Difference between revisions of "Lymph nodes"

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The '''lymph node''', abbreviated '''LN''', is very important in pathology.  It is the site of mets and may be the site of a primary lesion, i.e. lymphoma.
'''Lymph nodes''', abbreviated '''LNs''', are very important in pathology.  They are the site of [[metastases]] and/or may be the site of a primary tumour, i.e. [[lymphoma]].


Haematopathology and lymphoma is dealt with in the ''[[haematopathology]]'' article.  This article covers the basics of LNs.
Haematopathology and lymphoma is dealt with in the ''[[haematopathology]]'' article.  This article covers the basics of lymph nodes.  Lymph node pathology is dealt with in the ''[[lymph node pathology]]'' article. [[Grossing]] is covered in ''[[lymph node grossing]]''.


==LN architecture==
=Clinical=
Lymph node architecture (superficial to deep):<ref>Wheater's FH. 4th Ed. PP.206-8.</ref>
===Normal (clinical)===
*Round.
*"Soft".
*Mobile.
 
===Pathologic (clinical) - associations===
*Rubbery = suggestive of lymphoma.
*Tender (hurts when ya touch it) = suggestive of infection.
*Fixed (immobile) = suggestive of [[cancer]], usually carcinoma.
*Hard = suggestive of cancer.
*"Large" - cancer or infection.
**What qualifies for "large" depends on the location in the body.
 
==Radiologic==
*Ellipical (as opposed to spherical) = may be cancer.
*"Large" = could be cancer or infection.
**What qualifies for "large" depends on the location in the body.
 
=Gross pathologic exam=
{{Main|Lymph node grossing}}
Normal:
*Firm (relative to adipose tissue).
*Glistening surface when cut.
 
Pathologic:
*White lesions, especially irregular = suggestive of carcinoma.
*White, glistening, with lobulated surface - "fish flesh" = suggestive of lymphoma.
**Subtle lobulation (~1 mm) on section suggestive of ''[[follicular lymphoma]]''.<ref>Bailey, D. 5 August 2010.</ref>
 
=Microscopic=
==Lymph node architecture==
Lymph node architecture (superficial to deep):<ref name=Ref_WFH4_206-8>{{Ref WFH4|206-8}}</ref>
*Capsule.
*Capsule.
*Subcapsular sinus.  
*Subcapsular sinus.  
**Place where metastatic cells often are found.
**Place where metastatic cells often are found.
**In a normal LN the vessels should be "open", i.e. have a discernible lumen.
*Cortex:
*Cortex:
**Follicles (superficial).
**Follicles (superficial).
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Notes:
Notes:
*Trabeculae - segment the LN radially, i.e. are spoke-like structures.
*[[Trabeculae]] - segment the LN radially, i.e. are spoke-like structures.


==LN follicles==
==Lymph node follicles==
Types of follicles:<ref>Wheater's FH. 4th Ed. P.208.</ref>
Types of follicles:<ref name=Ref_WFH4_208>{{Ref WFH4|208}}</ref>
#Primary follicle - no germinal center (pale area).
#Primary follicle - no germinal center (pale area).
#Secondary follicle - have a ''germinal center'' (pale area) and ''mantle zone'' (rim of darker staining lymphocytes).
#Secondary follicle - have a ''germinal center'' (pale area) and ''mantle zone'' (rim of darker staining lymphocytes).


===Germinal centre===
===Germinal centre===
Architecture:
Architecture:  
*Paler at capsular aspect.
*Paler at capsular aspect.  
*Darker at medullary aspect.
*Darker at medullary aspect.
Image:
*[http://www.pathpedia.com/education/eatlas/histology/lymph_node/normal-lymph-node-histology-%5B10-ln01-10h%5D.jpeg?Width=600&Height=450&Format=4 Secondary follicle (pathpedia.com)].<ref>URL: [http://www.pathpedia.com/education/eatlas/histology/lymph_node/images.aspx http://www.pathpedia.com/education/eatlas/histology/lymph_node/images.aspx]. Accessed on: 29 October 2012.</ref>


==Location and cell types==
==Location and cell types==
Germinal centers:<ref>Wheater's FH. 4th Ed. P.210.</ref>
Germinal centers:<ref name=Ref_WFH4_210>{{Ref WFH4|210}}</ref>
*Site of B lymphocyte proliferation; ''follicle center cells''.
*Site of B lymphocyte proliferation; ''follicle center cells''.  
**Centrocytes transforming to immunoblasts (superficial aspect - paler).
**Centroblasts - usually superficial aspect. (??? deeper ???)
***Darker, larger, nucleoli.
**Centrocytes (mid germinal center).
**Centrocytes (mid germinal center).
**Centroblasts (deeper aspect - darker).
***Cells with cleavage.
**Centrocytes (transforming to immunoblasts) - usually deeper aspect. (??? superficial ???)
***Cells with cleavage.
*''Tingible body macrophages'' - mid germinal center.
*''Tingible body macrophages'' - mid germinal center.
*''Follicular dendritic cells''.
*''Follicular dendritic cells''.


Paracortex:<ref>Wheater's FH. 4th Ed. P.211.</ref>
Paracortex:<ref name=Ref_WFH4_211>{{Ref WFH4|211}}</ref>
*Site of T lymphocytes.
*Site of T lymphocytes.
*''Interdigitating dendritic cell''.
*''Interdigitating dendritic cell''.
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Mantle zone:
Mantle zone:
*Memory B cells.
*Memory B cells.
*Usually asymmetrical; thicker, i.e. more mantle cells, at capsular aspect.<ref>DG. 17 August 2010.</ref>
==Cell types==
Follicular dendritic cells:<ref name=pmid9258622>{{cite journal |author=Wright CA, Nayler SJ, Leiman G |title=Cytopathology of follicular dendritic cell tumors |journal=Diagn. Cytopathol. |volume=17 |issue=2 |pages=138–42 |year=1997 |month=August |pmid=9258622 |doi= |url=http://www3.interscience.wiley.com/journal/57062/abstract?CRETRY=1&SRETRY=0}}</ref>
*Classically found in pairs.
*Large nucleus with:
**Basketweave chromatin pattern.
**Small central nucleolus.
Lymphocytes:
*See ''B lymphocytes'' section.


==B cell cycle==
===B lymphocytes===
B cell cycle/maturation:<ref>Wheater's FH. 4th Ed. P.210.</ref>
*B cells are best understood in the context of their maturation.
 
B cell cycle/maturation:<ref name=Ref_WFH4_210>{{Ref WFH4|210}}</ref>
#Centroblast (CB):
#Centroblast (CB):
#*Appearance:<ref>URL: [http://www.healthsystem.virginia.edu/internet/hematology/HessEDD/BenignHematologicDisorders/normal-hematopoietic-cells/Secondary-lymphoid-organs-and-tissues.cfm http://www.healthsystem.virginia.edu/internet/hematology/HessEDD/BenignHematologicDisorders/normal-hematopoietic-cells/Secondary-lymphoid-organs-and-tissues.cfm]. Accessed on: 31 January 2010.</ref>
#*Appearance:<ref>URL: [http://www.healthsystem.virginia.edu/internet/hematology/HessEDD/BenignHematologicDisorders/normal-hematopoietic-cells/Secondary-lymphoid-organs-and-tissues.cfm http://www.healthsystem.virginia.edu/internet/hematology/HessEDD/BenignHematologicDisorders/normal-hematopoietic-cells/Secondary-lymphoid-organs-and-tissues.cfm]. Accessed on: 31 January 2010.</ref>
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Notes:
Notes:
*Immunoblasts may be T cells or B cells; it is not possible to tell on morphologic grounds, i.e. without IHC.
*Immunoblasts may be T cells or B cells; it is not possible to tell on morphologic grounds, i.e. without IHC.
*Memory device: centro'''''cytes''''' are ''light'' (it nearly rhymes).


Image:
Image:
*[http://www.healthsystem.virginia.edu/internet/hematology/HessEDD/BenignHematologicDisorders/normal-hematopoietic-cells/Secondary-lymphoid-organs-and-tissues.cfm Lymphoid organs (healthsystem.virginia.edu)].
*[http://www.healthsystem.virginia.edu/internet/hematology/HessEDD/BenignHematologicDisorders/normal-hematopoietic-cells/Secondary-lymphoid-organs-and-tissues.cfm Lymphoid organs (healthsystem.virginia.edu)].


==Cell types==
===Cell types - table===
Follicular dendritic cells:<ref name=pmid9258622>{{cite journal |author=Wright CA, Nayler SJ, Leiman G |title=Cytopathology of follicular dendritic cell tumors |journal=Diagn. Cytopathol. |volume=17 |issue=2 |pages=138–42 |year=1997 |month=August |pmid=9258622 |doi= |url=http://www3.interscience.wiley.com/journal/57062/abstract?CRETRY=1&SRETRY=0}}</ref>
 
*Classically found in pairs.
{| class="wikitable"
*Large nucleus with:
! Cell
**Basketweave chromatin pattern.
! Location
**Small central nucleolus.
! Key feature
! Other morphologic
! IHC
! Other
! Image
|-
| Centroblast
| germinal center
| nucleolus
| large cell, darker staining
| CD10+, BCL6+ ???
| other ?
| image ?
|-
| Centrocyte
| germinal center
| cleavage
| small cell, light staining
| CD10+, BCL6+ ???
| other ?
| image ?
|-
| Follicular dendritic cell (FDC)
| germinal center
| mesh-like chromatin, usu. beside another one
| large cell, unremarkable/small nucleolus
| CD21+, [[CD23]]+
| other ?
| image ?
|-
| Tingible body macrophage
| germinal center
| abundant bubbly pale cytoplasm (with junk)
| large cell
| CD68+
| other ?
| image ?
|-
<!-- | cell
| location
| key feature
| other morphologic
| IHC
| other
| image -->
|}
 
 
=Pathology=
{{Main|Lymph node pathology}}
LNs are very important in [[cancer staging]] and are, in many contexts, sampled routinely. 
 
===Sentinel lymph nodes===
*Abbreviated ''SLN''.
*LN sampling is associated with morbidity; thus, selective LN sampling is preferred.
*The most important LNs in a LN chain, in the context of [[cancer]], are the ones that are adjacent to the tumour; these are known as '''sentinel lymph nodes'''.
*In lymph node positive disease, the most radioactive lymph node may be negative; this happens ~13% of the time in melanoma.<ref name=pmid11314933>{{Cite journal | last1 = McMasters | first1 = KM. | last2 = Reintgen | first2 = DS. | last3 = Ross | first3 = MI. | last4 = Wong | first4 = SL. | last5 = Gershenwald | first5 = JE. | last6 = Krag | first6 = DN. | last7 = Noyes | first7 = RD. | last8 = Viar | first8 = V. | last9 = Cerrito | first9 = PB. | title = Sentinel lymph node biopsy for melanoma: how many radioactive nodes should be removed? | journal = Ann Surg Oncol | volume = 8 | issue = 3 | pages = 192-7 | month = Apr | year = 2001 | doi =  | PMID = 11314933 }}</ref>
 
Use:
*[[Sentinel lymph node sampling in breast cancer|Breast cancer]] - very common.
*[[Malignant melanoma#Sentinel lymph node panel|Malignant melanoma]] - first context in which SLN sampling was done.


Lymphocytes
===Lymph node metastasis===
*See ''B cell cycle'' section.
{{Main|Lymph node metastasis}}
*Cancer that has spread to a lymph node.


==See also==
=See also=
*[[Haematopathology]].
*[[Haematopathology]].
*[[Lymph node pathology]].
*[[Basics]].
*[[Basics]].


==External links==
=References=
{{reflist|2}}
 
=External links=
*[http://pleiad.umdnj.edu/hemepath/normal_node/normal_node.html Lymph node architecture (umdnj.edu)].
*[http://pleiad.umdnj.edu/hemepath/normal_node/normal_node.html Lymph node architecture (umdnj.edu)].
==References==
{{reflist|2}}


[[Category:Haematopathology]]
[[Category:Haematopathology]]

Latest revision as of 19:03, 15 October 2023

Lymph nodes, abbreviated LNs, are very important in pathology. They are the site of metastases and/or may be the site of a primary tumour, i.e. lymphoma.

Haematopathology and lymphoma is dealt with in the haematopathology article. This article covers the basics of lymph nodes. Lymph node pathology is dealt with in the lymph node pathology article. Grossing is covered in lymph node grossing.

Clinical

Normal (clinical)

  • Round.
  • "Soft".
  • Mobile.

Pathologic (clinical) - associations

  • Rubbery = suggestive of lymphoma.
  • Tender (hurts when ya touch it) = suggestive of infection.
  • Fixed (immobile) = suggestive of cancer, usually carcinoma.
  • Hard = suggestive of cancer.
  • "Large" - cancer or infection.
    • What qualifies for "large" depends on the location in the body.

Radiologic

  • Ellipical (as opposed to spherical) = may be cancer.
  • "Large" = could be cancer or infection.
    • What qualifies for "large" depends on the location in the body.

Gross pathologic exam

Normal:

  • Firm (relative to adipose tissue).
  • Glistening surface when cut.

Pathologic:

  • White lesions, especially irregular = suggestive of carcinoma.
  • White, glistening, with lobulated surface - "fish flesh" = suggestive of lymphoma.

Microscopic

Lymph node architecture

Lymph node architecture (superficial to deep):[2]

  • Capsule.
  • Subcapsular sinus.
    • Place where metastatic cells often are found.
    • In a normal LN the vessels should be "open", i.e. have a discernible lumen.
  • Cortex:
    • Follicles (superficial).
    • Paracortex (deep).
    • Cortical sinuses.
  • Medulla:
    • Medullary cords.
    • Medullary sinuses.

Notes:

  • Trabeculae - segment the LN radially, i.e. are spoke-like structures.

Lymph node follicles

Types of follicles:[3]

  1. Primary follicle - no germinal center (pale area).
  2. Secondary follicle - have a germinal center (pale area) and mantle zone (rim of darker staining lymphocytes).

Germinal centre

Architecture:

  • Paler at capsular aspect.
  • Darker at medullary aspect.

Image:

Location and cell types

Germinal centers:[5]

  • Site of B lymphocyte proliferation; follicle center cells.
    • Centroblasts - usually superficial aspect. (??? deeper ???)
      • Darker, larger, nucleoli.
    • Centrocytes (mid germinal center).
      • Cells with cleavage.
    • Centrocytes (transforming to immunoblasts) - usually deeper aspect. (??? superficial ???)
      • Cells with cleavage.
  • Tingible body macrophages - mid germinal center.
  • Follicular dendritic cells.

Paracortex:[6]

  • Site of T lymphocytes.
  • Interdigitating dendritic cell.

Medullary cords (site of immunoglobulin synthesis):

  • B lymphocytes.
  • Plasma cells.

Mantle zone:

  • Memory B cells.
  • Usually asymmetrical; thicker, i.e. more mantle cells, at capsular aspect.[7]

Cell types

Follicular dendritic cells:[8]

  • Classically found in pairs.
  • Large nucleus with:
    • Basketweave chromatin pattern.
    • Small central nucleolus.

Lymphocytes:

  • See B lymphocytes section.

B lymphocytes

  • B cells are best understood in the context of their maturation.

B cell cycle/maturation:[5]

  1. Centroblast (CB):
    • Appearance:[9]
      • Large cells.
      • Round nucleus, dark.
      • Nucleolus (nucleoli).
      • Mitotically active.
    • Location:
      • Medullary aspect of germinal center.
  2. Centrocytes (CC), AKA cleaved cells.
    • Appearance:
      • Cleaved nucleus
      • NOT mitotically active.
    • Location:
      • Mid germinal center.
  3. Immunoblasts or memory B cells.
    • Appearance:
      • Small lymphocytes.
    • Location:
      • Peripheral blood, mantle zone.

Notes:

  • Immunoblasts may be T cells or B cells; it is not possible to tell on morphologic grounds, i.e. without IHC.
  • Memory device: centrocytes are light (it nearly rhymes).

Image:

Cell types - table

Cell Location Key feature Other morphologic IHC Other Image
Centroblast germinal center nucleolus large cell, darker staining CD10+, BCL6+ ??? other ? image ?
Centrocyte germinal center cleavage small cell, light staining CD10+, BCL6+ ??? other ? image ?
Follicular dendritic cell (FDC) germinal center mesh-like chromatin, usu. beside another one large cell, unremarkable/small nucleolus CD21+, CD23+ other ? image ?
Tingible body macrophage germinal center abundant bubbly pale cytoplasm (with junk) large cell CD68+ other ? image ?


Pathology

LNs are very important in cancer staging and are, in many contexts, sampled routinely.

Sentinel lymph nodes

  • Abbreviated SLN.
  • LN sampling is associated with morbidity; thus, selective LN sampling is preferred.
  • The most important LNs in a LN chain, in the context of cancer, are the ones that are adjacent to the tumour; these are known as sentinel lymph nodes.
  • In lymph node positive disease, the most radioactive lymph node may be negative; this happens ~13% of the time in melanoma.[10]

Use:

Lymph node metastasis

  • Cancer that has spread to a lymph node.

See also

References

  1. Bailey, D. 5 August 2010.
  2. Young, Barbara; Lowe, James S.; Stevens, Alan; Heath, John W.; Deakin, Philip J. (2000). Wheaters Functional Histology (4th ed.). Churchill Livingstone. pp. 206-8. ISBN 978-0004881973.
  3. Young, Barbara; Lowe, James S.; Stevens, Alan; Heath, John W.; Deakin, Philip J. (2000). Wheaters Functional Histology (4th ed.). Churchill Livingstone. pp. 208. ISBN 978-0004881973.
  4. URL: http://www.pathpedia.com/education/eatlas/histology/lymph_node/images.aspx. Accessed on: 29 October 2012.
  5. 5.0 5.1 Young, Barbara; Lowe, James S.; Stevens, Alan; Heath, John W.; Deakin, Philip J. (2000). Wheaters Functional Histology (4th ed.). Churchill Livingstone. pp. 210. ISBN 978-0004881973.
  6. Young, Barbara; Lowe, James S.; Stevens, Alan; Heath, John W.; Deakin, Philip J. (2000). Wheaters Functional Histology (4th ed.). Churchill Livingstone. pp. 211. ISBN 978-0004881973.
  7. DG. 17 August 2010.
  8. Wright CA, Nayler SJ, Leiman G (August 1997). "Cytopathology of follicular dendritic cell tumors". Diagn. Cytopathol. 17 (2): 138–42. PMID 9258622. http://www3.interscience.wiley.com/journal/57062/abstract?CRETRY=1&SRETRY=0.
  9. URL: http://www.healthsystem.virginia.edu/internet/hematology/HessEDD/BenignHematologicDisorders/normal-hematopoietic-cells/Secondary-lymphoid-organs-and-tissues.cfm. Accessed on: 31 January 2010.
  10. McMasters, KM.; Reintgen, DS.; Ross, MI.; Wong, SL.; Gershenwald, JE.; Krag, DN.; Noyes, RD.; Viar, V. et al. (Apr 2001). "Sentinel lymph node biopsy for melanoma: how many radioactive nodes should be removed?". Ann Surg Oncol 8 (3): 192-7. PMID 11314933.

External links