Lymphoreticular System

Question 1

The Innate immune system is made up of what cells?

Answer 1

Macrophage, Natural Killer Cell, Dendritic cell, Neutrophil, Eosinophil, Basophil

Question 2

The Adaptive immune system is made up of what cells?

Answer 2

B cell –> Antibodies
T cell –> CD4+ T cell, CD8+ T cell

Question 3

What cells overlap between the Adaptive and innate immune system?

Answer 3

T-Cell
Natural Killer T cell

Question 4

The lymphoreticular system is made up of…

Answer 4

thymus, spleen, LN’s, Mucosa-associated lymphoid tissue (MALT), tonsils, bone marrow

Question 5

What cells are present within the outer cortex of the thymus?

Answer 5

Immature T-cells migrate to thymus for proliferation & maturation

Question 6

What cells are present within the inner medulla of the thymus?

Answer 6

Defective mature T-cells move to blood

Question 7

What age of life is the thymus important in the lymphoreticular system?

Answer 7

Foetal life

Question 8

The thymus is associated w/ what type of immunity and lymphocytes?

Answer 8

Cell-mediated immunity
Production of helper (Th 1&2) and T-regulatory lymphocytes

Question 9

What pathologies affect the thymus?

Answer 9

Thymic mass (thymic lymphoma, thymoma, other epithelial tumours)
Benign thymic hyperplasia
Cyst
haemorrhage - acute
thymic atrophy

Question 10

What clinical signs may be present if there is a thymus pathology?

Answer 10

Resp signs due to pleural effusion
Myasthenia gravis (canine thymoma)
Hypercalcemia & assoc’d signs (lethargy, PU/PD)

Question 11

How would you approach thymus pathologies diagnostically?

Answer 11

Good clin Hx, Physical exam
General blood panel (hematology, biochemistry, urinalysis)
Imaging (chest rads, chest ultrasound, thx CT)
Sampling (cytology, Bx)

Question 12

Lymphomas can arise in the thymus through

Answer 12

malignant transformation of lymphocytes

Question 13

Thymomas arise from…

Answer 13

neoplastic epithelium

Question 14

Describe thymomas on cytology

Answer 14

Monomorphic population of small lymphocytes or mixed lymphoid cell population
Small amt of mast cells interspersed among lymphocytes

Question 15

What cells are not typically seen with lymphoma?

Answer 15

Mast cells & melanocytes

Question 16

Why is it difficult to distinguish between thymoma and LSA on FNA?

Answer 16

Thymic epithelial cells do not readily exfoliate & rare to see on FNA

Question 17

How should you differentiate from Thymoma and LSA?

Answer 17

PARR - PCR for antigen receptor rearrangements
Flow cytometry
Histopath +/- Immunohistochem

Question 18

Describe the structure of the spleen.

Answer 18

Capsule - subject to action of the ANS
Red Pulp - RBC component
White Pulp - immune regulation

Question 19

Describe the functions of the spleen.

Answer 19

• Assoc’d w/ humoral-mediated immunity –> production of B-lymphocytes & antibodies
• macrophages filter blood for removal of infectious agents
• Removal of old/abnormal RBC’s w/ inclusions or coated w/ antibody & complement
• Storage of RBCs, platelets, Fe
• Extramedullary haematopoiesis (EMH) in presence of anemia

Question 20

What vascular pathology(ies) might occur?

Answer 20

Thrombus

Question 21

What inflammatory/infection splenic pathologies might occur?

Answer 21

• splenitis
• splenic abscess
• splenic granuloma

Question 22

What traumatic splenic pathologies may occur?

Answer 22

• Haematoma
• Splenic torsion

Question 23

What anomaly in the spleen may occur?

Answer 23

Splenic cyst

Question 24

What metabolic pathologies can occur in the spleen?

Answer 24

Splenic congestion

Due to CHF, PSS, Drugs, Portal hypertension

Question 25

Are there any idiopathic pathologies of the spleen?

Answer 25

No

Question 26

What neoplastic pathologies of the spleen can occur?

Answer 26

* Hematopoietic tumors * sarcoma (HSA) * metastasis

Question 27

What degenerative pathologies of the spleen may occur?

Answer 27

* Myelolipomas * Nodular lymphocytic hyperplasia

Question 28

What are some things you might look for on a physical exam for splenic pathologies?

Answer 28

* Abdominal effusion * VPCs * Pain

Question 29

What are you looking for on abdominal palpation that may indicate a splenic pathology?

Answer 29

* Splenomegaly * Altered shape, irregular margins * altered consistency

Question 30

What is the general location of the spleen?

Answer 30

Located Left cranial abdomen and is associated with greater curvature of the stomach

Question 31

What is the normal shape of the spleen?

Answer 31

Smooth outer capsule, soft parenchyma

Question 32

When would a spleen cause regenerative anemia?

Answer 32

Splenic rupture or hemoabdomen

Question 33

What might you see on blood smear if there is a pathology in the spleen?

Answer 33

Schistocytes

Question 34

Coagulopathies are seen on bloods and are related to the spleen when what pathologies may be occurring?

Answer 34

DIC Hypercoagulopathic State

Question 35

What imaging might you use for looking at the spleen?

Answer 35

Rads, Ultrasound, CT

Question 36

When might you do splenic aspirates under ultrasound?

Answer 36

Hyperechoic nodules &/or mixed echogenicity

Question 37

How might you take a biopsy of the spleen?

Answer 37

Surgical of laparoscopic excisional biopsy (+/- impression smear from sample)

Question 38

What additional tests might be used to diagnose splenic pathologies?

Answer 38

* PARR, immuncytochemistry * +/- culture & susceptibility if suspect cystic lesion or abscess

Question 39

What is the most common canine splenic neoplasm?

Answer 39

Splenic hemangiosarcoma

Question 40

What canine breeds are predisposed to canine splenic HSAs?

Answer 40

GSD Golden retrievers

Question 41

Canine Splenic HSAs are associated with...

Answer 41

* Coagulopathies (DIC) * Arrhythmias (VPCs) * Sudden collapse due to rupture - hemoabdomen * Concurrent RHS atrial mass tumor

Question 42

What essential pre-operative stabilisation must occur if there is a canine splenic HSA?

Answer 42

if hemoabdomen is present, give fluids &/or transfusions

Question 43

Can you determine HSA being benign or malignant on ultrasound appearance ?

Answer 43

No

Question 44

Describe the structure and function of lymph nodes

Answer 44

* Outer cortex - Lymphoid follicles; inner germinal centre is the site for B-cell proliferation; outer edge has more T-cells * Inner medulla - cords of lymphocytes, macrophages, plasma cells; has activated B-cells

Question 45

What peripheral LN's are important to know and feel on physical exam?

Answer 45

* Submandibular * Prescapular * Popliteal * Inguinal & axillary (if enlarged)

Question 46

What are you looking for when asking about Hx or doing a physical exam?

Answer 46

* Travel Hx * Concurrent systemic clinical signs * painful around area * recent trauma, Sx, bite, wound * other lesions? * signle or multiple LN's involved? * Measure & record LN size/consistency

Question 47

Lymphadenopathy can be...

Answer 47

Non-neoplastic or neoplastic

Question 48

What are forms of non-neoplastic lymphadenopathy?

Answer 48

* Lymphoid Hyperplasia * Inflammation - Lymphadenitis

Question 49

What neoplastic lymphadenopathies may occur?

Answer 49

* Primary - Lymphoma * Secondary - Metastatic Dz

Question 50

Compare and contrast FNA and Excisional/Tru-cut Bx

Answer 50

**FNA** * Easy to perform, quick, conscious or sedated, eval cell morphology, may not be representative, low cellularity & higher risk blood contamination, less complications, cheap **Bx** * Req's experience, GA/deep sedation, eval morpholgoy & structure, larger tissue sample, infection, wound dehiscence, peripheral oedema, more costly

Question 51

Lymphoid hyperplasia is what kind of process?

Answer 51

Reactive

Question 52

If you did an FNA on a lymph node with hyperplasia, what might you see?

Answer 52

Predominantly small cell lymphocytes <20% med to large lymphocytes Plasma cells 5-20%

Question 53

If you did an FNA on a patient with lymphadenitis, what might you see?

Answer 53

* 90% well-differentiated small cell lymphocytes * Up to 10% med to large lymphocytes * Occasional plasma cells, histiocytes, neutrophils, mast cells

Question 54

What is the main differential for lymphoma?

Answer 54

Generalised lymphadenopathy

Question 55

High-grade LSA will look like what on cytology?

Answer 55

>50% med to large lymphocytes

Question 56

What are the 2 main types of lymphoma?

Answer 56

Diffuse large B-cell LSA Small cell T-zone lymphoma

Question 57

What tests are required to differentiate between lymphoid hyperplasia and low-grade LSA?

Answer 57

* Histopath (excisional vs incisional wedge Bx/Tru-cut) * immunophenotyping (immunocyto- or histochem) * PARR * flow cytometry (expression of specific cell markers)