Category:Lymph Nodes

Category:Lymph Node Responses in Disease

Role of the Lymph Node in Inflammation

Back to Inflammation - Pathology

Diseases Involving Reactive Nodes

Parasitic Diseases

bovine parasitic bronchitis

ostertagiasis

fascioliasis

Bacterial Diseases

clostridial

Diseases Involving Both Reactive Nodes and Lymphadenitis

Tuberculosis - Cattle

viz. brucellosis and Johne's disease

• chronicity is caused by persistence of intacellular bacteria in lymph node macrophages
• Type IV hypersensitivity, but does not result in visible necrosis as in TB

Johne's disease

Actinobacillosis

Actinomycosis

Equine strangles

• acute inflammation
• produce pyogenic or necrotic foci in the drainage nodes
• involves submaxillary nodes

Streptococcal adenitis or head gland disease

• dogs
• acute inflammation as in above

Diseases Parasitising the Lymphocytes

• organism grows in the lymphocytes and ruptures them
• if large infecting dose

- may be rapidly fatal since animal may no tb e able to mount an immunological attack

• if smaller infecting dose

- loss of mature lymphocytes causes a dramatic stimulation of the remaining lymphocyte precursors

- node hyperplasia follows

- competition between lymphocytolysis by the organism and lymphocyte production by the nodes

- clinically

- may be swelling of the node at one stage and reduction in size at another

canine distemper

• virus

swine fever

• virus

bovine east coast fever

• protozoan

Leishmaniasis in the dog

Other Lymphadenopathy

Lymph node pigmentation

• Lungs

- anthracosis

- carbon derived from soot finds its way to the local nodes in macrophages

• Skin

- dermatopathic lymphadenopathy or melanic reticulosis

- in pigmented animals, especially black dogs

- chronic inflammatory skin conditions lead to melanin deposition in hyperplastic nodules

- also occurs in nodes draining skin melanomas where the pigment may be the result of skin ulceration or secondary tumour deposit

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

Emphysema

• interstitial emphysema

- common in cases of dyspnoea

- more commonly affects bovine lung

- due to well developed pulmonary lobulation and hence much loose interstitial lung tissue

• collection of gas bubbles in bronchial and mediastinal lymph nodes

- gas travels to these nodes after gaining entry to the many lymphatic vessels present in the interstitial tissue

Neoplasia

• Primary tumours
  • Lymphosarcoma (lymphoma)

- of lymphoid cells with lymph node enlargement

- smooth, pale hemogenous but may have areas of necrosis

- may cause pseudo-hyperparathyroidism

• Secondary tumours

- nodes often involved in the spread of tumours by extension or metastasis

- usually carcinomas

Haemal Lymph Nodes

• ruminants only
• small; dark red/brown
• develop during foetal life

- lymph node primordia which lose their lymph vessles

- receive all cells and antigen from the BLOOD

• functional significance unclear
• probably respond to blood-borne antigen