Chronic Myeloid Neoplasms
Myelodysplastic syndromes
Refractory anemia with ringed sideroblasts

Author: Nikhil Sangle, M.D. (see Authors page)

Revised: 2 March 2017, last major update August 2011

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PubMed Search: Refractory anemia ringed sideroblasts

Cite this page: Refractory anemia with ringed sideroblasts. PathologyOutlines.com website. http://pathologyoutlines.com/topic/myeloproliferativeRARS.html. Accessed May 23rd, 2017.
Definition / general
  • Also called idiopathic acquired sideroblastic anemia
Diagnosis
  • Ringed sideroblasts detected with iron (Prussian blue) stain represent at least 15% of bone marrow erythroblasts
  • Iron accumulates in mitochondria of erythroid precursors
Laboratory
  • Commonly normochromic macrocytic or normochromic normocytic anemia (hemoglobin usually is < 10 g/dL), usually no other cytopenias but rarely may have thrombocytosis
Case reports
Microscopic (histologic) description
  • Peripheral blood: two RBC populations normal and microcytic hypochromic; occasional coarse basophilic stippling and Pappenheimer bodies; no dysplastic changes, minimal neutropenia, no myeloblasts, no monocytosis, no thrombocytopenia
  • Bone marrow general: hypercellular or normocellular marrow with erythroid hyperplasia
  • Bone marrow erythroid: erythroid hyperplasia, may be mild to moderate dysplasia; markedly increased iron stores, ringed sideroblasts ≥ 15% of marrow erythroblasts, identify with iron stain on marrow smear, has nucleus completely or partially (at least one third circumference) encircled by iron granules
  • Bone marrow myeloid: myeloblasts < 5% (or call RAEB), no dysplasia
  • Bone marrow megakaryocytes: no dysplasia
Microscopic (histologic) images

Images hosted on PathOut server:

Peripheral blood:

Red blood cells are dimorphic
with normochromic and markedly hypochromic cells



Bone marrow smear:

Prussian blue stain shows most red blood cell
precursors are encircled by small granules of iron



Images hosted on other servers:

Bone marrow smear:

RARS with thrombocythemia

Fig 1: peripheral blood shows dual population of microcytic and normocytic red cells with marked poikilocytosis
Fig 2: bone marrow smear shows marked erythroid hyperplasia with many erythroid precursors having megaloblastoid maturation or nucleocytoplasmic asynchrony
Fig 3: iron stain shows numerous ringed sideroblasts (perinuclear iron granules encircle more than 1/3 of nuclear circumference)
Fig 4: transmission EM shows nonspecific siderosomes (black arrow) and iron laden mitochondria (white arrow)

Electron microscopy description
  • Perinuclear iron present in mitochondrial cristae
Electron microscopy images

Images hosted on PathOut server:

Erythroid precursor
shows iron deposits
in mitochondrial cristae

Molecular / cytogenetics description
Differential diagnosis
  • Chloramphenicol or TB drug (isoniazid) exposure, copper deficiency, alcohol or chronic lead poisoning, excess zinc administration
  • Congenital (hereditary x-linked) sideroblastic anemia: causes decrease in the end product of porphyrin synthesis (protoporphyrin IX)
  • Refractory cytopenia with multilineage dysplasia: may have 15% + ringed sideroblasts but also dysplastic changes in 2 or 3 lineages