Pathology of Lymph Nodes and Spleen

Question 1

Common cause of acute cervical lymphadenitis?

Answer 1

Microbial infections of the teeth or tonsils

Question 2

What is the structure of the white pulp follicles?

Answer 2

Artery with an eccentric collar of T lymphocytes (periarteriolar lymphatic sheath).

Question 3

What are the four functions of the spleen?

Answer 3

1) Phagocytosis of blood cells and particulate matter
2) Antibody production
3) Haematopoiesis
4) Sequestration of formed blood elements

Question 4

Where does pitting of RBCs occur?

Answer 4

In splenic macrophages

Question 5

What is pitting of RBCs?

Answer 5

Excision of inclusions in RBCs by splenic M0 e.g.

• Heinz bodies
• Howell-Jolly bodies

Question 6

How do T lymphocytes in the spleen recognise antigens and trigger production of antibodies?

Answer 6

Dendritic cells in the periarterial lymphatic sheath trap antigens and present them to T lymphocytes –> interact with B cells at edges of white pulp follicles –> generate antibody secreting plasma cells.

Question 7

What is the role of the spleen in haematopoiesis?

Answer 7

• Generally ceases pre birth
• Can reactivate in severe anemia
• Prominent site of extra medullary haemopoiesis in myeloproliferative disorders (e.g. CML)

Question 8

Effect of spleen in sequestration of formed blood elements?

Answer 8

• Usually only 30-40mL RBCs
• 30-40% platelets
• With splenomegaly, sequestered volume greatly increases: can induce thrombo-/leuko-cytopenia

Question 9

What is the clinical manifestation of splenic insufficiency (i.e.post splenectomy / auto-infarction)?

Answer 9

Increased susceptibility to sepsis causes by encapsulated bacteria e.g.

• pneumococcus
• meningococcus
• H. influenzae.

Question 10

Symptoms of splenomegaly?

Answer 10

• Dragging sensation LUQ

- Compression of stomach -> discomfort after eating

Question 11

What characterises hypersplenism?

Answer 11

-Leukopenia
-Thrombocytopenia
-Anemia
(alone or in combination) ?due to increased sequestration of formed blood elements > M0 phagocytosis.

Question 12

Morphology of long standing congestive splenomegaly?

Answer 12

• Large spleen (1-5kg)
• Organ firm
• Capsule thick and fibrous
• Red pulp congested initially, becomes increasingly fibrotic and cellular
• Deposition of collagen in BM of sinusoids
• Slowing of blood flow from cords > sinusoids prolongs exposure of cells to M0 > hypersplenism

Question 13

Cause of splenic infarcts?

Answer 13

Occlusion of splenic artery or its branches.

-common site of emboli (usually from heart)

Question 14

Morphology of splenic infarcts?

Answer 14

-Pale, wedge shaped, subcapsular infarcts
-overlying capsule often covered with fibrin
-heals by scarring
If septic: + suppurative necrosis.

Question 15

What are spleniculi?

Answer 15

• Accessory spleens
• Present in 20-35% post mortems
• Small, spherical structures histologically and functionally identical to N spleen

Question 16

When are spleniculi clinically significant?

Answer 16

-Signficant in haematologic disorders e.g. hereditary spherocytosis, immune thrombocytopenic purpura.
Splenectomy is treatment: failure to remove spleniculi may negate this.

Question 17

Cause of spontaneous splenic rupture without trauma?

Answer 17

Minor physical insult to a spleen made fragile by condition e.g. :
-infectious mono
-malaria
-typhoid fever
-lymphoid neoplasms
Cause rapid splenic enlargement, thin capsule susceptible to rupture.