Acute myelomonocytic leukemia and the French-American-British classification.

39 patients suffering from different subtypes of monocytic (M 5) and myelomonocytic (M 4) leukemia were analyzed retrospectively. In 8 cases a 'transitional myelomonocytic variant' was diagnosed; the leukemic cell in these patients is marked by morphological and cytochemical signs of monocytic and granulocytic precursors. As the correct diagnosis of this special subtype may be difficult, its place within the French-American-British (FAB) classification will be discussed.