title: Acute monocytic leukemia with chloroacetate esterase positivity. FAB M4 or M5?
abstract: French-American-British criteria for the diagnosis of acute monocytic leukemia (M5) require that 80% of nonerythroid bone marrow cells consist of monoblasts, promonocytes, and/or monocytes. Monocytic differentiation is demonstrated by fluoride-sensitive nonspecific esterase positivity. Chloroacetate esterase positivity is accepted as a marker of granulocytic differentiation. Three cases fulfilling French-American-British criteria for M5 showed fluoride-sensitive nonspecific esterase positivity in up to 100% of nonerythroid marrow cells but also exhibited strong chloroacetate esterase positivity in 20% to 90% of the same population. Less than 5% of blasts stained for Sudan black B and peroxidase. These cases may be viewed as chloroacetic esterase-positive acute monocytic leukemia or as acute myelomonocytic leukemia. The authors favor the former because the cases were myeloperoxidase negative; however, these cases indicate that chloroacetate esterase may not be a specific marker for granulocytic differentiation.
authors.affiliation: Institute of Pathology, Case Western Reserve University, Cleveland, Ohio.
authors.forename: N S
authors.initials: NS
authors.lastname: Rosenthal
authors.forename: D C
authors.initials: DC
authors.lastname: Farhi
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001853:Bone Marrow / Q000737:chemistry / Q000473:pathology / Q000648:ultrastructure; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D007948:Leukemia, Monocytic, Acute / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged
chemical_list: D002265:Carboxylic Ester Hydrolases; C019873:chloroacetate esterase