Changes

==Reactive Lymph Nodes==

==Reactive Lymph Nodes==

Lymph nodes demonstrate Hyperplasia as an immunological response to antigens; cells proliferate in the cortex of the node and germinal centre activity results in multiplication of cells in the thymus-dependent area (paracortex). Newly formed plasma cells accumulate in the medullary cords and macroscopically a bulging white cortex is seen which may almost obliterate the medulla

Lymph nodes demonstrate hyperplasia as an immunological response to antigens; cells proliferate in the cortex of the node and germinal centre activity results in multiplication of cells in the thymus-dependent area (paracortex). Newly formed [[B cell differentiation|plasma cells]] accumulate in the medullary cords and macroscopically a bulging white cortex is seen which may almost obliterate the medulla

==Lymphadenitis==

==Lymphadenitis==

oedema or leukocyte (neutrophil) accumulation. Pyogenic organisms can cause abscessation, and necrosis within the node.

oedema or leukocyte (neutrophil) accumulation. Pyogenic organisms can cause abscessation, and necrosis within the node.

Lymphangitis is a more general term refering to an inflammation of the lymphatic system.

Lymphangitis refers to an inflammation of the lymphatic vessels.

==Haemal Lymph Nodes==

==Haemal Lymph Nodes==

*these two should not be confused since the prognosis is very different following surgery  

*these two should not be confused since the prognosis is very different following surgery  

===Emphysema===

===Emphysema===

Interstitial emphysema can occur in the respiratory lymph nodes and is common in cases of dyspnoea. This condition is seen most commonly in the bovine lung which, due to the well developed pulmonary lobulation and extenive loose interstitial lung tissue permits a collection of gas bubbles in the bronchial and mediastinal lymph nodes. Gas travels to these nodes after gaining entry to the many lymphatic vessels present in the interstitial tissue  

Interstitial emphysema can occur in the respiratory lymph nodes and is common in cases of dyspnoea. This condition is seen most commonly in the bovine lung which, due to the well developed pulmonary lobulation and extensive loose interstitial lung tissue permits a collection of gas bubbles in the bronchial and mediastinal lymph nodes. Gas travels to these nodes after gaining entry to the many lymphatic vessels present in the interstitial tissue

 

===Neoplasia===

===Neoplasia===

Primary lymph node tumours include lymphosarcoma (lymphoma) which affect lymphoid cells with lymph node enlargement. The nodes become smooth, pale and hemogenous but may have areas of necrosis; this condition may cause pseudo-hyperparathyroidism.

Primary lymph node tumours include lymphosarcoma (lymphoma) which affect lymphoid cells with lymph node enlargement. The nodes become smooth, pale and hemogenous but may have areas of necrosis; this condition may cause pseudo-hyperparathyroidism.

   

   

Secondary tumours; the lymph nodes are often involved in the spread of tumours by extension or metastasis and are usually carcinomas

Secondary tumours; the lymph nodes are often involved in the spread of tumours by extension or metastasis and are usually carcinomas