CHRONIC INFLAMMATION Dr. Saleem Shaikh

Introduction 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 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 Based on histologic features Chronic non-specific inflammation Chronic granulomatous inflammation

Granulomatous Inflammation 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 Mycobacterium tuberculosis causes tuberculosis. Also known as Koch’s bacillus 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

Spread of tuberculosis: Local spread – macrophages carry the bacilli to surrounding tissues Lymphatic spread – Hematogenous spread – Lung is the main organ to be affected by tuberculosis – pulmonary tuberculosis Two main types Primary Secondary

Primary tuberculosis 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.

Fate of primary tuberculosis – Heal by fibrosis and may undergo calcification The caseous material may disseminate to other parts of the same lung. – progress primary tuberculosis The bacillus may enter into blood vessels and spread to various tissues and organs - Primary milliary tuberculosis The healed lesion may get reactivated due to decrease in immunity – progressive secondary tuberculosis.

Secondary tuberculosis Infection in a person who has been previously infected or sensitized is called as secondary infection Endogenous source Exogenous source 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 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. Caused by mycobacterium leprae Two main types - Lepromatous leprosy & Tuberculoid leprosy The patient has patches on the skin, which are hypopigmented and may have erythema. The lesions are hypoaesthtic or anaesthetic.

Syphilis 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.