title: Low blast count myeloid disorders with Auer rods: a clinicopathologic analysis of 9 cases.
abstract: Auer rods are a hallmark of acute myeloid leukemia but occasionally are seen in myelodysplastic syndromes (MDSs) or chronic myelomonocytic leukemia, rarely in cases with fewer than 5% blasts. The significance of this finding is unclear. We report 9 cases of this unusual phenomenon. All patients had cytopenias, isolated to a single lineage in 4. Circulating blasts were present in 8 cases (rare to 2.5%). Bone marrow blasts ranged from 0.4 to 4.9%; 1% to 32% of blasts contained Auer rods. There were variable degrees of dysplasia; 1 case closely mimicked refractory anemia with ringed sideroblasts. Cytogenetic studies in 8 cases showed clonal changes in 4. In 5 patients, acute myelogenous leukemia (AML) developed 6, 6, 5, 13, and 24 months after diagnosis; the patients subsequently died. Three patients died at 1, 1, and 8 months without progression to AML, and only 1 was alive at 10 months. MDSs with fewer than 5% blasts and Auer rods seem to be a heterogeneous group, but rapid progression to death or AML in most cases suggests that Auer rods signify an aggressive biology in MDSs with a low blast count.
authors.affiliation: Department of Pathology, University of Texas Southwestern Medical Center, Dallas, USA.
authors.forename: Monte S
authors.initials: MS
authors.lastname: Willis
authors.forename: Robert W
authors.initials: RW
authors.lastname: McKenna
authors.forename: LoAnn C
authors.initials: LC
authors.lastname: Peterson
authors.forename: James E
authors.initials: JE
authors.lastname: Coad
authors.forename: Steven H
authors.initials: SH
authors.lastname: Kroft
mesh_terms: D000368:Aged; D001853:Bone Marrow / Q000473:pathology*; D002648:Child; D003582:Cytogenetics; D005260:Female; D006098:Granulocytes / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009190:Myelodysplastic Syndromes / Q000145:classification / Q000235:genetics / Q000473:pathology*; D011379:Prognosis