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