To the Editor.—
There has been considerable recent interest in studying patients with leukemic transformation of essential thrombocythemia (ET).1,2 It is difficult to know the incidence of such malignant change, since many patients with ET are not hospitalized and are not reported to a central registry. Nevertheless, some idea of relative incidence is available from an exhaustive review of all adult patients with nonlymphocytic leukemia in the entire community of Rochester, NY (population, 241,741; 1980 US census).3 There were 277 cases diagnosed from January 1975 to February 1982. Eleven patients had a myeloproliferative disorder (other than chronic myelogenous leukemia) predating the development of leukemia. Two had ET, two had myeloid metaplasia, and seven had polycythemia vera (PV) (Table).
Report of Cases.—Case 1.—
A 72-year-old man had several episodes of transient numbness and weakness of the left arm and leg that resolved spontaneously. His hemoglobin level was
Boros L, Markham RE, Brennan JK. Primary Thrombocythemia and Acute Leukemia. JAMA. 1985;253(12):1721-1722. doi:10.1001/jama.1985.03350360047010