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Lung Pathology Lung Pathology TUBERCULOSISTUBERCULOSIS
TUBERCULOSISTUBERCULOSISDefinition:Definition:Chronic infective granuloma caused by tubercle bacilliChronic infective granuloma caused by tubercle bacilli
Causative organism:Causative organism: Two types of bacilli infect man: Two types of bacilli infect man: Human and Bovine Human and Bovine Its growth is strict aerobic and inhibited by acidic phIts growth is strict aerobic and inhibited by acidic ph It has no known exotoxins, endotoxins or histolytic It has no known exotoxins, endotoxins or histolytic
enzymes enzymes It consists of complex lipid, carbohydrate around It consists of complex lipid, carbohydrate around
tuberculoprotein tuberculoprotein The bacteria is non-motile and are carried by The bacteria is non-motile and are carried by
macrophages to spread by various methods macrophages to spread by various methods
TUBERCULOSISTUBERCULOSISMethods of infectionMethods of infection:: Inhalation: Inhalation: is the commonest method is the commonest method
• The human bacilli are inhaled in coughed droplets or The human bacilli are inhaled in coughed droplets or dust contaminated with sputum from a case with opened dust contaminated with sputum from a case with opened TB TB
• The inhaled bacilli infect the tonsils or the lungThe inhaled bacilli infect the tonsils or the lung• Most infections are acquired by sustained exposure Most infections are acquired by sustained exposure
rather than casual contactrather than casual contact
Ingestion: Ingestion: of raw milk contaminated with bovine or human of raw milk contaminated with bovine or human bacilli. They infect the tonsils or intestinebacilli. They infect the tonsils or intestine
Skin inoculation: Skin inoculation: by handling infected material. This by handling infected material. This method is not commonmethod is not common
Microscopic Picture of TuberclesMicroscopic Picture of Tubercles
1-Epithelioid cells:1-Epithelioid cells:With abundant pale redWith abundant pale red
cytoplasm, indistinct cell borderscytoplasm, indistinct cell borders
and round or oval vesicular nucleiand round or oval vesicular nuclei
2- Langhan’s giant cells2- Langhan’s giant cells
3- Lymphocytes3- Lymphocytes
4- Central caseation4- Central caseation
TuberculosisTuberculosisClinical patternsClinical patterns
Primary typePrimary type: occurring in individuals following the : occurring in individuals following the initial infection, this type is called initial infection, this type is called childhood typechildhood type, as , as it is frequent in children leading to formation of it is frequent in children leading to formation of primary complexprimary complex
Post primary (secondary type)Post primary (secondary type):: tend to be more tend to be more chronic and slowly progressive. It is associated with chronic and slowly progressive. It is associated with significant (although inadequate) resistance significant (although inadequate) resistance
Primary TuberculosisPrimary Tuberculosis
Primary complexPrimary complex
Sites:Sites: TonsilTonsil
LungLung
IntestineIntestine
SkinSkin
Primary Pulmonary ComplexPrimary Pulmonary Complex
Ghon’s FocusGhon’s Focus
Under the pleura, Under the pleura,
small in size (1cm)small in size (1cm)
with late caseationwith late caseation
Tuberculous lymphangitisTuberculous lymphangitis
Tuberculous lymphadenitisTuberculous lymphadenitis
Fate of Primary ComplexFate of Primary ComplexI-I- HealingHealing
- Fibrosis & calcificationFibrosis & calcification
- Very small fociVery small foci
- Bacilli may persist for lifeBacilli may persist for life
II- Spread: low immunityII- Spread: low immunity
1- Direct:1- Direct: focus enlarges and gives new lesions with focus enlarges and gives new lesions with extensive caseationextensive caseation
2- Haematogenous2- Haematogenous Small No of bacilliSmall No of bacilli Moderate number of bacilliModerate number of bacilli Large number of bacilli Miliary TBLarge number of bacilli Miliary TB
3- Bronchial spread3- Bronchial spread
III- Encapsulation and reactivationIII- Encapsulation and reactivation
Secondary TuberculosisSecondary Tuberculosis This type of tuberculosis arises in a previously This type of tuberculosis arises in a previously
sensitized individual, whether the TB bacilli are sensitized individual, whether the TB bacilli are
derived from endogenous or exogenous sourcesderived from endogenous or exogenous sources
Most cases of secondary TB represent Most cases of secondary TB represent
reactivation of asymptomatic primary diseasereactivation of asymptomatic primary disease
The reactivation is the result of shift in the balance The reactivation is the result of shift in the balance
between host and organism due to such factors as between host and organism due to such factors as
reduced immunity, poor nutritional status, alcoholism or reduced immunity, poor nutritional status, alcoholism or
advanced ageadvanced age
Secondary Pulmonary TuberculosisSecondary Pulmonary Tuberculosis
Apical lesionApical lesion
Are almost always near the apex of Are almost always near the apex of
the lung at sites of high oxygen the lung at sites of high oxygen
tension (where the bacilli had tension (where the bacilli had
localized at the time of original localized at the time of original
bacillemia)bacillemia)
The minimal lesion at the apex The minimal lesion at the apex
consists of 1-3 cm focal area of consists of 1-3 cm focal area of
caseous consolidation, usually within caseous consolidation, usually within
1 -2cm from pleural surface1 -2cm from pleural surface
TB cavities with caseation
Secondary Pulmonary TuberculosisSecondary Pulmonary TuberculosisCourse of Apical lesionCourse of Apical lesion
aa) ) HealingHealing, scarring and calcification giving fibrocalcific , scarring and calcification giving fibrocalcific 'arrested‘ tuberculosis'arrested‘ tuberculosis
b) b) Progressive local spreadProgressive local spread: :
Fibrocaseous foci may undergo softening and erode through Fibrocaseous foci may undergo softening and erode through airways and emptying of this soft material into the bronchus airways and emptying of this soft material into the bronchus (open case) eaving a cavity lined by caseous material and (open case) eaving a cavity lined by caseous material and surrounded by fibrous tissue (Chronic fibrocaseous T.B)surrounded by fibrous tissue (Chronic fibrocaseous T.B)
Retrograde spread of caseous material through the distal Retrograde spread of caseous material through the distal airways produce small caseating (acinar lesions) mainly at airways produce small caseating (acinar lesions) mainly at the base of the ung. These lesions subsequently fuse into the base of the ung. These lesions subsequently fuse into larger lesionlarger lesion
Chronic firocaseous TB
The lung shows a rounded apical cavity (4x3cm.) having fibrous wall and yellow caseous lining. multiple yellow caseous foci Diagnosis:Chronic fibrocaseous pulmonary tuberculosis.
The lung shows a rounded apical cavity (8x7 cm.) having fibrous wall and yellow caseous lining. The lower lobe shows 2 small cavities and multiple yellow caseous foci The pleura shows fibrosis and adhesionsDiagnosis:Chronic fibrocaseous pulmonary tuberculosis.Pleural adhesions
The lung shows multiple scattered small yellow caseous foci.
Diagnosis:Miliary tuberculosis of the lung.
lung shows multiple scattered small yellow caseous foci. The lymph nodes are enlarged with yellow caseous foci. The pleura shows fibrosis and adhesions.
Diagnosis:Miliary tuberculosis of the lung. Pleural adhesions.
Parts of lumbar vertebrae. Two vertebral bodies and their disc are destroyed by yellow caseous material which collects under the anterior ligament (cold abscess).
There is a fracture between the two vertebrae.
Diagnosis:Pott’s disease.(tuberculosis of vertebrae)
Early TB in Lymph node
Section in a lymph node shows multiple tubercles formed of :1-Epithelioid cells having pale cytoplasm, round or oval vesicular nuclei and indistinct cell border
2- Langhan’s giant cells with large number of round nuclei arranged in the periphery as a circle or arch
3- Lymphocytes encircle the tubercle.
4- The center of the tunercle may show pinkish granular structureless areas of caseation.Diagnosis:Tuberculosis of lymph node
Langhan’s giant cells
Caseating TB lymph node
Caseating TB granuloma
Miliary TB lung
Section in lung tissue having mutiple small tubercles formed of epitheliid cells, Langhan’s giant cells and lymphocyte with minimal central caseation. The alvolar wall are congested.Diagnosis:Miliary tuberculosis, lung
Fibrocaseous TB lung
Section in the lung shows large irregular areas of caseation appearing granular or homogenous pink, surrounded by tuberculous reaction and fibrous tissue. Some alveoli show haemorrhagic exudate and others show compensatory emphysema.Diagnosis:Chronic fibrocaseous tuberculosis, lung.
Caseation
Fibrosis
Fibrocaseous TB lung