White Blood Cell Disorders Flashcards
What is the surface marker for hematopoietic stem cells?
CD34+
What is a normal WBC count?
Low?
High?
A normal white blood cell (WBC) count is approximately 5-10 K/uL.
- A low WBC count(< 5 K) is called leukopenia.
- A high WBC count (> 10 K) is called leukocytosis.
- A low or high WBC count is usually due to a decrease or increase in one particular cell lineage.
What is Leukopenia?
Low neutrophils and/or lymphocytes
Neutropenia
What causes it?
How can it be treated?
refers to a decreased number of circulating neutrophils.
Causes include
-
Drug toxicity (e.g., chemotherapy with alkylating agents)-Damage to stem cells
results in decreased production ofWBCs, especially neutrophils. -
Severe infection (e.g., gram-negative sepsis)- Increased movement of neutrophils
into tissues results in decreased circulating neutrophils.
GM-CSF or G-CSF may be used pharmacologically to boost granulocyte production, thereby decreasing risk of infection.
What is Lymphopenia?
Causes?
Lymphopenia refers to a decreased number of circulating lymphocytes.
Causes include
- Immunodeficiency (e.g., DiGeorge syndrome or HIV)
-
High cortisol state (e.g., exogenous corticosteroids or Cushing syndrome)induces
apoptosis of lymphocytes - Autoimmune destruction (e.g., systemic lupus erythematosus)
-
Whole body radiation-Lymphocytes are highly sensitive to radiation;
lymphopenia is the earliest change to emerge after whole body radiation.
What is Neutrophilic Leukocytosis?
$ Name 2 causes
Neutrophilic leukocytosis refers to increased circulating neutrophils.
Causes include
- Bacterial infection or tissue necrosis- induces release of marginated pool and bone marrow neutrophils, including $ immature forms (left shift); immature cells are characterized by decreased Fe receptors (CD16).
- High cortisol state-impairs leukocyte adhesion, leading to release of marginated pool of neutrophils
What is monocytosis
Causes
Monocytosis refers to increased circulating monocytes.
chronic inflammatory states (e.g., autoimmune and infectious) and malignancy
What is Eosinophilia?
$ Which malignancy is this state seen in?
Eosinophilia refers to increased circulating eosinophils. Causes include allergic reactions (type I hypersensitivity), parasitic infections, and
$ Hodgkin lymphoma - Eosinophilia is driven by increased eosinophil chemotactic factor. Increased production of IL-5
$ Which malignant state is basophilia classically seen?
Basophilia refers to increased circulating basophils;
$classically seen in chronic myeloid leukemia
What is Lymphocytic leukocytosis?
$ What is a particularly high yield exception to the rule that neutrophilic leukocytosis is the typical response to bacterial invasion?
Lymphocytic leukocytosis refers to increased circulating lymphocytes. Causes include
-
Viral infections- I lymphocytes undergo hyperplasia in response to virally
infected cells.
2.$ Bordetella pertussis infection-Bacteria produce lymphocytosis-promoting factor, which blocks circulating lymphocytes from leaving the blood to enter the lymph node.
Organs EBV primarily affects
- Oropharynx, resulting in pharyngitis
- Liver, resulting in hepatitis with hepatomegaly and elevated liver enzymes
- B cells
$Which area of the lymph node will be enlarged in EBV infection?
l. Generalized lymphadenopathy (LA D) due to T-cell hyperplasia in the lymph node paracortex
2. **Splenomegaly **due to T-cell hyperplasia in the periarterial lymphatic sheath
An EBV infection may lead to a high WBC and the presence of this type of cell?
High WBC count with atypical lymphocytes (reactive CD8+ T cells) in the blood - large nucleus with abundant cytoplasm, looks like monocyte but actually T-cell.
What test is used to screen for Mono?
What does a negative result suggest?
The monospot test is used for screening.
1. Detects IgM antibodies that cross-react with horse or sheep red blood cells
(heterophile antibodies)
2. Usually turns positive within 1 week after infection
3. A negative monospot test suggests CMV as a possible cause of IM.
4. Definitive diagnosis is made by serologic testing for the EBV viral capsid antigen.
Complicationsof EBV infection?
E. Complications
l. Increased risk for splenic rupture (Fig. 6.3); patients are generally advised to
avoid contact sports for one year.
2. Rash if exposed to ampicillin
3. Dormancy of virus in B cells leads to increased risk for both recurrence and B-cell lymphoma, especially if immunodeficiency (e.g., HIV) develops.
Define Acute Leukemia
What is presentation of patient?
Neoplastic proliferation of blasts; defined as the accumulation of > 20% blasts in the bone marrow.
Increased blasts “crowd-out” normal hematopoiesis, resulting in an
“acute” presentation with anemia (fatigue), thrombocytopenia (bleeding), or neutropen ia
(infection).
How is Acute leukemia subdivided?
Acute leukemia is subdivided into acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML) based on the phenotype of the blasts.
ACUTE LYMPHOBLASTIC LEUKEMIA
Neoplastic accumulation of lymphoblasts (> 20%) in the bone marrow
- Lymphoblasts are characterized by positive nuclear staining for TdT, a DNA polymerase.
- TdT is absent in myeloid blasts and mature lymphocytes.
Which age group commonly gets ALL?
Most commonly arises in children; associated with Down syndrome (usually arises after the age of 5 years)
How is ALL classified? What is most common type?
Subclassified into B-ALL and T-ALL based on surface markers
B-ALL is the most common type of ALL.
How can B-ALL be characterized?
$ What is a consideration that must be accounted for while delivering chemotherapy? Why?
What is the prognosis for B-ALL?
Usually characterized by lymphoblasts (TdT+) that express CDlO, CD19, and CD20.
- Excellent response to chemotherapy; $ requires prophylaxis to scrotum and CSF
- Prognosis is based on cytogenetic abnormalities.
** t(l2;21) has a good prognosi**s; more commonly seen in children
t(9;22)has a poor prognosis; more commonly seen in adults (Philadelphia+ ALL)
How can T-ALL be characterized?
T-ALL is characterized by lymphoblasts (TdT+) that express markers ranging from CD2 to CDS (e.g., CD3, CD4, CD7). The blasts do not express CO10.
Usually presents in teenagers as a mediastinal (thymic) mass (called acute lymphoblastic lymphoma because the malignant cells form a mass) - in mediastinum
A 55 year old presents with general fatigue, weakness, and infections of variable severity with gingival bleeding, epistaxis, and ecchymoses. He also complains of bone pain in his lower legs. A Peripheral blood smear was obtained. The arrow points to a strcuture containing enzymes that perfom an important chemical reaction. What is the enzyme and what reaction does it mediate?
ACUTE MYELOID LEUKEMIA
Neoplastic accumulation of myeloblasts (> 20%) in the bone marrow
Myelobasts are precursors to the granulocytes (Plymorphonuclear leukocytes, Neutrophils, Basophils, Eosinophils)
Myeloblasts are usually characterized by positive cytoplasmic staining for myeloperoxidase (MPO)
1. Crystal aggregates of MPO may be seen as Auer rods
MPO converts H2O2 to HOCl* (bleach)
Neutrophils depend on Oxygen-dependent killing using NADPH oxidase to convert oxygen to an oxygen free radical, then convert it to hydrogen peroxide via superoxide dismutase (SOD), and finally to bleach. Bleach will destroy the phagocytosed microbes.
Peripheral blood with promyelocyte filled with Auer rods in acute promyelocytic leukemia. The neoplastic promyelocyte has numerous splinter-shaped inclusions in the cytoplasm (arrow) representing Auer rods
Age group AML most often arises in?
Types?
Most commonly arises in older adults (average age is 50-60 years)
Subclassified based on cytogenetic abnormalities, lineage of myeloblasts, and surface
markers. High-yield subtypes include:
- Acute promyelocytic leukemia (APL)
- Acute monocytic leukemia
- Acute megakaryoblastic leukemia
$ How is Acute promeyelocitic leukemia (APL) characterized?
Characterized by t(l5;17), which involves translocation of the retinoic acid receptor (RAR) on chromosome 17 to chromosome 15;
RAR disruption blocks maturation and promyelocytes (blasts) accumulate.
$ Treatment for Acute Promyelocytic leukemia? (APL)
$ Treatment is with all-trans-retinoic acid (ATRA, a vitamin A derivative), which binds the altered receptor and causes the blasts to mature (and eventually die).
A derivative of which cell line has likely infiltrated the gingivae?
- *Acute monocytic leukemia (AML)**
i. Proliferation of monoblasts; usually lack MPO
ii. Blasts characteristically infiltrate gums
$ Key association with Acute megakaryoblastic leukemia? (AML)
Acute megakaryoblastic leukemia
i. Proliferation of megakaryoblasts; lack MPO
ii. Associated with Down syndrome (usually arises before the age of 5)
CHRONIC LEUKEMIA
- Neoplastic proliferation of mature circulaling lymphocytes; characterized by a high WBCcount
- Usually insidious in onset and seen in older adults
What is the most common leukemia overall?
CHRONIC LYMPHOCYTIC LEUKEMIA (CLL)
Neoplastic proliferation of naive B cells that co-express CD5(normally on T cellls, now on B) and CD20
What is seen on blood smear with CLL?
Increased lymphocytes and smudge cells (damaged lymphocytes) are seen on blood smear
Involvement of lymph nodes leads to generalized lymphadenopathy and is called small lymphocytic lymphoma.
Complications of CLL?
What is the most common cause of death in CLL?
- *Hypogammaglobulinemia** - lnfection is the most common cause of death in CLL.
2. Autoimmune hemolytic anemia
3. Transformation to diffuse large B-celllymphoma (Richter transformation)marked clinically by an enlarging lymph node or spleen
HAIRY CELL LEUKEMIA
$ What do cells stain positive for?
Neoplastic proliferation of mature B cells characterized by hairy cytoplasmic processes
Cells are positive for tartrate-resistant acid phosphatase (TRAP).
$ Clinical features of this disease?
Hairy Cell Leukemia
Clinical features include $splenomegaly (due to accumulation of hairy cells in red pulp) and “dry tap” on bone marrow aspiration (due to marrow fibrosis).
Lymphadenopathy is usually absent - trapped in spleen!
Peripheral smear from a patient with hairy cell leukemia. Panel A: normal view of five hairy cells. The cells have abundant, irregularly distributed cytoplasm. The nuclei vary from round to oval to slightly lobulated. Panel B: same view but with the contrast adjusted to show the irregular cytoplasmic outlines, giving the cells their “hairy” appearance (arrows). Wright-Giemsa stain.
$ Treatment for Hairy cell Leukemia?
Excellent response to 2-CDA (cladribine), an adenosine deaminase inhibitor; adenosine accumulates to toxic levels in neoplastic B cells.
What is ATLL? What is it associated with?
Features?
A. Neoplastic proliferation of mature CD4+ T cells
R. Associated with HTLV-1; most commonly seen in Japan and the Caribbean
C. Clinical features include rash (skin infiltration), generalized lymphadenopathy with hepatosplenomegaly, and$ lytic (punched-out) bone lesions with hypercalcemia.
MYCOSIS FUNGOIDES
Neoplastic proliferation of mature CD4+ T cells that infiltrate the skin, producing localized skin rash, plaques, and nodules.
Aggregates of neoplastic cells in the epidermis are called $ Pautrier microabscesses.
$ What is a complication of MYCOSIS FUNGOIDES?
Cells can spread to involve the blood, producing Sezary syndrome
Characteristic lymphocytes with $ cerebriform nuclei (Sezary cells) are seen on blood smear
Basic principles of Myeloproliferative disorders?
Age?
Blood panel?
How are they classified?
Complications?
A. Neoplastic proliferation of mature cells of myeloid lineage; disease of late adulthood (average age is 50-60 years)
B. Results in high WBC count with hypercellular bone marrow
- Cells of all myeloid lineages are increased; classified based on the dominant myeloid cell produced
Complications include
- Increased risk for hyperuricemia and gout due to high turnover of cells
- Progression to marrow fibrosis or transformation to acute leukemia
What is CML?
Neoplastic proliferation of mature myeloid cells, especially granulocytes and their precursors; basophils are characteristically increased
Driven by t(9;22) (Philadelphia chromosome) which generates a BCR-ABL fusion protein with increased tyrosine kinase activity.
- First line treatment is imatinib, which blocks tyrosine kinase activity.
Presentation of CML?
What is a complication of CML?
Splenomegaly is common. Enlarging spleen suggests accelerated phase of disease; transformation to acute leukemia usually follows shortly thereafter.
Can transform to $ AML (2/3 of cases) or ALL (1/3 of cases) since mutation is in a pluripotent stem cell.
How would you distinguish CML from a leukemoid reaction?
CML is distinguished from a leukemoid reaction (reactive neutrophilic leukocytosis) by
$ 1. Negative leukocyte alkaline phosphatase (LAP) stain (granulocytes in a leukemoid reaction are LAP positive)
$ 2. Increased basophils (absent with leukemoid reaction)
$ 3. t(9;22) (absent in leukemoid reaction)