Leukopenia - DSA

Question 1

Neutropenia

Answer 1

absolute neutrophil count less than 1500/uL

congenital or acquired

If d/t chemo, marrow failure, or marrow exhaustion - higher rates of infection

Question 2

Primary causes of neutropenia

Answer 2

Ethnic and benign familial (constitutional) neutropenia
Severe congenital neutropenia
Cyclic neutropenia
Shwachman-Diamond syndrome
Fanconi anemia
Dyskeratosis congenita
Glycogen storage dz type Ib
Myeljkathexis
Chediak-Higashi syndrome
Grisella syndrome type II
Herman sky-Pudlak syndrome II
Barth syndrome

Question 3

Secondary causes of neutropenia

Answer 3

Infection
Post infection
Drug induced
Immune neutropenia
Primary bone marrow failure
Margination and hypersplenism
Vit. and mineral deficiencies - B12, folate, copper
chronic idiopathic neutropenia in adults (CINA)

Question 4

Ethnic and Benign Familial (Constitutional) Neutropenia

Answer 4

Constitutional neutropenia - compared to normal range based on young, white individuals

AA, Yemenite Jews, Falasha Jews, African Bedouins

single nt polymorphism in Duffy antigen receptor for chemokine (DARC)

AD - benign familial neutropenia: neutrophil counts 800-1400/uL range

Question 5

Severe Congenital Neutropenia

Answer 5

Severe neutropenia - less than 500/uL
Presents in neonatal period - recurrent bacterial infections first months of life (omphalitis, perirectal abscesses)

Increase other myeloid cell lines - monocytes, eosinophils

Maturation arrest in marrow - absent mature neutrophil elements

Neutrophil elastase (ELA2 or ELANE) - high in promyelocyte stage, packaged in primary granules

• mutations –> defective cellular trafficking, cytoplasmic accumulation triggering apoptosis
• accumulation of mutant elastase in ER activates unfolded protein response –> apoptosis

Hax-1: mt protein like BCL2 - absence leads to mt-dependent apoptosis

AR: Kostmann syndrome

WASP - Wiskott-Aldrich syndrome protein - regulates actin polymerization in hematopoietic cells –> small platelets in low numbers, sinopulmonary infections, eczema
-X linked: thrombocytopenia and neutropenia

Glucose-6-phosphatase catalytic subunit 3 (G6PC3) mutation: homozygous loss –> activation of unfolded protein response, increased apoptosis in neutrophil precursors

Tx: G-CSF allows children to survive; predisposes to myelodysplasia and acute leukemia (MDS/AML) - 2%/yr, 30% over 10 yrs

• higher transformation in refractory or high doses
• acquired mutation of G-CSF receptor:
• —block ligand binding = G-CSF resistant SCN
• — missense mutation- hypersensitivity –> deletion of distal intracellular domain of receptor responsible for differentiation signaling –> proliferation of progenitors at expense of maturation

Question 6

Cyclic Neutropenia

Answer 6

less than 200/uL lasting 3-5 days in 21 day intervals

Recurrent fevers, mouth sores, infections of skin, upper respiratory tract, ears

Congenital: Mutations in neutrophil elastase in all cases

Dx: sequence neutrophil elastase gene

Tx: G-CSF, no increased risk of leukemic transformation

Acquired in adulthood (rare) - assoc. w/ systemic dz - large granular lymphocytosis or T cell lymphoma

Question 7

Shwachman-Diamond syndrome

Answer 7

isolated neutropenia progresses to marrow failure

associated with pancreatic dysfunction and skeletal abnormalities

Shwachman-Bodian-Diamond syndrome gene (SBDS) - regulates rRNA

Increased risk for leukemic tranformation

Question 8

Fanconia anemia

Answer 8

mutations in DNA repair genes - more time for marrow failure to develop (median age 7 yo)

Short stature, upper limb anomalies, cafe au last spots
1/3 no physical abnormalities

Screen:

• chromosomal fragility testing following exposure to diepoxybutane or mitomycin C
• direct assessment for Fanconi gene mutations

Cure: stem cell transplant - high risk for M&M

Question 9

Dyskeratosis congenita (DKC)

Answer 9

nail dystrophy, leukoplakia, skin pigmentation abnormalities
assoc. w/ neutropenia or aplastic anemia or both

AD or AR or X linked

mutations in telomere maintenance –> pulmonary fibrosis, hepatic cirrhosis, bone marrow failure

Presents in 2nd decade of life

Question 10

Glycogen storage disease Ib

Answer 10

AR

intermittent neutropenia d/t defects in neutrophil respiratory burst with subsequent apoptosis of circulating neutrophils

Hepatomegaly and metabolic crises

mutations in glucose-6-phosphatase translocase

Question 11

Myelokathexis

Answer 11

retention of mature neutrophils in marrow despite low peripheral count

Infection: sudden rise in neutrophil count = benign clinical course

WHIM syndrome: warts, hypogammaglobinemia, immunodeficiency, myelokathexis

Question 12

Chediak-Higashi syndrome

Answer 12

mutations in lysosomal trafficking regulator gene (LYST)

oculocutaneous albinism, bleeding, progressive neurologic dz, increased susceptibility to hemophagocytic syndrome

Question 13

Griscelli syndrome II

Answer 13

increased susceptibility to hemophagocytic syndrome

albinism, periodic neutropenia

mutations in guanosine triphosphatase RAB27A - release of myeloperoxidase from primary granules of neutrophils

Question 14

Hermanski-Pudlack syndrome II

Answer 14

mutations in AP3B1 gene

vesicular trafficking, including trafficking of neutrophil elastase

albinism, platelet abnormalities, pulmonary fibrosis

Question 15

Barth syndrome

Answer 15

X linked, AR

Neutropenia, cardiomyopathy, growth retardation

High mortality rate in early childhood - heart dz

TAZ gene mutation - tafazzin protein: critical to remodeling cardiolipin in mt membrane

Question 16

Infection-related neutropenia

Answer 16

Viral infections - transient neutropenia, resolves as viremia abates
-varicella, measles, rubella, HAV, HBV, EBV, influenza, parvovirus, CMV

Redistribution, decreased production, immune destruction of neutrophils

HIV, AIDS - multifactoral leukopenia, neutropenia

splenomegaly with increased sequestration
More commonly: immune-mediated destruction

bacteria causing moderate neutropenia: M. tuberculosis, ehrlichiosis, rickettsia, tularemia, brucellosis, staph

Overwhelming sepsis - consumption of marrow neutrophil reserve - newborns and elderly

Increased margination during sepsis due to systemic activation of compliment - exacerbating neutropenia

Question 17

Drug-induced neutropenia

Answer 17

Most common cause of neutropenia

suppression of marrow granulopoiesis, increased destruction or clearance of peripheral neutrophils

Dose dependent - predictable, mild
Idiosyncratic immune mediated destruction - profound agranulocytosis

Typical pattern: 1-2 weeks of exposure - neutrophil count decline, recovery begins within 1-2 days of stopping drug

Atypical: present long after drug initiation or longer interval before recovery

Acute sepsis - significant risk for acute mortality

Recovery - preceded by appearance of monocytes and immature neutrophil forms
-more hyper cellular marrow is at dx, earlier recovery

Drugs: antineoplastic, antiviral, immunosuppressive agents, clozapine, carbimazole, methimazole, propylthiouracil, quinidine, procainamide, sulfasalazine, Levamisole (cocaine-assoc neutropenia)

Speed recovery with G-CSF

Question 18

neutropenia due to marrow injury

Answer 18

Radiation - acute or chronic marrow failure state

High dose - risk for myelodysplasia and leukemia, which cause marrow failure and marrow fibrosis –> cytopenias

Metastatic carcinoma to bone –> marrow failure, marrow replaced by metastatic cells

Question 19

Primary autoimmune neutropenia

Answer 19

children younger than 4, median onset 6-12 mo

infectious risk increased
-Prophylactic abx; G-CSF only for acute infectious episodes

95% spontaneous remissions within 2 years

Antineutrophil Ab against FcyIIIb - mediate destruction by sequestration in spleen or complement mediated lysis

Question 20

Secondary autoimmune neutropenia

Answer 20

Adults

assoc w/ hyperthyroidism, Wegener granulomatosis, RA, SLE

50% SLE have antineutrophil Ab but may have normal neutrophil counts

Question 21

Felty syndrome and large granular lymphocyte syndrome

Answer 21

Felty: long standing RA, splenomegaly, profound neutropenia; polyclonal

Large granular lymphocyte syndrome: RA or isolated; monoclonal

Both:
proliferation of large granular lymphocytes
CD3+, CD8+, CD16+, CD57+

90% of RA have HLA-DR4+

Immune mediated neutrophil destruction - antineutrophil Ab and cell mediated destruction

Some have G-CSF resistance d/t G-CSF Ab

Question 22

Isoimmune neonatal neutropenia

Answer 22

moderate to severe neutropenia
Newborn - transplacental passage of maternal IgG against alleles inherited from father –> neutropenia similar to Rh hemolytic dz

Question 23

Pure white cell aplasia

Answer 23

rare
assoc w/ severe pyogenic infections, thymoma in 2/3

Following Ibu tx

complete absence of myeloid precursors

Removal of thymoma may not cause remission

Adjuvant tx: cyclophosphamide, corticosteroids, cyclosporine, IV Ig

Question 24

Neutropenia d/t increased margination and hypersplenism

Answer 24

compliment activation –> acute and chronic neutropenia
-increased margination of circulating pool

C5a makes neutrophils more adherent - prone to aggression within pulmonary vasculature

Seen in burn and transfusion reaction patients

Neutrophil destruction in paroxysmal nocturnal hemoglobinuria

Hypersplenism - less common, less pronounced than the anemia and thrombocytopenia associated with enlarged spleen

Question 25

B12, folate, copper deficiencies

Answer 25

Copper deficiency: total parenteral nutrition w/o Cu supplement, protein-losing enteropathies, celiac dz, gastric bypass surgery, postgastrectomy, malabsorption syndromes, zinc toxicity

Low serum Cu and ceruloplasm levels
Hypo granularity and hypolobation (PHA) on smear
Cytoplasmic vacuolization of myeloid and erythroid precursors and ringed sideroblasts

All these deficiencies: ineffective myelopoiesis, maturation arrest, megaloblastic changes with nuclear cytoplasmic dyssynchrony
-megaloblastic anemia, hyper segmentation of neutrophils

Question 26

Chronic idiopathic neutropenia

Answer 26

Adults - acquired disorder of granulopoiesis

prolonged neutropenia in absence of any underlying etiology

incidental finding

heterogenous, wide range of counts
ANC below 200 - generally benign

When very low - tx with G-CSF when develop fever

Recurrent infections or aphthous ulcers require chronic G-CSF tx

Respond to low doses of G-CSF, no increase in MDS/AML development

Greek predisposed: increased TGF-b suppresses granulopoiesis; mild neutropenia, ANC rarely less than 800

Question 27

Diagnostic approach to neutropenia

Answer 27

Fever, localizing signs:
Yes: If ANC less than 500/mL - admit for IV abx, consider G-CSF
No: stop potential drugs, look for toxins

If it is new:
Isolated neutropenia:  bone marrow exam 
-abnormal cytogenetics - myelodysplasia
-LGL by flow - large granular lymphocyte syndrome 
- all normal - idiopathic neutropenia

Pancytopenia:

• check for autoimmune disease, if no bone marrow exam (see above)
• Vitamin levels - B12 low - megaloblastic anemia

Established neutropenia:

• Family history:
• —check ELANE mutation - if present: cyclic neutropenia
• —Appropriate ethnic group - constitutional or familial neutropenia

-No family history: If cyclic, check ELANE mutation