Pathology of lymphoid system Flashcards
List 3 primary lymphoid organs
Thymus
bone marroe
bursa of Fabricius
List 3 secondary lymphoid organs
spleen
lymph nodes
lymph nodules (e.g. MALT)
When you see one enlarged lymph node what should we do
Look at what area that drains as this will help narrow don where the problem is
when is it indicated to investigate a lymph node
lymph node enlargement
suspect of an underlying infectious disease (e.g. Leishmania, FIP, fungi)
stage malignant neoplastic diseases
provide material for molecular testing
Why when you are sampling a lymph node does the needle need to be directed tangentially
to avoid more central points
very large nodes may have areas of haemorrhage or necrosis
List the key points of sample collection from lymph nodes
spread gently
non suction technique to minimise blood contamination
ideally take sample before giving steroids
avoid aspiration of centre
Describe how a normal lymph node looks
small lymphocytes –> 90%
medium and large large lymphocytes –> <5-10%
plasma cells, macrophages mast cells, neutrophils are rare to see
What are Lymphoglandular bodies
fragments of cytoplasm of disrupted lymphocytes
list the 4 causes of lymphadenopathy
reactive hyperplasia
lymphoma
lymphadenitis
metastatic neoplasia
What happens in primary lymphoid organs
Are where B and T lymphocytes proliferate, differentiate and mature
What are the secondary lymphoid organs
resposinsible for the immune responses to antigen
Describe what is seen on cytology with reactive hyperplasia in lymph nodes
cytologically can be indistinguishable from a normal lymph node
small lymphocytes are predominant
can see an increase in number of medium and large lymphocytes
What is lymphadenitis
accumulation of inflammatory cells
can be classified based on what inflammatory cell is present
What causes can neutrophilic lymphadenitis suggest
bacterial
immune mediated
neoplastic
what can cause eosinophilic lymphadenitis
hypersensitivity reaction
parasites
idiopathic
paraneoplastic (e.g. mast cell tumour, lymphoma)
List the causes of macrophagic/granulomatous lymphadenitis
chronic inflammatory conditions (e.e.g fungal infection, mycobacteriosis, leishmaniasis, FIP)
Describe what is seen on cytology with lymphoma
homogenous appearance
most commonly increased percentage (>50%) of large immature lymphocytes
tingible bodies macrophages
Describe what can be seen on cytology with metastatic neoplasia
presence of cells not normally found in lymph nodes ( e.g. carcinoma, sarcoma)
increased numbers of cells normally present with atypical morphology (e.g. mast cells)
Decribe the function of red pulp the spleen
is a reservoir of blood
filter for senescent or damaged erythrocytes
iron metabolism
Describe the function of the white pulp of spleen
immunity against blood borne antigens
what is the function of the capsule of the spleen
can contract causing the release of blood in circulation (e.g. in response to acute blood loss)
when is it indicated to investigate the spleen
enlargement
nodular or focal lesions
abnormal ultyrasound appearance
evaluation of haematopoiesis
tumour staging
what are the key points when sampling the spleen
non-suction technique
spread gently
avoid contamination with lubricant gel
ideally take sample before giving steroids
Describe the noraml cytological appearance of the spleen
small lymphocytes 90%
medium and large lymphocytes 5-10%
plasma cells, macrophages, mast cells rare
neutrophils present in blood proportions
List the 5 causes of splenomegaly
reactive hyperplasia
lymphoma
splenitis
metastatic neoplasia
extramedullary haematopoiesis
Describe the thyroid
is a primary lymphoid organ
located in the cranial mediastinum
List 2 pathologies that affect the thymus
thymoma
lymphoma
why is it important to distinguish thymoma from lymphoma
they come from different origins
have different treatments
where do thymoma originate and how are they treated
epithelial cells
surgical treatment
where do lymphoma originate and how is it treated
lymphocytes
chemotherapy- as systemic disease
