Folic-acid Deficiency and Megaloblastic Erythropoiesis in Myelofibrosis.

Folic-acid deficiency may arise in conditions which produce an increased demand for the vitamin. Diseases in this category include acute leukaemia, disseminated carcinomatosis (Girdwood, 1959), myelofibrosis (Chanarin, Mollin, and Anderson, 1958), and haemolytic anaemia (Chanarin, Dacie, and Mollin, 1959). The presence of megaloblastic erythropoiesis in myelofibrosis has been described in only a few cases and is not mentioned in recent reviews of the disease (Leonard, Israils, and Wilkinson, 1957; Bowdler and Prankerd, 1961; Wintrobe, 1961 ; Brit. med. Y., 1963). Chanarin et al. (1958) studied five patients with chronic myelofibrosis, in all of whom there was rapid clearance from the plasma of injected folic acid and in one patient there was a megaloblastic bone-marrow picture. The occurrence of megaloblastic erythropoiesis due to vitamin-B12 deficiency has also been described in three patients with myelofibrosis (Croft, 1956; Baikie, Cunningham, and McAlpine, 1958; Wellington and Whitcomb, 1960). We describe here three cases of myelofibrosis in which there was megaloblastic erythropoiesis produced by folic-acid deficiency. One of these patients developed polycythaemia after receiving treatment with folic acid and iron.