Structure and function of lymph node and spleen Flashcards
name primary/central lymphoid structures
bone marrow and thymus
name secondary/peripheral lymphoid structures
lymph nodes
spleen
tonsils/adenoids
Peyer’s patch in intestine
lymphadenopathy causes
local inflammation
- infection
- others e.g. vaccination, dermatopathic
systemic inflammatory processes
- infection e.g. viral infections
- autoimmune/CT disorders
malignancy
- haematological - lymphoma/leukaemia
- metastatic
others
- e.g. sarcoidosis, Kikuchi’s lymphadenitis, Castlemans Disease; IgG4 related disease
how can internal lymph nodes be viewed
radiologically
give 2 examples of internal lymph node groups
mediastinal
para-aortic
what is the sentinel lymph node
the first lymph node to which cancer cells are most likely to spread
there may be more than one sentinel node
what is the sentinel lymph node identified by
dye or radioactive isotopes
afferent lymphatics penetrate the capsule (connective tissue surrounding the node) and drain into ________ ______
subcapsular sinus
flow of lymphatics (6 points)
- Node is surrounded by connective tissue CAPSULE
- AFFERENT LYMPHATICS penetrate the capsule and drain into SUBCAPSULAR SINUS
- Lymph from subcapsular sinus percolates THROUGH THE NODE
- Lymph enters MEDULLARY CORDS and SINUSES
- Sinuses merge at HILUM and form EFFERENT LYMPHATICS
- Lymph rejoins extranodal lymphatic circulation
lymphangitis
inflammation of your lymphatic vessels
what are the 3 important regions of lymph node
cortex
paracortex
medulla
lymph node cortex
Nodules of B lymphocytes arranged in follicles (primary / secondary)
lymph node paracortex
- Mainly T lymphocytes
- Forms the interfollicular tissue which surrounds follicles and extends out and merges with medulla
lymph node medulla
Cords and sinuses draining into hilum
what cell populations are in lymph nodes
- B cells
- T cells
- Mononuclear phagocytes (macrophages), antigen presenting cells, and dendritic cells
- endothelial cells
CD20 is a __-cell marker
B
CD3 is a __-cell marker
T
two types of follicles in a lymph node
primary
secondary
primary follicles in lymph node
Small quiescent lymphocytes
Unstimulated
No germinal centre
secondary follicles in lymph node
Activated follicles
Reactive
Germinal centre
what are follicular dendritic cells
specialised antigen presenting cells in the follicle.
they are mesenchymal and form meshworks through the germinal centre
in a follicle, antigen-antibody complexes are captured by _________ _________ ______(FDCs)
follicular dendritic cells
in lymph node follicles, do B cells divide/clonal expansion in the light or dark zone
dark
centroblast
proliferating B cell in dark zone of follicle in lymph node
what will centroblast proliferate into
centrocyte
positively selected B cells go one of 2 ways:
Reenter dark zone and keep proliferating (and expressing cMyc to regulate GC formation)
Differentiate into plasma cells
Differentiate into memory B cells
what is a centrocyte
B cell in light zone
Will become either memory B cell or plasma cell
what is in the lymph node medulla
Blood vessels
Sinuses
Medullary cords
- Plasma cells, B cells, macrophages
Medullary sinuses
- Histiocytes, reticular cells
- Lymph then drains into efferent vessels
Granulomatous lymphadenitis
there are aggregates of histiocytes.
there is a wide differential diagnosis, e.g. sarcoidosis
sarcoidosis
A granulomatous condition.
Systemic disease, requires clinical correlation
Sarcoid like reactions can also appear similar
May mask malignancy in a lymph node
granulomatous inflammation - when caseous necrosis is present what are we thinking?
Infectious cause (Mycobacterial) until proven otherwise (TB bascially)
what does generalised lymphadenopathy suggest
a systemic inflammatory / immunological process or widespread malignancy
what are lymphomas
Malignant tumours derived from cells of the immune system
what is the most common form of lymphoma
non hodgkins lymphoma
what is the most common form of non hodgkins lymphoma
B cell lymphomas
types of non hodgkins lymphoma
B cell
T cell
hodgkin’s lymphoma prognosis
usually very good
types of hodgkins lymphoma
classical
nodular lymphocyte predominant
which is more common - non-hodgkins lymphoma or hodgkins lymphoma
non hodgkins
where is the spleen located
Located high in the left upper quadrant of the abdomen
spleen - two key aspects: __________ surface and ________ surface
diaphragmatic
visceral
the spleen is a very vascular organ, true or false
true
spleen vascular supply and drainage
supplied by splenic artery (branch of coeliac trunk) and drained by splenic vein (with superior mesenteric vein forms portal vein)
splenic rupture (surgical emergency!) causes
trauma
a diseased spleen is more prone to rupture
