Chapter 13- WBCs, Lymph Nodes, Spleen And Thymus Flashcards
What are the two divisions of blood cell types?
Myeloid (bone marrow)
Lymphoid (thymus, lymph nodes, spleen)
What is leukopenia?
WBC deficiency
What is the most common type of leukopenia?
Neutropenia
What are the possible causes of neutropenia?
Inadequate/ineffective granulopoiesis
Increased cell destruction or removal in the periphery
What state does hypocellularity occur in?
Suppression of granulocyte progenitor cell growth and survival
What state(s) does hypercellularity occur in?
Ineffective granulopoiesis or increased peripheral destruction
What are the clinical features of neutropenia?
Ulcerating, necrotizing lesions of the oral mucosa
Ulcerative lesions of the skin, vagina, anus or GI tract are less common
Life threatening infections (compromised immune system)
What is leukocytosis?
Increased proliferation of WBC
What are the two types of leukocytosis?
- Reactive
2. Neoplastic
What are potential causes of reactive leukocytosis?
Increased marrow production
Increased release from stores
Decreased margination
Decreased extravasation
What are the types of reactive leukocytosis and their causes?
Neutrophilia- acute bacterial infections
Eosinophilia- allergies, parasitic infections
Basophilia- myeloproliferative disease
Monocytosis- chronic infections, autoimmune
Lymphocytosis- chronic infections, viral infections
What is lymphadenitis?
Lymph node infection
How can lymphadenitis contribute to reactive leukocytosis?
Activation causes hyperplasia of follicles and paracortex (increased lymphocyte production and release)
What are the different types of lymphadenitis?
Acute nonspecific- tender, localized or systemic
Chronic nonspecific- nontender, follicular or paracortical hyperplasia
Hemophagocytic lymphohistiocytosis- activated macs engulf other blood cell elements, cytokine storm (inflammatory response)
What cells are associated with which part of the lymph node?
T-cells- paracortex
B-cells- follicles
What is sinus histiocytosis?
Macrophages aggregate within sinuses of lymph nodes draining tissue with epithelial cancers (eg. breast)
What etiological and pathogenic factors influence neoplastic leukocytosis?
Chromosomal translocations and other mutations
Genetic factors
Viruses
Chronic inflammation
Iatrogenic factors and smoking
What is the difference between leukemias and lymphoma?
Leukemia- BM and blood cells
Lymphoma- discrete tissue masses
What are the categories of neoplastic leukocytosis?
Precursor B-cell
Peripheral B-cell
Precursor T-cell
Peripheral T-cell
Hodgkin lymphoma
What is the difference between precursor and peripheral lymphoid neoplasms?
Precursor- immature
Peripheral- mature
What are the peripheral B-cell neoplasms?
Peripheral B-cell (CLL)
Follicular lymphoma
Diffuse large B-cell lymphoma (DLBCL)
Burkitt lymphoma
Plasma cell neoplasm
Lymphoplasmacytic lymphoma
Mantle cell lymphoma
Marginal zone lymphoma
Hairy cell leukemia
What type of leukemia/lymphoma characterizes precursor B and T-cell neoplasms?
Acute lymphoblastic (ALL)
What are the characteristics of ALL?
Most common childhood leukemia
Lymphoblasts fill marrow (depressed function)
Anemia, infections, bleeding
Bone pain
CNS manifestations
Lymphadenopathy, hepatosplenomegaly, testicular enlargement
How does pre-T ALL present in adolescent boys?
Thymic lymphoma
What are the characteristics of CLL?
Median age 60
More common in men
Lymph >5000 cells/uL
Transformation common
What is another name for CLL?
Small lymphocytic lymphoma
What is the most common adult leukemia?
CLL
What translocation is associated with follicular lymphoma?
BCL2 (14;18)
What is the function of BCL2?
Antagonizes apoptosis and promotes cell survival (follicular lymphoma)
What are the characteristics of follicular lymphoma?
Painless, generalized lymphadenopathy in middle aged adults
Spleen shows expanded white pulp with prominent nodules
Transformation can occur
What are the characteristics of diffuse large B-cell lymphoma?
Diffuse pattern obliterates the nodal architecture
> 60
Rapidly enlarging mass
Remission with chemo 60-80%
What gene translocation is associated with Burkitt lymphoma?
C-MYC
What is the characteristic pattern associated with Burkitt lymphoma?
Microscopic starry sky due to the phagocytosis of apoptosis bodies
What are the three forms of Burkitt lymphoma?
African/endemic (EBV)
Sporadic/nonendemic
Patients with HIV
What cells are involved in plasma cell neoplasms?
Terminally differentiated B-cells
What is the term for he monoclonal Ig in the blood of patients with plasma cell neoplasm?
M component
What are Bence Jones proteins?
Free light chains (excreted in urine in plasma cell neoplasms)
What are two common forms of plasma cell neoplasms and their characteristics?
Multiple myeloma- plasma cell tumours in axial skeleton, renal failure and infection
Waldenstrom macroglobinemia- high levels of IgM lead to increased blood viscosity
Monoclonal gammopathy of undetermined significance
What mutation is associated with lymphoplasmacytic lymphoma?
MYD88
What are the characteristics of lymphoplasmacytic lymphoma?
B-cell neoplasm
Older adults
Cryoglobulinemia
No bone lesions or kidney failure
What translocation is associated with mantle cell lymphoma?
11;14
What are the characteristics of mantle cell lymphoma?
Mantle zone B-cells surround germinal centres
Male predominance
50-60
Extranodal disease is common
What are the characteristics of marginal zone lymphomas?
Heterogenous B-cell tumours
Arise in nodes and spleen
MALTomas
Occur at sites of chronic immune or inflammatory reactions
When may marginal zone lymphomas regress?
If the inflammatory stimulus is removed
What are the characteristics of hairy cell leukemias?
Plasma cell tumour
Hair like projections on cells
Splenomegaly (red pulp infiltrated)
Males more affected
Often give dry tap (cells trapped in ECM)
What is the point mutation associated with hairy cell leukemia?
BRAF
What are the types of peripheral T and NK cell neoplasms?
- Unspecified
- Anaplastic large cell lymphoma
- Adult T-cell leukemia/lymphoma
- Mycosis fungoides and Sezary syndrome
- Large granular lymphocytic leukemia
- Extranodal NK or T-cell lymphoma
Chromosomal rearrangements in anaplastic large cell lymphoma involve what?
ALK
What age does anaplastic large cell lymphoma occur in?
Children and young adults
What do the nuclei of cells involved with anaplastic large cell lymphoma look like?
Large, primitive, horseshoe shaped
What virus is associated with adult T-cell leukemia/lymphoma?
HTLV-1
What is the morphology of CD4 cells in adult T-cell leukemia/lymphoma?
Multilobar clover leaf nuclei
What is the pathology of mycosis fungoides and Sezary syndrome?
CD4 cells home to skin
What is the difference between mycosis fungoides and Sezary syndrome?
MF- involves epidermis and upper dermis, can spread outside of skin
SS- exfoliating erythroderma, localized to skin
What are the characteristics of large granular lymphocytic leukemia?
Large lymphocytes with blue cytoplasm and azurophilic granules
Neutropenia and anemia
Increased incidence of rheumatologic disorders
What syndrome is associated with large granular lymphocytic leukemia and what are its characteristics?
Felty syndrome
RA, splenomegaly and neutropenia
What virus is associated with extranodal NK or T-cell lymphoma?
EBV
What are the characteristics of extranodal NK or T-cell lymphoma?
Invaded small vessels and causes necrosis
Destructive nasopharyngeal masses
How is Hodgkin lymphoma differentiated from NHL?
Localized
Orderly spread/contiguous
Rare mesenteric node and Waldeyr ring involvement
Rare extranodal presentation
Can’t be diagnosed with flow cytometry
Reed-Sternburg cells are necessary for diagnosis
What are Reed-Sternburg cells?
B-cells from germinal centres that release factors inducing the accumulation of active lymphs, macs and grans
What are the subtypes of Hodgkin lymphoma?
- Nodular sclerosing
- Mixed cellularity
- Lymph rich
- Lymph depletion
- Lymph predominance
What are the most and least common types of Hodgkin lymphoma?
Most- nodular sclerosing
Least- lymph depletion
What are the categories of myeloid neoplasms?
- Acute myeloid leukemia (AML)
- Myelodyplastic syndrome (MDS)
- Myeloproliferative disorders (MPD)
What is the pathology of myeloid disorders?
Feedback mechanisms that modulate cell production in the marrow are deranged
Cells escape normal homeostatic controls
What are the characteristics of AML?
Accumulation of immature myeloid blasts
> 60
Anemia, neutropenia, thrombocytopenia (pan but mostly WBC)
Can acquire DIC
What are the characteristics of MDS?
Maturation defects with ineffective hematopoiesis
Dysplasic differentiation in all three lineages
Pseudo-Pelger-Huet bodies
What can MDS transform to?
AML
What mutation is associated with MPD?
Constitutively active tyr kinases
What are the characteristics of MPD?
Increased marrow proliferation
Extramedullary hematopoiesis
What are the different MPD?
- Chronic myelogenous leukemia (CML)
- Polycythemia Vera (PV)
- Essential thrombocytosis (ET)
- Primary myelofibrosis (PMF)
What mutation is associated with CML?
BCR-ABL fusion on Philadelphia chromosome (t(9:22))
What are the characteristics of CML?
Leukocytosis
Fatigue, weakness, weight loss, anorexia
50-60
What mutation is associated with PV?
JAK2
What are the characteristics of PV?
Erythrocytosis
Increased erythroblast, granulocyte and platelet production
Platelet dysfunction and abnormal blood flow
Organmegaly (extramedullary hematopoiesis)
What is the treatment for PV?
Phlebotomy
What are the characteristics of ET?
Increased proliferation and production of megakaryocytes
Thrombosis
Giant platelets
Erythromelalgia
What is erythromelalgia?
Throbbing/burning of hands and feet due to platelet aggregates in arterioles
What mutation is associated with PMF?
JAK2
What are the characteristics of PMF?
Obliterative marrow fibrosis
Leukoerythroblastosis
Extramedullary hematopoiesis and organmegally
Anemia, splenomegaly, bleeding
What is Langerhans cell histiocytosis?
Monoclonal, neoplastic proliferation of immature dendritic cells
What is characteristic of Langerhans cell histiocytosis?
Birbeck granules in cytoplasm
Tennis racket appearance of cells- pentalaminar tubules with dilated ends
What are the types of Langerhans cell histiocytosis?
- Multifocal-multisystem/Letterer Siwe disease
- Unifocal and multifocal-unisystem/eosinophilic granuloma
- Pulmonary
What are the functions of the spleen?
- Phagocytosis of blood cells and particulate matter
- Ab production
- Hematopoiesis
- Sequestration of formed blood elements
What is considered splenomegaly?
> 150g
What does splenectomy increase?
Susceptibility to sepsis by encapsulated bacteria
What can cause nonspecific acute splenitis?
Any blood-borne infection
What is the morphology of the spleen in nonspecific acute splenitis?
Red and soft (susceptible to rupture)
What can cause congestive splenomegaly?
Right sided heart failure
Impairment of portal venous drainage
Why does congestive splenomegaly protect the spleen from rupture?
Capsule becomes thickened and fibrous, harder to rupture
When are splenic infarcts seen?
Any condition causing splenomegaly
Emboli infarcts
Severe atherosclerosis
What types of neoplasms are common in the spleen?
Myeloid and lymphoid tumours
What congenital abnormality of the spleen is relatively common?
Accessory spleens
What is splenic rupture normally due to?
Blunt trauma
What is the function of the thymus?
T-cell maturation
T-cell production (until adulthood)
What developmental disorders of the thymus as common?
Hypoplasia/aplasia (DiGeorge)
Cysts
Hyperplasia- reactive B-cell follicles
What disorder is thymic hyperplasia seen?
Myasthenia gravis
Where do most thyomas occur?
Anterior mediastinum
What are the characteristics of thyomas?
Thymic epithelial cells
Lobulated, form, grey-white masses
Cystic necrosis and calcification
Most are encapsulated