Aplastic Anemia 9/12/2018

Today our Doctor-in -Training, Emma, presented a case of a middle age woman with no significant medical or family history coming in with a month of fatigue, menorrhagia, and gum bleeding. She was incidentally found to be pan-cytopenic. Bone marrow biopsy revealed hypocellularity with no abnormal morphologies, which is consistent with aplastic anemia!

Aplastic anemia

  • Epidemiology
    • Rare, 2 per million per year, higher incidence amongst Asians, can occur in all ages but most of the time in the first 1st-4th decades.
  • Pathophysiology
    • Big picture: Think of it this way. Aplastic anemia is similar to a factory not working due to not enough workers (stem cells). Compare and contrast this with MDS, which is basically a loss of quality control (mutation in the stem cells) leading to bad products that get worse over time (leading eventually to pancytopenia, leukemia).Capture
      • Causes
        • Primary (rare), most of the time acquired
        • Infectious: CMV, Parvo, EBV, HIV, hepatitis, TB
        • Toxins: Benzene, glue vapors, solvents, pesticides
        • Autoimmune: SLE, eosinophilic fasciitis, graft v host,
        • Other: Pregnancy, paroxysmal nocturnal hemoglobinuria, thymoma, irradiation
        • Medications: NSAIDS, Bactrim, Lasix, Gold, Allopurinol, penicillamine, phenothiazines, AEDS, anti-psychotics
      • Association
        • PNH: CD55 & CD59 abnormalities can be sen in up to 50% of patients with aplastic anemia!
      • Presentation
        • S/S of anemia
        • S/S of thrombocytopenia (menorrhagia, petechiae)
        • Recurrent infections
      • Diagnosis
        • Bone marrow biopsy most definitive, helps distinguish AA from other causes of pancytopenia
        • BM finding
          • Hypocellular, marrow space mostly fat cells and marrow stroma.
          • Remaining cells are morphologically normal
          • No fibrosis, no e/o malignancy
        • Severe AA criteria
          • BM cellularity < 25 + 2 of ANC < 500, plt < 20k, retic < 20k
        • Very Severe AA criteria
          • ANC < 200
        • Mgx: Severe AA require treatment
          • Under age 20: Early allogeneic HCT as soon as possible. If HCT not possible, immunosuppressives
          • 20 – 50: HCT also recommended if no contraindications, immunosuppressives (Anti-thymocyte globulin, cyclosporine for example) + eltrombopag (thrombopoietin agonist) otherwise.
          • > 50:
            • Transplantable: Early hematopoietic cell transplantation
            • Older, not candidates for HCT: Immunosuppressive, less intense preferred as age increases.
          • Treat other underlying/reversible causes in all cases.

Fun Fact: Blood transfusion can lead to falsely elevated iron studies within the first 24-36 hours.

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