Histology and Explanation of Chronic Inflamation

Chronic inflammation is a long lasting inflammation (weeks or months) due to persistent aggressive stimuli and is characterized by: active inflammation with mononuclear cells, tissue destruction and repair. It can follow acute inflammation or can be chronic right from the beginning.

Types of chronic inflammation : unspecific (e.g. : chronic peptic ulcer) and specific (granulomatous).

According to the mechanism, granulomatous inflammation may be: immune type (tuberculosis, sarcoidosis) and non-immune type (foreign body reaction).

Classification of granulomatous inflammation, according to the etiology :

1. Infectious granuloma :
   • Bacterial :
     • Mycobacterium tuberculosis (Koch bacillus) - Tuberculosis
     • Mycobacterium leprae - Leprosy
     • Treponema pallidum - Syphilis
     • Gram-positive bacillus (Actinomyces israeli) - Actinomycosis
     • Gram-negative bacillus (Bartonella henselae) - Cat-scratch disease
   • Parasitic :
     • Toxoplasma gondii - Toxoplasmosis
     • Helminths - Cysticercosis
   • Fungi (Candida albicans) - Candidiasis
2. Foreign body granuloma
3. Unknown etiology granuloma :
   • Sarcoidosis
   • Crohn's disease

Examples:

1. Tuberculus Lymphadenitis (Tuberculous Granuloma)
2. Pulmonary Tuberculosis
3. Foreign Body Granuloma
4. Sarcoidosis