Internal Medicine

0521779407-14 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:17

1038 Myeloproliferative Disorders

➣teardrop poikilocytosis with early myeloid forms, nucleated red

cells on the peripheral blood smear

➣bone marrow fibrosis in absence of a secondary cause

JAK2 V617F positive in 50% of IMF

■Essential thrombocythemia

➣exclusion of the above two diseases, exclusion of secondary

causes of high platelets

JAK2 V617F positive in 40% of ET

differential diagnosis

■Polycythemia vera

➣secondary causes of erythrocytosis:

hypoxemia, carbon monoxide, high affinity hemoglobin,

lung disease, pulmonary shunts, sleep apnea, testosterone

excess, polycystic kidney disease, renal cell carcinoma, liver

cysts/tumors, plasma volume contraction

■IMF

➣other causes of myelofibrosis: metastatic carcinoma, infection

(HIV, TB), other hematologic disorders (acute leukemia, CML,

myelodysplasia, hairy cell leukemia), SLE, renal osteodystrophy

Essential thrombocytosis

other causes of thrombocytosis: PV, IMF, iron deficiency,

CML, malignancy, inflammation, post-splenectomy state,

chronic inflammatory conditions

management

What to Do First:

■lower hemoglobin – target males to 14 gm/dl, females to 12 gm/dl

by weekly phlebotomy if necessary

■exclude Philadelphia chromosome by karyotype or PCR in cases of

idiopathic myelofibrosis or essential thrombocythemia

specific therapy

Indications for treatment

■PV

➣control red cell mass via phlebotomy, hydroxyurea, or interferon

➣pruritys may respond to antihistamines, interferon or hydrea

➣low-dose aspirin for thromboprophylaxis

■IMF

➣supportive care

➣consider hydrea, splenectomy or splenic irradiation for symp-

tomatic splenomegaly

➣thalidomide and prednisone, or erythropoietin trials for anemia