Joseph Hall Flashcards
What does the indented part of the monocytes nucleus signify
Golgi apparatus
How long do platelets take to make?
7-10 days
NB: Platelets bind and degrade thrombopoietin, a mechanism that regulates platelet production (liver and kidneys)
What is unique about the cytoplasm of platelets
Has cytoplasmic channels, called the invaginated membrane system, an arrangement that enables the absorption of clotting factors.
Where does hemopoiesis occur
Red bone marrow, in two microenvironmental domains, called niches:
1. The vascular niche.
2, The endosteal niche.
What are the primary lymphoid organs
- BM
2. Thymus
What are the secondary lymphoid organs
- LNDs
- Spleen
- Tonsils
- aggregates of lymphocytes and antigen-presenting cells in the lung (bronchial-associated lymphoid tissue, BALT) and the mucosa of the digestive tract (gut-associated lymphoid tissue, GALT), including Peyer’s patches.
Path of B and T cells
After leaving the two primary organs, mature B and T cells circulate in the blood until they reach one of the various secondary lymphoid organs (lymph nodes, spleen, and tonsils).
What are accessory cells?
Accessory cells include two monocyte-derived cell types:
- Macrophages
- Dendritic cells. i.e. Langerhans cell found in the epidermis of the skin.
- Follicular dendritic cell, a third type, present in lymphatic nodules of the lymph nodes. Follicular dendritic cells differ from ordinary dendritic cells in that they do not derive from a bone marrow precursor.
Specific features ofdiffuse lymphatic tissue or mucosa-associated lymphatic tissue (MALT) or lymphatic nodules
Guard the body against pathogenic substances and are the sites of initial immune response.
Accumulation of lymphatic cells that are NOT enclosed by a capsule.
Lymphocytes are found in the lamina propria (subepithelial tissue).
What are primary nodules
A nodule that contains primarily lymphocytes
What are secondaryy nodule
- Contains a germinal centre - in the central region of the nodule. Lightly stained due to the presence of large immature lymphocytes. Follicular Dendritic cells and mitotic figures are frequent.
- Mantle zone or corona: an outer ring of small lymphocytes that encircle the germinal center.
What are lymphatic tissues of the alimentary canal
Dispersed in a random manner, but in the alimentary canal are found in specific locations:
Tonsils- entrance of the oropharynx
Peyer’s patches: in the ileum
Appendix
Function of lymph nodes
- They filter the lymph, maintain and differentiate B cells, and house T cells.
- Detect and react to lymph-borne antigens.
- They are concentrated in certain regions such as the axilla, groin and mesenteries.
What are the lymphatic vessels
Afferent lymphatic vessel: bring lymph to the node.
Efferent lymphatic vessel: takes lymph away from the node.
What are the components of the lymph nodes
- Capsule: Dense connective tissue.
- Trabeculae: Dense connective tissue extending from the capsule inside the node.
- Reticular tissue: Composed of reticular cells and reticular fibers and covers the remaining of the organ
Cells of the reticular network?
- Reticular cells: secrete collagen type III
- Dendritic Cells
- Macrophages
- Follicular dendritic cells
General Architecture of the Lymph Node
- The lymph nodules are found in the outer part of the cortex, called the superficial (nodular) cortex.
- The portion between the medulla and the superficial cortex is called the Deep Cortex (paracortex). Is free of nodules. Most of the T cells are found in this region.
Features of the thymus
- Thymus is a bilobed organ.
- Site of T-cell differentiation.
- The thymus is fully formed and functional during birth.
- It persists until the time of puberty when T cell differentiation is reduced and most of the lymphatic tissue is replaced by adipose tissue.
Histology of the thymus
Connective tissue surrounds the thymus and subdivides the thymic parenchyma into thymic lobules.
Each lobule is composed of a cortical cap on top of an inner medullary tissue.
The thymic parenchyma contains developing T cells (thymocytes) in an extensive meshwork formed by epithelioreticular cells (large and pale nuclei).
On H&E stain, cortex is markedly basophilic because of the closely packed thymocytes.
Gross features of the spleen?
It filters blood and reacts immunologically to blood-borne antigens.
It is enclosed by a dense capsule of connective tissue, collagen, elastic and SM from which trabeculae extents into the parenchyma.
Spleen parenchyma is divided based on the color of fresh sections into the: White pulp (appears darker histologically) Red pulp (appears lighter histologically)
Arteries and veins found in the trabecula.
No cortex, medulla, and lymphatic vessels.
What is in the stroma of the spleen
Composed of reticular fibres, supporting:
White pulp (splenic nodules with B and T cells, antigen-presenting cells and plasma cells)
Red pulp (splenic sinusoids filled with blood and plates of lymphoid tissue — splenic cords)
Features of the white pulp
- Consist of lymphatic tissue, basophilic, mostly lymphocytes.
- Two types of lymphocytes, i.e., B cells and T cells located in two different areas of the spleen.
- B cells are located in the lymphoid follicles scattered throughout the organ
- T cells aggregate around a central artery and constitute the perarterial lymphatic sheath (PALS).
Resemble the lymphatic nodule
Features of the red pulp
Red appearance due to large number of red blood cells.
- Consists of splenic sinuses separated by splenic chords:
- Consist of a sponge-like meshwork of reticular cells, reticular fibers, macrophages and dendritic cells.
- Macrophages phagocytize pathogens, cell debris, and cells that are old, abnormal, or damaged, esp. red blood cells. Phagocytosis may be increased when the spleen is enlarged
Most common type of cancer in children
Leukemia - 80% ALL
- Brain is second most common
- Solid tumours are usually embryonal tumours rather than carcinoma
Risk factors for cancer in childhoo
- Genetic condition ( anomalies)
- Family history ( Li-Fraumeni syndrome )
- Environmental (ionizing radiation,
chemicals) - Infections ( EBV (B cell lymphoma) , HIV (karposi sarcoma), HBV (hepatocarcinoma))
- Chemotherapy (second cancer )
Signs of childhood cancer
Continued, unexplained weight loss
Headaches, often with early morning vomiting
Increased swelling or persistent pain in bones, joints, back, or legs
Lump or mass, esp. in the abdomen, neck, chest, pelvis, or armpits
Development of excessive bruising, bleeding, or rash
Constant/recurrent infections
A whitish color behind the pupil
Nausea which persists or vomiting with or w/o seizures
Constant tiredness or noticeable paleness
Eye or vision changes which occur suddenly and persists
Recurrent or persistent fevers of unknown origin
Frequency of the leukemias in children
- ALL - 84%
- AML - 15%
- CML - 1%
- JMML
- CLL —- extremely rare
Ddx of presenting symptoms of leukemia
- Easy brusing/ petichiae: aplastic anaemia, ITP
- Lymphadenopathy: Bacterial infx, mump, infectious mononucleosis
- Liver and spleen enlargeent: viral infection
Systemic symptoms f leukema
Lymphadenopathy
Hepatosplenomegaly
Orthopnea, cough
mediastinal mass
tracheal compression
Facial nerve palsy
Testicular enlargement
Skin lesions
Gingival hypertrophy(AML)
Which organs does leukemia hide
- Testicles
- Brain
- These are organs where there is blood tissue barrier so therapy is different and needs to be more direct
Tx of paed cancers
Chemo is mainstay radiotherapy only used for CNS positive diseases
Dx in Tx between boys and girls for ALL
Boys 3 years and 8 weeks
Girls 2 years and 10 weeks
Induction therapies for ALL
VCR
Steroids
Asparaginase
+/- daunorubicin
IT MTX
> 95% REMISSION RATE
Maintainence therapy for ALL
Daily 6MP & weekly MTX
Monthly VCR + Steroids
3 monthly IT MTX
Boys~ 2 yrs
Girls ~ 1 yr
Tx principles of AML
Needs Intensive treatment for 4-5 months.
Main cytostatica (Cytarabine, Etoposide, Daunorubicin, Mitoxantrone, Amsacrine)
Acute promyelocytic leukaemia-Chemotherapy plus
al-trans-retinoic acid (ATRA)
Subtypes of lymphoma
Hodgkin’s Disease (HD)
Nonhodgkin’s Lymphoma (NHL)
- Burkitt’s
- Lymphoblastic
- Anaplastic Large Cell