Hematogenous neoplasms

Topic Completed: 1 August 2013

Minor changes: 1 April 2020

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PubMed Search: Myelodysplasia spleen

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Cite this page: Mansouri J. Myelodysplasia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/spleenmyelodysplasia.html. Accessed May 29th, 2020.
Definition / general
  • Bone marrow disorders with dysplastic changes in at least one myeloid cell line; variable myeloblasts in bone marrow and peripheral blood; due to ineffective bone marrow hematopoiesis with bone marrow hypercellularity but diminished peripheral counts
  • Typically older adults, median age 70 years
  • Males > females
  • Dyspoiesis of hematologic cells observed in peripheral blood, bone marrow, spleen, sometimes lymph nodes
  • Hematopoietic stem cell disorder with associated dysmaturation and maturation arrest in one or more hematopoietic cell lineages
  • De novo (primary) myelodysplasia (MDS): no known history of chemotherapy or radiation treatment
    • Risk factors include increased exposure to benzene, pesticides, organic solvents
    • Also inherited hematological conditions (e.g. Fanconi anemia, Diamond-Blackfan syndrome)
  • Therapy related MDS: history of chemotherapy or radiotherapy
Clinical features
  • Usually present with cytopenias, including anemia, thrombocytopenia, sometimes neutropenia
  • Symptoms may include weakness, fatigue, increased bruising, increased infections
  • Usually no splenomegaly (Am J Surg Pathol 1998;22:1255)
  • Usually based on bone marrow biopsy, peripheral blood smear, cytogenetics / FISH, flow cytometry, CBC
  • Dysplastic forms must be present in one or more hematopoietic cell lineages, with blast count < 20% (or would be AML)
  • Diagnosis of exclusion - must rule out other causes of dysplasia including infections (e.g. HIV, parvovirus) and drugs
  • Rarely, MDS is diagnosed in spleen without diagnostic findings in bone marrow / peripheral blood (e.g. extramedullary hematopoiesis)
Prognostic factors
  • Patient age (< age 60 have better prognosis), number of cytopenias, morphologic subtype of MDS, cytogenetic findings
  • Three risk categories based on morphologic subtype:
    • Low risk: refractory anemia with ringed sideroblasts (RARS), refractory cytopenias with unilineage dysplasia (RCUD)
    • Intermediate risk: refractory cytopenia with multilineage dysplasia (RCMD), refractory cytopenia with excess blasts-1 (RAEB-1)
    • High risk: refractory anemia with excess blasts-2 (RAEB-2)
  • See cytogenetics section
Case reports
  • Often supportive with transfusions for anemia, platelets for severe symptomatic thrombocytopenia
  • Hypomethylating agents such as azaciditine have some survival benefit in intermediate risk MDS
  • May need bone marrow / stem cell transplant for aggressive or refractory cases (Curr Opin Hematol 2013;20:137)
  • Splenectomy rarely performed
  • Iron chelating therapy for iron overload in transfusion dependent MDS
Microscopic (histologic) description
  • Variable erythrophagocytosis, red pulp plasmacytosis, extramedullary hematopoiesis, monocyte clusters
Microscopic (histologic) images

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Erythroid karyorrhexis

Dysmegakaryo-poiesis with hypolobated megakaryocytes

Cytology description
  • Dyserythropoietic forms may exhibit irregular nuclear contours, karyorrhexis, megaloblastoid changes and nuclear budding
  • Ringed sideroblasts; micromegakaryocytes with hypolobation
  • Dysplastic neutrophils show hypogranularity, hypolobation (pseudo-Pelger-Huët forms), irregular hypersegmentation, pseudo-Chédiak-Higashi granules
Positive stains
Flow cytometry description
  • Used to determine number of blasts (CD34+ or CD117+ cells) and CD71+, CD105+ and glycophorin A+ cells in MDS with abnormal erythroid forms
Molecular / cytogenetics description
  • May have prognostic significance:
    • Favorable: MDS with isolated del(5q) common in women; also associated with hypolobated megakaryocytes, refractory anemia, variable increased platelet count
    • Unfavorable: MDS with 17p-; associated with pseudo-Pelger-Huët anomaly, p53 mutation, previous chemotherapy / radiotherapy
    • Unfavorable: MDS with complex karyotypes (3+ abnormalities, often involving chromosome 5 or 7)
Differential diagnosis
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