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*Medicine: Cellular Pathology > Lymph node pathology > Flashcards

Lymph node pathology Flashcards

1
Q

What are the two main components of the lymphatic system?

A
  • a conducting system (lymph vessels) which transport lymph from the interstitium to the circulation
  • lymphoid tissue (lymph nodes, MALT, spleen etc)
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2
Q

Lymph is the name given to interstitial fluid when it enters the lymphatic system. What is the role of lymph within the immune system?

A
  • transports antigen-presenting cells (APCs) to lymph nodes + MALT (mucosa-associated lymphoid tissue)
  • APCs present antigen to naïve lymphocytes in the lymph nodes + MALT thus stimulating an adaptive immune response
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3
Q

What is lymphadenopathy?

A

enlarged lymph nodes

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4
Q

What is a useful investigation for lymphadenopathy?

A

FNA

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5
Q

What are the causes of lymphadenopathy?

A
  • reactive to infection - acute (influenza, infectious mononucleosis) or chronic (TB, HIV)
  • malignant tumour - primary (lymphoma) or secondary (metastatic tumour such as carcinoma or melanoma which have spread from elsewhere to involve lymph nodes)
  • multisystem disorders - sarcoidosis, SLE, rheumatoid arthritis
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6
Q

Lymphomas are a large group of haematological malignancies. Why do lymphomas occur and thus how do they present?

A
  • lymphomas occur due to mutations in a lymphocyte that has left the bone marrow and taken up residence in a lymph node
  • lymphomas therefore tend to present with solid mass lesions, particularly enlarged lymph nodes (rather than abnormal blood counts)
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7
Q

Over 90% of lymphomas are derived from B lymphocytes. Why is this?

A
  • B cells are able to produce specific antibodies to an almost infinite range of antigens
  • B cells do this by a process of somatic hypermutation
  • in response to antigen stimulation they re-arrange their immunoglobulin genes to produce an infinite range of possible antibodies
  • during this re-arrangement phase they are at risk of acquiring mutations in growth-controlling genes which can give rise to malignant behaviour ie. development of lymphoma
  • T lymphocytes do not undergo somatic hypermutation and so there is lower risk of malignant transformation in T lymphocytes
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8
Q

Lymphomas are divided into two broad groups. What are they?

A
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9
Q

Hodgkin lymphoma represents a special group of lymphomas which account for 1 in 3 lymphomas. What is the distribution of incidence?

A
  • bimodal distribution of incidence
  • peak in young adulthood (15-35yo)
  • second peak in 55+ age group
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10
Q

The aetiology of Hodgkin lymphoma is poorly understood. What are the established risk factors?

A
  • history of Epstein Barr Virus (EBV) infection
  • immunosuppression eg. HIV infection
  • family history
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11
Q

How does Hodgkin lymphoma present clinically?

A
  • lymphadenopathy (typically supraclavicular or cervical)
  • there may be ‘B symptoms’ (systemic) eg. fever, weight loss, night sweats
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12
Q

Diagnosis of Hodgkin lymphoma requires exicison of a node for histological examination. What is the defining pathological feature of Hodgkin lymphoma?

A
  • presence of Reed-Sternberg cells
  • the tumour cells seen in Hodgkin lymphoma
  • thought to be derived from B-lymphocytes
  • typically large cells w/ 2 nuclei (binucleate)
  • prominent pink nucleoli imparting an ‘owls eye’ appearance
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13
Q

Non-Hodgkin lymphomas (NHL) account for about 2/3 lymphomas. Where do most arise?

A
  • most arise from B lymphocytes (~90%)
  • minority arise from T lymphocytes
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14
Q

The classification of NHLs is complex; you are not expected to know all the different types of NHL.

How can the two types of NHL be divided?

A
  • B-cell NHLs can be divided into 2 groups depending on their clinical behaviour:
    • indolent
    • aggressive
  • _T-_cell NHLs usually show aggressive clinical behaviour
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15
Q

Describe characteristics of indolent non-Hodgkin lymphomas

A
  • eg. marginal zone lymphoma
  • tend to present w/ widely disseminated disease at diagnosis involving several nodal + extranodal sites
  • typically follow a slowly progressive course
  • can be controlled w/ treatment but cure rarely achievable
  • survival is typically in region of 8-10 years
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16
Q

Describe characteristics of aggressive non-Hodgkin lymphomas and what the most common type of Non-Hodgkin lymphoma is

A
  • eg. diffuse large B cell lymphoma (most common NHL)
  • tend to present w/ short Hx of rapidly growing mass at a localised nodal or extranodal site
  • typically follow a rapidly progressive course
  • usually rapidly fatal if untreated but therapy may lead to complete cure
17
Q

Describe the lymphoma staging system

A

Modified Ann-Arbor system:

  • stage I - involvement of 1 lymph node region
  • stage II - involvement of 2+ lymph node regions on same side of diaphragm
  • stage III - involvement of lymph node regions on both sides of diaphragm
  • stage IV - involvement of extranodal sites eg. liver, bone marrow, lungs

A - no B-symptoms
B - B-symptoms present (night sweats, fever, weight loss)

18
Q

What is sarcoidosis and what causes it?

A
  • multisystem disease of unknown aetiology
  • characterised by presence of non-caseating granulomas in tissues + organs
  • an inflammatory response to some unidentified environmental agent in a susceptible host
  • infective cause has long been sought, in particular a mycobaterium due to the granulomatous response
  • however, no study has equivocally proven an infective aetiology
  • inhaled antigens such as pine pollen + peanut dust have been incriminated
  • existence of familial clusters suggests genetic factors may be involved
19
Q

Remember that a granuloma is an aggregate of activated macrophages. How do the granulomas in sarcoidosis differ from TB?

A

granulomas in sarcoidosis do not show caseous necrosis

20
Q

Sarcoidosis may involve virtually any organ but some are involved more than others.

What is the involvement with lymph nodes?

A
  • virtually all cases of sarcoidosis involve lymph nodes
  • any lymph node may be involved
  • most common are hilar and mediastinal nodes
  • enlargement of these nodes usually picked up on CXR
21
Q

What is the involvement of sarcoidosis within the lungs?

A
  • lungs frequently involved by sarcoidosis
  • healing of granulomas may lead to varying degrees of lung fibrosis
  • severe sarcoidal lung disease -> cor pulmonale (RHF due to lung disease) + resp failure
22
Q

What is the involvement of sarcoidosis with the skin?

A
  • skin involvement typically presents as lupus pernio
  • an asymptomatic maculopapular rash on face and trunk
  • erythema nodosum may be associated w/ sarcoidosis
23
Q

What is the involvement of sarcoidosis and the eyes?

A
  • typically causes uveitis (=inflammation of uveal tract)
  • anterior uveitis -> red painful eye w/ photophobia, often self-limiting
  • posterior uveitis -> floaters due to inflammatory cells appearing in vitreous w/ some blurring of vision, more chronic form of the disease
24
Q

What is the involvement of sarcoidosis and the lacrimal/salivary glands?

A
  • dry eyes
  • dry mouth
25
Q

What is the involvement of sarcoidosis with the nervous system?

A
  • sarcoidosis can affect the central + peripheral nervous systems
  • a CN VII (facial) palsy is common
  • hypothalamic involvement also common -> diabetes inspidus due to destruction of ADH-producing neurones
26
Q

Sarcoidosis may be divided into an acute and chronic form.

Most patients get acute sarcoidosis - describe this?

A
  • associated w/ manifestations that include bilateral hilar lymphadenopathy, anterior uveitis + a CN VII palsy
  • has a good prognosis
  • typically spontaneous resolution within 1-2yr of diagnosis
  • no long-lasting consequences
27
Q

About 5% of patients will develop acute sarcoidosis - describe this?

A
  • tends to persist and lead to permanent organ damage
  • associated w/ lupus pernio, pulmonary fibrosis + posterior uveitis
  • these pts at higher risk of developing permanent organ damage
  • end-stage lung fibrosis is the most serious consequence for pts w/ severe chronic sarcoidosis
  • leading to resp failure + cor pulmonale
28
Q

Simple haematological blood tests can be helpful in supporting a suspected diagnosis of sarcoidosis, though they are not specific. What do they show?

A
  • ESR often raised
  • hypercalcaemia is present in ~10% cases (due to conversion of vitamin D -> active 1,25-dihydroxycalciferol within granulomas)
  • serum levels of ACE are raised in most pts w/ active sarcoidosis (granulomas produce ACE + so serum ACE levels may be used to help establish diagnosis + predict relapse or remission)
29
Q

In typical cases of sarcoidosis, the clinical picture + other simple investigations can be sufficient to make an accurate diagnosis of sarcoidosis. What can be done in less clear-cut cases?

A

Biopsy of an affected organ may be necessary to demonstrate the presence of non-caseating granulomas and exclude other differential diagnoses

30
Q

Review the haematopoeisis pathway and in particular where each cell type normally resides

A
31
Q

How does acute leukaemia result from the haematopoetic pathway?

A
32
Q

What happens if differentiation does occur in regards to haematopoeisis and haemotological malignancy?

A
33
Q

How are lymphomas different to leukaemias?

A
  • mutations giving rise to malignant tumour occur in lymphocytes that have left** the bone marrow and taken up residence in **lymph nodes or other organs
  • lymphomas therefore tend to present with solid mass lesions, particularly enlargement of lymph nodes, rather than an abnormal blood count
34
Q

What is the most common type of plasma cell malignancy?

A
  • plasma cells are terminally differentiated B cells that have encountered antigens + fully matured into immunoglobulin-secreting cells
  • as part of their normal fxn, many plasma cells home back to the bone marrow where they secrete their antibodies
  • most common type of plasma cell malignancy = multiple myeloma
  • myeloma is characterised by bony lesions due to destructive growth in the bone marrow
  • this reflects the fact that normal plasma cells home back to the bone marrow
  • in addition, patients w/ myeloma develop problems related to the large quantities of immunoglobulin the plasma cells produce

*Medicine: Cellular Pathology (16 decks)

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