for the pruritus associated with this disorder although formal proof for this has not been obtained. A sudden massive increase in spleen size can be associated with splenic infarction or progressive cachexia. Myelofibrosis appears to be part of the natural history of the disease but is a reactive reversible process that does not itself impede hematopoiesis and by itself has no prognostic significance. In some patients however the myelofibrosis is accompanied by significant extramedullary hematopoiesis hepatosplenomegaly and transfusion-dependent anemia. The organomegaly can cause significant mechanical discomfort portal hypertension and cachexia. Although the incidence of acute nonlymphocytic leukemia is increased in PV the incidence of acute leukemia in patients not exposed to chemotherapy or radiation is low and the development of leukemia is related to older age but not disease duration suggesting that the treatment exposure may be a more important risk factor than the disease itself. Erythromelalgia is a curious syndrome of unknown etiology associated with thrombocytosis primarily involving the lower extremities and manifested usually by erythema warmth and pain of the affected appendage and occasionally digital infarction. It occurs with a variable frequency in myeloproliferative disorder patients and is usually responsive to salicylates. Some of the central nervous system symptoms observed in patients with PV such as ocular migraine may represent a variant of erythromelalgia. If left uncontrolled erythrocytosis can lead
