Biochemical abnormalities in chronic erythraemic myelosis.

For a number of years, considerable interest and much investigation has been directed at a group of disordcrs characterized by refractory niacrocytic anaemia, monocytosis, leukopenia, nicgaloblastoid erythroid liyperplasia of the bone marrow, ineffective erythropoiesis with increased serum iron and decreased plasma iron turnover, and in some instances transformation into acute niyeloblastic or myelomonocytic leukaemia. Nomenclature for this group of disorders has varied according to tlie investigators. Historically, Copelli (Copelli, 1912) and subsequently DiGuglielmo (DiGuglielnio, 1933, 1926, 1928) described tlie first accounts of neoplastic erythroid disorders. Today, we recognize these as acute erythraemic myelosis, a rare and almost exclusively erythroid disorder that may be a transitory stage in the evolution of acute niyeloblastic leukaemia (Gunz & Baikie, 1974; Kass & Schnitzer, 197s). Cytochemically, specific esterase granules characteristic of cells of granulocytic origin (Yam ct al, 1971) have been found in erythroid precursors from patients with acute erythraemic myelosis (Kass, 1975a) and erythroleukaemia (Kass, 1976). These findings suggest that the abnormal erythroid precursors found in these two disorders possess properties of granulocytes, and that perhaps these neoplastic erythroid cells may originate from a common myeloblastic stem cell as has been shown in erytliroblasts from patients with chronic erythroleukaemia (McClure et a/, 1965), chronic granulocytic leukaemia (Rastrick et nl, 1968), and ‘preleukaemia’ (Dormer et a / , 1976). Following the more precise description of acute erythraemic myelosis by DiGuglielmo in 1928, descriptions of other erythroid disorders characterized by anaemia refractory to haematinics available at the time began to appear. The concept of iron-loading anaemias was introduced by Israels and Wilkinson who called these types of anaemias ‘achrestic’ (Israels & Wilkinson, 1936). Shortly after the description of achrestic anaemias, it was recognized that there may be a chronic form of erythraemic myelosis (Benedetti, 1939; Duesberg, 1940; Heilmeycr & Schoner, 1941 ; DiGuglielmo & Quattrin, 1942). The idea of a chronic type of erythraemic myelosis appeared to lie dormant for several years following its initial description. Subsequently, reports by several investigators detailed a primary acquired refractory anaemia characterized by increased iron stores and a hallmark of these types of anaemias, tlie ringed sideroblast (Dacie & Mollin, 1966; Bessis, 1973). Various names were given to these entities, including chronic refractory anaemia with sideroblastic bone marrow (Bjorkman, 1956), refractory normoblastic anaemia (Dacie et al, 1959), and refractory sideroblastic anaemia (Heilmeyer et al, 1958). In tlie late 1950s Dameshek attempted to unify these apparent divergent entities by suggesting that they all had common characteristics, including refractory macrocytic anaemia, splenoniegaly, niegaloblastoid erythroid hyperplasia with increased iron stores, and in some instances transformation into acute leukaemia. He suggested that the term ‘DiGuglielmo syndrome’ (Dameshek & Baldini, 1958; Dameshek, 1965, 1969) be used to designate this group of crythroid disorders that seemed to be closely related. These included acute and