pulmonary TB

Question 1

TB Caused by

Answer 1

mycobacterium

Question 2

mycobacterium is resistant to

Answer 2

drying thus can survive in the

atmosphere for weeks

Question 3

Susceptibility factors to TB include:

Answer 3

age (children, elderly due to depressed immunity)
- immunity: People who are immuno-compromised have high susceptibility,
Diabetic, AIDS, malnutrition (Kwashiorkor in children), immunosuppressive
therapy (cancer treatment)
- Silicosis of the lung increases the risk of TB.
- Immunisation: All new-borns get BGC vaccination

Question 4

Host Response to TB

Answer 4

Bacillus enters the lung.
• First response is neutrophils. Neutrophils are not capable of killing
the bacteria so they disappear.
• A few days later, macrophages influx. These ingest the bacteria but
also cannot kill them.
• Macrophages eventually die leaving the bacilli alive and well.
• Lymphocytes influx. Lymphocytes release lymphokines which attract
more macrophages.
• Lots of macrophages then enter the area
These macrophages then become larger and they change their
appearance to epithelioid histiocytes. Their function changes from
ingestion to secretion.
• The epithelioid histiocytes release substances which are more
efficient killers of these bacteria.
• This results in granuloma formation. Macrophages may fuse to form
Langhan’s giant cells.
• The central portion of the granuloma may undergo
necrosis. Typically caseation. Macroscopically this is visible as
white spots on the lung called tubercles

Question 5

Primary TB

Answer 5

Occurs when the individual is exposed for the first time to mycobacterium
tuberculosis

Question 6

lesion site and it name

Answer 6

site of the bacillus entry. (Invariably in
the lungs but can also occur in the GIT, tonsils, skin (rarely), This lesion is the Ghon focus
• In the lungs, there is a typical site. In the right lung it is the lower part of the
upper lobe and upper part of the middle lobe.
• In the left lung it is the lower part of the upper lobe or upper part of the
lower lobe. It is subpleural

Question 7

Ghon Complex

Answer 7

Ghon focus+ Hilar lymphadenopathy

Question 8

Caseative granulomas / necrotizing granulomatous inflammation

Answer 8

Concentric arrangement
• Caseative necrosis centrally
• Surrounded by epithelioid histiocytes
• Peripheral cuff of lymphocytes

Question 9

Multinucleated giant cells are present in the granulomas

Answer 9

Langhans type

• Foreign body-type

Question 10

Necrosis has characteristic appearance

Answer 10

Grossly –cream-white, semisolid and resemble cottage cheese (‘caseation’)
• Microscopically- eosinophilic, bland and structureless with karyorrhectic debris
• Surviving bacilli often seen at the periphery of the lesion

Question 11

Ziehl-Neelsen Stain

Answer 11

n is positive

for acid-fast bacilli

Question 12

If the Ghon focus doesn’t heal

Answer 12

, it may rupture into the pleural cavity to cause a

TB pleurisy with associated effusion

Question 13

TB broncho-pneumonia.

Answer 13

The lymph node may rupture into the bronchus
and spread along the bronchus into the bronchioles then into the surrounding
lung tissue

Question 14

TB

pericarditis

Answer 14

Lymph nodes may also rupture into the pericardial space

Question 15

miliary TB.

Answer 15

lymph node can rupture into pulmonary vein to cause systemic dissemination

Question 16

TB peritonitis

Answer 16

Rupture of lymph nodes in the abdomen

Question 17

tabes mesenterica

Answer 17

The enlarged caseous mesenteric lymph nodes are termed

Question 18

intestinal TB

Answer 18

If the bacilli are swallowed

Question 19

Post-primary TB

Answer 19

This occurs in individuals who have previously been exposed to TB.

Question 20

Post-primary TB lesions

Answer 20

Found mainly in the upper lobes of the lungs especially the posterior
segment. The reason being a good ventilation with a relatively poor blood
supply which favours the bacilli

Question 21

haemoptysis

Answer 21

Rupture of the blood vessels due to erosion into them

Question 22

aneurysm

Answer 22

formed in the ruptured vessel

Question 23

TB pleurisy

Answer 23

he cavity may also rupture into the pleura

Question 24

Aspergillus

Answer 24

a fungus) commonly colonises the cavity forming a

fungal ball

Question 25

TB laryngitis

Answer 25

also occur due to coughing up the bacilli.

Question 26

Diagnosis of TB

Answer 26

Patients are usually emaciated.
• Fever
• Night sweats
• Cough persistently with haemoptysis.
• Enlarged lymph nodes (primary TB)
• Sputum exam in laboratory. Ziehl-Neelsen stain (ZN stain) is done.
Bacilli stain pink on a blue background. Mycobacterium tuberculosis is acid
fast. (AFB's = acid fast bacilli)