3. Chronic inflammation - diseases

Question 1

What are the possible complications of chronic inflammation?

Answer 1

1. fibrosis
2. impaired function (often secondary to fibrosis)
3. increased function - rare
4. atrophy
5. stimulation of immune response (macrophage - lymphocyte interaction)

Question 2

Give an example of chronic inflammation associated with increased function.

Answer 2

Thyrotoxicosis - overproduction of thyroxine - in Graves’ disease (autoantibodies against TSH receptors)

Question 3

Give an example of chronic inflammation leading to tissue atrophy.

Answer 3

Pernicious anaemia: gastric autoimmune disease (antibodies to parietal cells and intrinsic factor)… causes destruction of gastric mucosa.

Question 4

what is chronic cholecystitis and how is it caused

Answer 4

• chronic inflammation of gallbladder common bile duct
• due to repeated obstruction by gallstones
• causing fibrosis of gallbladder wall

Question 5

what is chronic gastritis and how is it caused

Answer 5

chronic inflammation of gastric mucosa caused by infection with Helicobacter pylori

Question 6

how does H. pylori cause chronic gastritis

Answer 6

1. directly damages epithelial cells
2. stimulates production of pro-inflammatory cytokines
3. increases acid secretion

Question 7

describe the microscopic features of chronic gastritis

Answer 7

1. presence of H. pylori organisms
2. mucosa chronic inflammation: in superficial epithelium and lamina propria
3. lamina propria fibrosis
4. mucosal atrophy
5. intestinal metaplasia

Question 8

which malignancies are associated with H. pylori gastritis

Answer 8

1- gastric adenocarcinoma

2- MALT lymphoma

Question 9

which cell type does Mtb initially infect and how does it survive

Answer 9

i) Mtb enters macrophages by endocytosis… replicates within phagosome - blocks phagolysosome fusion.
ii) proliferates in pulmonary alveolar macrophages and airspaces… bacteraemia… seeding of multiple sites (asymptomatic or mild flu-like illness)

Question 10

describe the immune response against Mtb infection

Answer 10

i) 3 wks after infection: T helper cell response against Mtb is mounted - produce IFNy… activates macrophages to become bactericidal… produce TNF.
ii) recruits monocytes with differentiate into epithelioid histiocytes… granuloma formaiton - contains illness in many.
iii) in some, infection progresses - immune response results in tissue destruction due to caseation and cavitation.

Question 11

what is the main microscopic feature of TB

Answer 11

tuberculous granuloma consisting of central caseous necrosis and Langhans giant cells

Question 12

what is the main macroscopic feature of TB

Answer 12

• GHON FOCUS (calcified tuberculous granuloma in lung)

- contained in a GHON COMPLEX (ghon focus + granulomas in hilar lymph node)

Question 13

what is a ranke complex

Answer 13

seen in healed primary TB - comprises a ghon focus and ipsilateral calcified hilar node

Question 14

what is miliary tuberculosis

Answer 14

disseminated TB throughout body (e.g. lungs, liver and spleen) resulting in small lesions esp. seen on chest x-ray

Question 15

what is Pott’s disease

Answer 15

TB in vertebrae

Question 16

what is scrofula

Answer 16

TB in cervical region

Question 17

what is sarcoidosis

Answer 17

autoimmune condition causing granuloma formation in various organs, esp. lungs and skin

Question 18

how is TB differentiated from sarcoidosis

Answer 18

TB

• caseous granuloma
• langhans giant cells
• X-ray to show Ghon lesions
• Acid-fast stain shows acid-fact bacilli

sarcoidosis

• non-caseating granuloma
• Langhans giant cells
• blood tests show high Ca2+ and high ACE levels

Question 19

what is liver cirrhosis

Answer 19

chronic liver inflammation associated with fibrosis… architecture disorganisation and attempted regeneration… cirrhosis and impaired function

Question 20

what are the common causes of liver cirrhosis

Answer 20

1- alcohol
2- HBV or HCV infection
3- immunological
4- fatty liver disease
5- drugs and toxins

Question 21

name 3 microscopic features of liver cirrhosis

Answer 21

1- fibrous CT surrounds regenerative nodules of heptocytes
2- bile duct proliferation
3- lymphocytes