Pathoma White Blood Cell Disorders Flashcards
What count defines Leukopenia vs Leukocytosis?
Leukopenia - WBC count <5k
Leukocytosis - WBC count >10k
What effect does excess cortisol have on leukocyte count and why?
Causes neutrophilia -> downregulation of P-selectin so they can’t exit tissues
Lymphopenia -> induces apoptosis of lymphocytes
What is the most sensitive cell in the body to whole body radiation?
Lymphocytes
What marker will be decresaed on neutrophils during a left shift?
Immature neutrophils have impaired expression of CD16
- > CD16 = Fc receptor.
- > Don’t function as well for phagocytosis and antibody-dependent cell meated cytotoxicity
- > also present on NK cells
What bacteria causes a lymphocytic leukocytosis and how does it cause this?
Bordetella pertussis
- > produces lymphocytosis-promoting factor
- > blocks circulating lymphocytes from leaving the blood and entering the lymph node
What part of the spleen and lymph node are enlarged in Infectious Mononucleosis?
Spleen - PALS
Lymph node - Paracortex
Due to increased reactive population of CD8+ T cells
Why are patients with HBV at increased risk of B cell lymphoma throughout their life?
The virus lays dormant in the B cells.
-> can reactivate in AIDS patients and predispose to B cell lymphoma, especially in the CNS
What is the most critical marker for ALL? Who tends to get it?
TdT+ - Terminal deoxynucleotidyl transferase - a DNA polymerase
-> not present in mature lymphocytes or the myeloid line
Tends to occur in children, or in Down syndrome patients >5.
What is the most common subtype of ALL and what markers are expressed?
B-ALL
CD10!!!!!!! (not a T cell marker),CD19,CD20
Where must chemotherapy by given for ALL?
Requires prophylaxis to CNS and scrotum - immunoprivileged areas
What cytogenetic markers indicate good and poor prognosis for B-ALL? What populations are they seen in?
Good -> t(12;21) - seen in children
Poor -> t(9;22) - similar to CML, but this one is 190 kD. Seen in adults
Who gets T-ALL?
Disease of T’s
Teenagers
Thymic mass - Lymphoma
T-cell ALL
What leukemias are associated with Down syndrome and at what ages?
Before age 5: Acute megakaryoblastic anemia (type of AML)
After age 5: Acute lymphoblastic leukemia (ALL)
What tissue infiltration is characteristic of acute monocytic leukemia?
Gingival hypertrophy -> monoblasts have a tropism for the gums
Keep in mind this is a type of AML
What is the most common acute leukemia in adults and what are the risk factors?
Acute myeloid leukemia (AML)
- Down syndrome
- Radiation and alkylating chemotherapy -> myelodysplastic syndromes
- Myeloproliferative disorders
What must be seen in bone marrow for diagnosis of MDS?
Hypercellular, abnormal maturation of cells, increased blasts (<20%, or would be leukemia)
Evidence of dysplasia in one or more cell lineages, affecting >10% of cells
What is seen on peripheral blood smear of MDS in general?
Cytopenias - with variable reduction RBCs, platelets, and granulocytes, some with functional defects.
RBCs = normocytic or **macrocytic** WBCs = abnormal nuclear lobation and granules with impaired killing activity
What is one commonly tested WBC anomaly seen in peripheral smear in MDS?
Pseudo-Pelger-Huet anomaly
- neutrophils with bilobed nuclei, and hypogranularity
- will have impaired killing activity
Who tends to get chronic lymphoid leukemias and what are the most typical clinical features?
Older adults, diseases have indolent course (except ATLL)
Lymphadenopathy, hepatosplenomegaly (like ALL)
Constitutional symptoms - fever, night sweats, weight loss, fatigue
Abnormal CBC with bone marrow infiltration
What is the most common leukemia and what type of cell is it overall? Who gets it? What are the flow cytometry markers?
CLL - always older adults
Phenotype by flow cytometry:
CD19+,CD20+ (B-cell), CD5+ (T cell marker)
-> these are naive B cells which co-express B and T cell markers
What is the cell morphology of chronic lymphocytic leukemia (CLL)?
- Small, mature-looking lymphocytes indistinguishable from normal
- Smudge cells - ruptured lymphocytes (cells are fragile in CLL) CLL = crushed little lymphocytes
What is the most common cause of death in CLL? What does this do to blood counts as well?
Infections due to hypogammaglobulinemia - neoplastic B cells do not want to produce useful antibody
If they do, often causes autoimmune hemolytic anemia (leads to thrombocytopenia (Evan’s syndrome) and anemia) -> usually a Warm (IgG), but rarely Cold (IgM)
What is Richter’s syndrome / transformation?
Transformation of SLL / CLL into an aggressive lymphoma, most commonly a diffuse large B-cell lymphoma
Why does CLL cause generalized lymphadenopathy?
Small Lymphocytic Lymphoma is the sister disease. obviously these mature B cells are going to hone into lymph nodes..
What are the lab staining features of hairy cell leukemia? How do they look on peripheral smear? What is the mnemonic?
Mature B cells with hairy cytoplasmic processes (appear fuzzy on LM with indistinct borders)
Lab features - TRAP + (tartrate resistant acid phosphatase)
Remember these hairy cells are TRAPPED in the bone marrow (causing fibrosis) and TRAPPED in the red pulp causing splenomegaly
What will physical exam and CBC show with HCL? Why do these things happen? Will there be lymphadenopathy?
Massive splenomegaly due to accumulation of hairy cells in red pulp
NO lymphadenopathy -> cells are TRAPPED in the bone marrow and cannot make it to LN’s
Pancytopenia will be the rule
-> due to massive fibrosis of bone marrow
What two drugs are used in the treatment of hairy cell leukemia and what is their mechanisms of action?
Cladribine, pentostatin
Both are purine analogs.
Cladribine accumulates due to resistance to adenosine deaminase and prevents DNA polymerase activity
Pentostatin inhibits of adenosine deaminase
-> adenosine toxically accumulates in neoplastic B cells
What is the presentation of Adult T-cell leukemia/lymphoma? Where is it most common?
Most common in Caribbean and Japan (endemic areas)
A diffuse erythematous rash due to skin infiltration, generalized lymphadenopathy with hepatosplenomegaly
-> these T cell lymphomas love to go to skin
What can Adult T cell leukemia/lymphoma be easily confused with and how do you differentiate?
Easily confused with multiple myeloma, since it also causes lytic bone lesions and hypercalcemia
-> differentiate based on presence of rash
What cells are seen in Mycosis fungoides and what is the characteristic intraepidermal finding?
CD4+ T cells with “cerebriform” nuclei
- > this is cutaneous T cell lymphoma (CD4 cells love to go to the skin, like ATLL)
- > Pautrier microabscesses (P doesn’t go with P)
What is Sezary syndrome?
Progression of mycosis fungoides to T cell leukemia -> sezary cells in blood.
Will lead to generalized erythroderma / exfoliative dermatitis
What are the features of CML on peripheral smear and bone marrow CML? What will happen to RBCs and platelets?
Uncontrolled production of ALL granulocytes; remember this is the characteristic disorder where basophils are increased
RBCs -> generally anemia because bone marrow is hypercellular
Platelets -> develop okay -> thrombocytosis