Haematology: Pathology - Haematopoietic system Flashcards
Two broad causes of neutropenia
- Decreased or ineffective haematopoiesis
- Increased neutrophil removal/destruction
Four causes of decreased or ineffective haematopoiesis which may lead to agranulocytosis
- HSC suppression (e.g. in aplastic anaemia or infiltrative marrow disorders)
- Suppression of granulocytic precursors (commonly due to drugs e.g. chlorpromazine)
- Ineffective haematopoiesis (e.g. in megaloblastic anaemia or MDS)
- Congenital conditions
Three causes of increase neutrophil removal/destruction which may lead to agranulocytosis
- Immunologically mediated (e.g. SLE or due to drugs e.g. thiouracil or sulfonamides)
- Splenomegaly (increased neutrophil sequestration)
- Increased peripheral utilisation (due to infection)
How is agranulocytosis treated?
Broad-spectrum Abx if evidence of infection
May use G-CSF
At what neutrophil level is serious infection more likely?
<500 neutrophils per mm^3
What fungal organisms may cause deep infection in the neutropenic patient?
Candida
Aspergillus
What causes of neutropenia will result in bone marrow hyper- vs hypo-cellularity?
Hypercellularity: ineffective haematopoiesis, increased peripheral utilisation
Hypocellularity: suppression of granulocytic precursors
Four broad causes of leukocytosis
- Increased bone marrow production
- Increased release from marrow stores
- Decreased margination
- Decreased extravasation into tissues
Three causes of increased bone marrow production of leukocytes
- Chronic infection/inflammation
- Paraneoplastic (e.g. Hodgkin’s lymphoma)
- Myeloproliferative disorders (e.g. CML)*
*GF-independent (others are GF-dependent)
Three causes of increased release of leukocytes from marrow stores
- Endotoxaemia
- Infection
- Hypoxia
Two causes of decreased margination of leukocytes
- Exercise
- Catecholamines
Cause of decreased leukocyte extravasation into tissues
Glucocorticoids
Outline the typical causes of the various subtypes of leukocytosis (neutrophilia, eosinophilia, basophilia, monocytosis and lymphocytosis)
Neutrophilia: bacterial infection, sterile inflammation (e.g. in MI, burns)
Eosinophilia: allergic disorders, parasitic infection, drug reactions, some malignancies (e.g. lymphomas), collagen vascular disorders and some vasculitides
Basophilia: rare, often indicative of myeloproliferative disease (e.g. CML)
Monocytosis: chronic infection (e.g. TB), bacterial endocarditis, rickettsiosis, malaria, SLE, IBD
Lymphocytosis: accompanies monocytosis in chronic infection/inflammation, viral infection
What morphological changes are seen in neutrophils in severe inflammatory disorders (e.g. Kawasaki disease)?
Toxic granulations
Dohle bodies (dilated ER)
Cytoplasmic vacuoles
Microscopic changes seen in acute lymphadenitis
Large reactive germinal centres
Macrophages
May be central necrosis
Hyperplasia of endothelial cell lining
Three subtypes of microscopic patterns seen in chronic lymphangitis. What causes each?
- Follicular hyperplasia: humoral responses (e.g. RA, toxoplasmosis, early HIV)
- Paracortical hyperplasia: T-cell mediated responses (e.g. acute viral infection such as infectious mononucleosis)
- Sinus histiocytosis: in lymph nodes draining cancers
Microscopic pattern seen in follicular hyperplasia
Large oblong germinal centres (secondary follicles) surrounded by mantle zone of naive B cells
Germinal centres divided into dark zone (with centroblasts) and light zone (with centrocytes)
Interspersed antigen-presenting dendritic cells and “tingible-body” macrophages
Microscopic pattern seen in sinus histiocytosis (reticular hyperplasia)
Hyperplasia and hypertrophy of cells lining lymphatic sinusoids
Increased macrophages
Microscopic pattern seen in paracortical hyperplasia
Expanded T-cell zones, may efface B-cell follicles
Immunoblasts may be so numerous that special studies are needed to exclude lymphoid neoplasm
Hypertrophy of sinusoidal and vascular endothelial cells
What is the most common types of chromosomal abnormality seen in white cell neoplasms?
Translocation
What are the three categories of white cell neoplasms?
Myeloid
Lymphoid
Histiocytoses
Six aetiological factors for white cell neoplasms
- Chromosomal translocations and other acquired mutations
- Inherited genetic factors
- Viruses
- Chronic immune stimulation
- Iatrogenic factors
- Smoking
Three examples of a chromosomal translocation in the pathogenesis of white cell neoplasms
- Roles in growth and development: e.g. translocations involving MALT1 or BCL10 cause MALTomas (B-cell lymphomas in extranodal sites)
- Oncoproteins created which block normal maturation: e.g. mutations up-regulating BCL6 (which under normal conditions is needed for the formation of germinal centre B cells but also blocks their maturation)
- Proto-oncogenes activated during Ag receptor gene rearrangement and diversification: in lymphoid cells most commonly occurs in B cells during attempted Ab diversification (e.g. c-MYC)
Four examples of genetic diseases conferring increased risk of leukaemia
Fanconi anaemia
Ataxia telangiectasia
Trisomy 21
Type I neurofibromatosis
Three examples of viruses contributing to the pathogenesis of white cell neoplasms (and the specific neoplasms they are linked to)
- Human T-cell leukaemia virus 1 (HTLV-1): adult T-cell lymphoma/leukaemia
- Epstein-Barr virus (EBV): subset of Burkitt lymphoma, Hodgkin lymphoma, many B-cell lymphomas, rare NK-cell lymphomas
- Kaposi sarcoma herpesvirus (KSHV; aka human herpesvirus-8, HHV-8): Kaposi sarcoma, rare B-cell lymphoma that presents as malignant (often pleural) effusion
Three examples of chronic immune stimulation leading to increased risk of certain white cell neoplasms
- H. pylori infection: increased risk gastric B-cell lymphomas
- Gluten-sensitive enteropathy: increased risk intestinal T-cell lymphomas
- HIV: initially increased risk of germinal centre B-cell lymphomas, late-stage (in setting of AIDS) increased risk of B-cell lymphomas particularly those associated with EBV and KSHV
Smoking increases risk of developing which white cell neoplasm?
AML
Five categories of lymphoid neoplasms according to cell of origin (and give an example of each)
- Precursor B-cell neoplasms (immature B-cells): e.g. B-ALL
- Peripheral B-cells neoplasms (mature B-cells): e.g. DLBCL, follicular lymphoma
- Precursor T-cell neoplasms (immature T cells): e.g. T-ALL
- Peripheral T-cell and NK-cell neoplasms (mature T cells and NK cells): e.g. adult T-cell leukaemia/lymphoma
- Hodgkin lymphoma (Reed-Sternberg cells and variants)
What is the most common form of indolent NHL?
Follicular lymphoma
What kind of neoplasm is multiple myeloma?
Plasma cell neoplasm
Which growth factor is important in the proliferation and survival of myeloma cells?
IL-6
Describe the histological findings in multiple myeloma. What feature is seen on a peripheral smear? What proteins are excreted in the urine and what is the pathological significance of this?
Plasmacytomas (destructive plasma cell tumours) involving axial skeleton
May see relatively normal-appearing plasmablasts, or flame (with red cytoplasm) or Mott cells, bizarre multinucleated cells with cytoplasmic droplets containing Ig (Russell bodies; if nuclear they are called Dutcher bodies)
Roleaux formation on peripheral smear (high M proteins causes red cells to stick to one another)
Bence Jones protein (light chains) excreted in urine and contributes to myeloma kidney (renal disease)
Most common site of pathological fracture in multiple myeloma
Vertebral column
Clinical features of multiple myeloma
CRAB:
HyperCalcaemia
Renal disease
Anaemia
Bony involvement (lesions, pathological fractures)
How is risk of transition to multiple myeloma from MGUS measured/monitored?
Serum M proteins
Urine Bence Jones protein
Compare and contrast features of Hodgkin vs non-Hodgkin lymphoma in terms of typical distribution and progression, extra-nodal involvements, and specific histological features
Hodgkin lymphoma:
Distribution: localised to single axial group of lymph nodes (e.g. cervical, mediastinal, para-aortic), mesenteric nodes and Waldeyer ring rarely involved
Progression: orderly spread by contiguity
Extra-nodal involvement: rare
Histological features: Reed-Sternberg cells
Non-Hodgkin lymphoma:
Distribution: involvement of multiple peripheral nodes, mesenteric nodes and Waldeyer ring commonly involved
Progression: noncontiguous spread
Extra-nodal involvement: common
Histological features: dependent on subtype
What are Reed-Sternberg cells?
Large cells (>45um) with multiple nuclei or single nucleus with multiple lobes, each with a large inclusion-like nucleolus about the size of a small lymphocyte (5-7um)
What is the most common form of Hodgkin lymphoma?
Nodular sclerosis