<ul><li>Inflammation is a complex reaction in vascularized tissues. It is a protective response to injury, which dilutes, destroys, or isolates the causative agent. </li></ul>
Inflammation <ul><li>Inflammation is a reaction of the microcirculation characterized by movement of fluid and leukocytes from the blood into the extravascular tissues. This is frequently an expression of the host's attempt to localize and eliminate metabolically altered cells, foreign particles, microorganisms, or antigens. </li></ul>
<ul><li>Inflammation is classified according to duration: </li></ul><ul><li>acute inflammation, </li></ul><ul><li>chronic inflammation. </li></ul>
Inflammation <ul><li>Chronic inflammation may present in three histological forms: </li></ul><ul><li>granulomas </li></ul><ul><li>Chronic inflammation characterized by mononuclear cell infiltrations that may be diffuse or focal ; </li></ul><ul><li>production of connective tissue - fibrosis ; </li></ul><ul><li>formation of new blood vessels – angiogenesis . </li></ul><ul><li>These reaction patterns are often interrelated and may coexist. Infiltrates of chronic inflammation are composed of lymphocytes, plasma cells and macrophages in various proportions. </li></ul><ul><li>Persistent tissue damage is repaired continuously by fibroblasts and related connective tissue cells. </li></ul>
<ul><li>Inflammation has three major components (or stages): </li></ul><ul><li>Alteration of vascular caliber and structural changes in microvasculature. </li></ul><ul><li>Exudation, increased vascular permeability, emigration of leucocytes from microcirculation to the focus of injury. </li></ul><ul><li>Proliferation of connective tissue cells and cells of parenchyma to restore injury. </li></ul>
Classification of proliferative (chronic) inflammation. <ul><li>1. Interstitial inflammation . </li></ul><ul><li>2. Granulomatous inflammation . </li></ul><ul><li>3. Hypertrophic proliferative inflammation with formation of polyps & condylomas . </li></ul><ul><li>4. Proliferative inflammation around parasites . </li></ul>
Interstitial inflammation <ul><li>Lymphoid infiltration in the stroma ; </li></ul><ul><li>Diffuse; </li></ul><ul><li>Fibrosis and sclerosis . </li></ul>
Granulomatous inflammation <ul><li>Granulomatous inflammation is a distinctive morphologic pattern of inflammatory reaction encountered in relatively few diseases. Tuberculosis is the archetype of the granulomatous diseases, but also included are syphilis, sarcoidosis, cat-scratch fever, leprosy, brucellosis. </li></ul>
Granuloma <ul><li>A granuloma consists of a microscopic aggregation of plump fibroblasts or histiocytes that have been transformed into epithelial-like cells, designated there for epithelioid cells, surrounded by a collar of mononuclear leukocytes, principally lymphocytes and Occasionally plasma cells. Frequently, but not invariably, large giant cells are found in the periphery or sometimes in the center of granulomas. These giant cells may achieve diameters of 40 to 50 microns. </li></ul>
Granuloma <ul><li>Certain variation in the granulomatous pattern is encountered among the reactions of various etiologies. The granuloma of tuberculosis classically has central caseous necrosis. The fusion of many caseating granulomas may give rise to large macroscopic lesions of caseous necrosis. </li></ul>
This chest radiograph reveals a miliary pattern in all lung fields. Note the stippled appearance throughout.
Granulomatous inflammation <ul><li>Giant multinucleated cells comprise a large mass of cytoplasm containing numerous (20 or more) small nuclei. Two types of giant cells are encountered. The Pirogov-Langhans type is said to be characteristic of tuberculosis, but in reality it may be found in some of granulomatous reactions. The nuclei in this form tend to be arranged about the periphery of the cell, sometimes encircling the circumference, and at other times producing horse shoe patterns. The foreign body type giant cell differs in that the numerous nuclei are scattered throughout the cytoplasm in no distinctive pattern. </li></ul>
<ul><li>At high magnification, the granuloma demonstrates that the epithelioid macrophages are elongated with long, pale nuclei and pink cytoplasm. The macrophages organize into committees called giant cells. The typical giant cell for infectious granulomas is called a Langhans giant cell and has the nuclei lined up along one edge of the cell. The process of granulomatous inflammation takes place over months to years. </li></ul>
<ul><li>There is a small tan-yellow subpleural granuloma in the mid-lung field on the right. In the hilum is a small yellow tan granuloma in a hilar lymph node next to a bronchus. This is the "Ghon complex" that is the characteristic gross appearance with primary tuberculosis. In most persons, the granulomatous disease will not progress. Over time, the granulomas decrease in size and can calcify, leaving a focal calcified spot on a chest radiograph that suggests remote granulomatous disease. </li></ul>
Syphilitic mesaortitis Syphilis produces gummatous necrosis in the center of its granuloma. Gummatous necrosis tends to have a rubbery consistency, firmer than the soft cheesy texture of the tuberculous reaction.
Granulomatous inflammation. In contrast, sarcoidosis almost never produces central necrosis, and so the sarcoid granuloma is often called a "hard tubercule", while the tuberculosis granuloma is often referred to as a "soft tubercule". Epithelioid cells (ЭК) , lymphocytes (Л) , giant cells (ГК), asteroid bodies (АТ) . Zone of fibrosis (ЗФ) .
<ul><li>A fungus ball composed of blue-staining hyphal elements of Aspergillus is seen here in a bronchus. Fungus balls may also form when fungi colonize cavitary lesions of tuberculosis. </li></ul>
<ul><li>Branching, septate hyphae are close-packed here and radiating outward in this aspergilloma. </li></ul>
<ul><li>The hyphae of Aspergillus are seen more clearly here. Aspergillus has a propensity to invade into blood vessels. </li></ul>
Fungal Infections Coccidioidomycosis Coccidioidomycosis, which is caused by inhalation of the spores of Coccidioides immitis, is widely spread through the southwestern part of the United States, sharing many of the clinical and pathologic features of histoplasmosis and tuberculosis.
<ul><li>This well-formed granuloma has a large Langhans giant cell in the center. Two small spherules of Coccidioides immitis are seen in the giant cell. </li></ul>
Fungal Infections Coccidioidomycosis In most instances, the lesions are limited to a peripheral parenchymal granuloma, with or without lymph node granulomas. In a few instances, however, the lesion is progressive, although the rate of progression is slow. Immunocompromised patients may experience rapid progression of the disease.
<ul><li>At higher magnification, the thick wall of the C. immitis spherule is seen in a giant cell in the center of the photomicrograph. The spherule contains endospores. In the United States, C. immitis is endemic to the southwest. </li></ul>