Lecture 1 and 2 - Lymph nodes

What does lymphadenomegaly mean?

Enlarged lymph node

What does lymphadenitis mean?

Inflamed lymph node

What does lymphadenopathy mean?

Diseased lymph node

What are four things that can occur in response to injury?

1. Hyperplasia

2. Inflammation

3. Neoplasia

4. Atrophy

What are three types of hyperplasia that can occur in the lymph nodes? What cell type do they affect?

1. Sinus histiocytosis - macrophages

2. Follicular hyperplasia - B cells (plasma cells)

3. Paracortical hyperplasia - T cells

What does acute lymphadenitis look like grossly?

-Red, enlarged, and edematous

-Soft

-Taut capsule

-Bulges on cut surface

-Necrotic/suppurative areas (usually from bacteria)

-± hemorrhage

What are the clinical signs of streptococcus equi ssp. equi?

-Large abscesses on lymph nodes

-Guttural pouch empyema (collection of pus)

-Compression of pharynx (respiratory stridor)

-Dysphagia

What are two sequalae commonly seen with streptococcus equi ssp. Equi?

1. Bastard strangles - metastatic abscess formation in other organs

2. Type III hypersensitivity - causes purpura hemorrhagica and necrotizing vasculitis following reinfection or vaccination

What are the inflammatory types associated with chronic lymphadenitis?

-Chronic suppurative inflammation (abscess)

-Granulomatous inflammation

What type of inflammation does rhodococcus equi cause?

Pyogranulomatous enterotyphlocolitis and lymphadenitis

What type of inflammation does Johne’s disease?

Granulomatous enteritis and lymphadenitis of mesenteric lymph nodes

What type of inflammation does tuberculosis cause? What is a key sign of tuberculosis in cattle?

-Granulomatous inflammation

-Mineralized lymph nodes

What are three fungal infections that can cause chronic lymphadenitis?

1. Cryptococcosis (dog)

2. Histoplasmosis

3. Blastomycosis

What does porcine circovirus cause? What are three PCV-associated diseases?

-Causes lymphadenitis

1. PCV2

2. Postweaning multisystemic wasting syndrome (PMWS)

3. Porcine dermatitis and nephropathy syndrome (PDNS)

What are common signs associated with postweaning multisystemic wasting syndrome (PMWS)?

-Poor body condition

-Interstitial pneumonia

-Enlarged lymph nodes with granulomatous lymphadenitis

What are common signs associated with porcine dermatitis and nephropathy syndrome (PDNS)?

-Necrotizing vasculitis

-Kidney and skin affected

-Enlarged lymph nodes with granulomatous lymphadenitis

What is the primary lymph node neoplasia? What are the two common types?

-Lymphoma

-B cell or T cell

What is multicentric lymphoma? What species is it most common in?

-Multiple lymph nodes involved

-Most common in dogs

What is alimentary lymphoma? What species is it most common in?

-Involves GI tract and regional lymph nodes

-Most common in cats

What is mediastinal lymphoma? Who does it infect? What is the origin?

-Involves mediastinum or thymus

-Affects young animals

-T cell origin

What is cutanous lymphoma?

Skin and draining lymph nodes

What virus is lymphoma associated with in cattle? Where are the common sites?

-Bovine leukosis virus (BLV)

-Common sites = HULA (heart, uterus, lungs, abomasum)

What can cause lymph node atrophy?

-Viral infections (ex. distemper)

-Malnutrition and cachexia

-Glucocorticoids

-Aging

-Radiation

What is the importance of mucosa-associated lymphoid tissue (MALT)? Which ones are targeted in pigs with CSF? Which ones are targeted in BVDV and CDV?

-Act like little lymph nodes and can serve as an entry portal for many diseases

-CSF pigs = tonsils

-BVDV and CDV = peyers patches