CHRONIC INFLAMMATION
Dr. Saleem Shaikh
Introduction
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Chronic inflammation is defined as prolonged process in which
tissue destruction and inflammation occur at the same time.
Chronic inflammation can be caused in three ways
 Following acute inflammation – the cause persists or survives for
a long time
 Recurrent attacks of acute inflammation – reccurent infection of
the gall bladder may lead to chronic cholecystitis
 Chronic inflammation starting de novo
General features of chronic inflammation Mononuclear cell infiltration: lymphocytes and monocytes
Tissue destruction and necrosis
Proliferative changes
Types of Chronic Inflammation
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Based on etiology –
Non Specific – the irritant (causative) agent is non specific and
results in formation of granulation tissue and fibrosis. Eg:
osteomyelitis, chronic ulcer
Specific - the irritant agent causes a specific histologic response
eg: tuberculosis
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Based on histologic features
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Chronic non-specific inflammation
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Chronic granulomatous inflammation
Granulomatous Inflammation
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Granuloma is defined as a circumscribed, tiny lesion composed of
macrophages and lymphoid cells
The formation of granuloma is a protective defense reaction by the
host but eventually causes tissue destruction because of persistence
of the poorly digestible antigen.
Composition of a granuloma:
 Epitheloid cells: resemble epithelial cells appearance; these are
modified macrophages, which are a little elongated.
 Multi nucleated giant cells: these are formed by fusion of
epitheloid cells and may have more than 20 nuclei. Based on the
arrangement of nuclei the giant cells can be grouped into various
types
 Lymphoid cells:
 Necrosis: seen in some forms of granulomas
 Fibrosis:
Types of Giant cells
Tuberculosis
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Mycobacterium tuberculosis causes tuberculosis.
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Also known as Koch’s bacillus
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This was once a very common and fatal disease but with advance in
medicine and research the incidence and prevelance of tuberculosis
had been reduced drastically. Resurgence of this disease is being
seen because of AIDS.
Mode of transmission:
 Inhalation
 Ingestion
 Inoculation
 Transplacental routes
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Spread of tuberculosis:
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Local spread – macrophages carry the bacilli to surrounding tissues
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Lymphatic spread –
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Hematogenous spread –
Lung is the main organ to be affected by tuberculosis – pulmonary
tuberculosis
Two main types
Primary
Secondary
Primary tuberculosis
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The infection of a person who has not been previously infected or
immunised is called as primary tuberculosis or Ghon’s complex.
the primary complex or ghon’s complexx in lung consists of three
components Pulmonary component – ghon’s focus is a lesion in the lung. It is
1-2 cm in size and is seen usually in the periphery of upper part
of the lower lobe.
The lesion is made up of granulomas with caseation necrosis
 Lymphatic vessel component – the lymphatic vessels contain
macrophages containing the bacilli
 Lymph node component – the affected lymph nodes are matted
and show casseation necrosis.
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Fate of primary tuberculosis –
 Heal by fibrosis and may undergo calcification
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The caseous material may disseminate to other parts of the same
lung. – progress primary tuberculosis
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The bacillus may enter into blood vessels and spread to various
tissues and organs - Primary milliary tuberculosis
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The healed lesion may get reactivated due to decrease in
immunity – progressive secondary tuberculosis.
Secondary tuberculosis
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Infection in a person who has been previously infected or sensitized
is called as secondary infection
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Endogenous source
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Exogenous source
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The main lesion of secondary tuberculosis is seen in the apical
region of the lung.
Microscopically it also has tuberculus granulomas with caseation
necrosis.
Leprosy
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Also known as Hansen’s disease is a chronic infectious disease,
mainly affecting the cooler parts of the body such as skin, mouth,
respiratory tract etc.
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Caused by mycobacterium leprae
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Two main types - Lepromatous leprosy & Tuberculoid leprosy
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The patient has patches on the skin, which are hypopigmented and
may have erythema. The lesions are hypoaesthtic or anaesthetic.
Syphilis
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Syphilis is a sexually transmitted disease caused by spirocheates –
Treponema pallidum.
Types of syphilis – Acquired & Congenital
Acuired –
 Primary syphilis – typical lesion is known as Chancre, this appears
2-3 weeks after infection.
 Secondary syphilis – mucocutaneous patches 2-3 months after
infection
 Tertiary syphilis – gumma appears 2-3 years later. These gummas
are granulomas.
Congenital- develops in a foetus due to infection in mother. Many
characteristic features seen like Hutchinsons triad and Hutchinsons
teeth.