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Infectious diseaseChapter 15 1 Introduction Although the features of pathologic change of infectious diseases is different, its basic pathological changes is the same, belong to the inflammation. u Acute: Fibrinousbacillary dysentery; Suppurativesuppurative meningitisu Chronic: Granulomatous inflammation TB, leprosy2 Tuberculosis(一一) Outline 1. Concept: TB is a chronic granulomatous disease caused by tubercle bacilli The lung is its prime target, but any organ may be infected. The characteristic lesion : Formation of tubercle Central caseous necrosis. 2. Classification Pulmonary TB primary TB secondary TB Extrapulmonary TB intestinal TB tuberculous meningitis tuberculous peritonitis TB of bone , joint TB of LN TB of urinary S genital S二二. Etiology and Pathogenesis1. The pathogenic organism Mycobacterium TB G+ Tubercle bacillus(1) Type: M. hominid M. bovine Mouse, fish typehave no virulence in host(2) Routes of infection Respiratory tract: main direct person to person transmission of sneeze, cough droplets with organisms (1-20 bacteria/droplet) Alimentary tract: less; contaminated milk by bovine type Local skin lesion: rare2. Pathogenic substance of mycobacterium tuberculosis Lipid: Related to pathogenicity, especially glycolipid cord factor: wax D: cause severe allergy tissue damage Protect bacillary bodies from digestion of macrophage inhibit bacteria combine with lysosome, the bacteria can survive Phosphatide change the macrophage into epithelioid cells in the inflammatory focus Polysaccharide lipoarabinomannan inhibit activity of macrophage secreting TNF-: necrosis IL-10: inhibit cell immune(Dentric Cells) Complement: Promoting phagocytosis Protein:Heat-shock protein Ag autoinmmune reaction3. Pathogenesis Cell immunity Type hypersensitivity三三. Basic pathological changes of TBreactivity quantityvirulencefeatures of tissue 1. Exudation(1) Conditions early stage immunityquantity virulence severe hypersensitivity(2) Pathologic changes serous or serofibrinous early :neutrophils late :macrophages(3) Site lung, serosa, synovialis, meninges(4) Result absorbed completely development proliferation necrosis 2. Proliferation characteristic lesiontubercle(1) Conditions quantity virulence strong immune reaction(2) Pathologic changes formation of tubercle possesses certain diagnostic feature Gross the size of a millet clear edge grayish , semitransparent yellow with necrosis, somewhat rise on the surface of organ. LM: typical lesiontubercle ( formation based on cell immune ) Center: caseous necrosis Surrounding epithelioid cell Langhans giant cell Outside lymphocyte fibroblast Epithelioid cellu Source: macrophage phagocytizeM.tuberculosisuShape: large, abundant cytoplasm, pseudopoduFunction: phagocytize, kill mycobacteriumLanghans giant celluSource fusion of epithelioid cells division of nuclei without cytoplastic divisionuShape: multinuclei, floral hoop or horseshoe-likeuFunction: phagocytizing and killing mycobacterium3. Necrosis(1) Conditions: quantity virulenceresistence severe allergy(2) Lesion: featurecaseous necrosis Gross: slight yellow, homogenous exquisite creamy LM: red staining, no structure, granular substance(3) Result uneasily absorbed not autolysis, excluded sometimes: softed, liquefyspread Three lesions can exist simultaneously transform one another四四. Transformation of basic lesion1. Healing or repair(1) Absorption and disappearing Main healing way of exudation through lymphatics Small necrosis, proliferation (2)Fibrosis, fibrous encapsulation and calcification healing way of necrosis proliferation Fibrosis: tubercle, exudation, small necrosisorganization Fibrous encapsulation: large necrotic focusCalcification: large focus dry,concentration Calcium precipitation calcification2. Deterioration (1) Focus extension appear exudation and necrosis around focus (2) Dissolution and spread liquefied necrosis exclude through natural tracts (branchi, urinary tract and so on) cavity necrosis spread branchi, urinary tract lymphatics blood stream一一. Primary pulmonary TB The first infection with tubercle bacillus children and infants An infection of persons who have not had prior contact with the tubercle bacillus teenage, adult(一一) Features of lesionPrimary complex(Ghon complex) Primary focus Lymphangiitis TB of hilar lymph nodes. 1. Primary focus usually single, round, 1-1.5cm areaGross: gray-yellow, consolidationCommon site: lower segment of the upper lobe or the upper segment of the lower lobe, close to the pleuraLesion: caseous necrosis2. Lymphangiitis can not be seen, X-raystrip-like tubercle bacillidrained to lymphatics3. TB of hilar lymph nodes lymphonodus enlarge, caseous necrosis4. X-ray: dumbbell-like shadow5. Symptoms: slight, no obvious signs(二二) Development and result1. Natural healing: most patient(98%) small focus: absorption, fibrosis large focus: fibrous encapsulation or calcification2. Deterioration and spread via various routes(1) ReasonIn children: malnutrition or with influenza, measles In adult: with suppressed or defective immunity (2) Routes of spread Spread via lymphatics TB of hilar lymph nodes: u Other LN tracheobronchial LN mediastinal LN Spread via bronchi : less u Hypoplasia of childrencan be spread easilyu Small diameter of bronchiblocked easily lesion: primary focuserode bronchidischarge its contentsbronchibronchopneumonia Spread via bloodstream:tubercle bacilli enter bloodstreamhematogenous spreadmiliary TB of organs (lung, meninges, liver, spleen, kidney, adrenal glands)二二. Secondary pulmonary TB(一一) Outline usually results from reactivation of dormant, endogenous tubercle bacilli in a sensitized patient who has had previous contact with the tubercle bacillus. 1. Reinfectionuusually adultsadult type pulmonary TBuinitiated from apex of lung secondary focus 2. Pathogenesis Exogenous reinfection not related to primary infection Endogenous reinfection PP TB spread via bloodstream Primary bronchial Extrapulmonary TBbloodlung(二二) Features of lesion Distinguish between primary pulmonary TB secondary pulmonary TB Primary SecondaryInfection Primary SecondaryPatients Children Adult Immune or None Establishedhypersensitivity Characteristics Primary complex VariableInitial focus Lower part of upper lobe Apex of the lung upper part of lower lobe close to the pleuraFeatures Exudation and necrosis Proliferation and necrosisDissemination Lymphatic or hematogenous BronchialClinical course Short,spontaneous healing Long, instable (三三) Pathological change and types1.Focal pulmonary TB initial lesion of secondary pulmonary TB(1) Lesionu usually below apex 2-4cm , 0.5-1cm in size , clear edgeu proliferation main (2) Resultsu Healing in most cases: fibrosis, calcificationu Progressinfiltrative pulmonary TB2. Infiltrative pulmonary TB most common type of active pulmonary TB(1) Arising in:u progress of focal pulmonary TBu few cases occur initially (2) Lesionu sitebelow clavicle, unclear edgeu center: smaller caseous necrosisu surrounding: surrounded by inflammation exudative serous fluid, monocytes, LC, neutrophils(3) Clinical features Symptoms: low-grade fever, anorexia , fatigue, weight loss, night sweats , general malaise cough . Tubercle bacilli (+) (4) Results Healing: treatment earlierabsorption, fibrosis, encapsulation, calcification Progress Caseous necrosis liquefiedbronchialcaseous pneumoniadestroy pleuraspontaneous pneumothoraxthoracic cavitytuberculous pyopneumothoraxpersistentchronic fibro-cavitative pulmonary TB3. Chronic fibro-cavitative pulmonary TB adult, common type(1) Arising in: usually acute cavity of infiltrative pulmonary TB Formation of thick wall cavity one or more bilateral lung upper lobe of lung variation in size irregular shapeCavity wall (LM) : three layers inner: caseous necrosis midial: tuberculous granulation tissue outer: fibrous tissue Unilateral or bilateral lung: new or old, variation in size, different types of lesion Adjacent tissue widely fibrosis pleura thickened cirrohtic pulmonary TB4. Caseous pneumonia(1) Arising in:uimmunity, allergyuinfiltrative type pulmonary TBubacteria in acute or chronic cavity, disseminated by bronchi(2) Lesions lobular lobar Gross: enlargement of lobe, consolidation ,acute cavity LM: alveoli filled with serofibrous exudates, many macrophages, widely caseous necrosis (3) Clinical features bad prognosisdeathgalloping consumption5. Tuberculoma(1) Arising in:uInfiltrative P.TB large necrotic focus F. encapsulationuFusion of several focus (2) Lesions solitary, fibrous encapsulated, clear edge, round, caseous necrosis focus diameter: 2-5cm number: usually one, sometime multiple site: upper lobeprimary PTBsecondary PTBExtrapulmonary TB 1. Acute systemic miliary TBprimary focuseroding vein of lungleft heartall the organs (lung, liver, brain, spleen, kidney)miliary TBv(1) Gross: scattered uniformly , similar size resemblance to millet , yellow-white with clear edge(2) LM: u main :proliferative lesion tubercleu exudation or necrosis(3) Clinical course: u obvious symptoms treatment in time well prognosisu lesstuberculous meningitisdeath 2. Chronic systemic miliary TB: common in adultexudation + proliferation + necrosislesionuneven3. Acute pulmonary miliary TBua part of acute systemic miliary TB: commonulimited in lung: lessCaseous necrosis of tracheo-bronchial and mediastinal, hilar LN vein corner right heartlungacute miliary tuberculosisGross: cut surface dark-red in color, numerous grey or grey-yellow miliary nodules in size rising on surface of lung四四. Extrapulmonary TBLN tuberculosis: spread via lymphaticsAlimentary tuberculosis: swallow sputum or food with bacteriaTB of skin: infection by injury to skinTB of other organs: mainly from spread via bloodstreamincubative focusdevelopment(一一) Intestinal TB1. Primary intestinal TB(1) Less, usually children, drink the milk contaminated by M. bovis.(2) Lesionprimary complex: primary tuberculous ulcer tuberculous lymphangiitis TB of mesenteric LN 2. Secondary intestinal TB(1)Secondary to active cavitative PTB resulting from the swallowing of infected sputum (2) Lesion anywhere in intestine common:ileum cecum region(85%) Ulcerative type Proliferative type urich-lymph tissuespread by lymphaticsufood stayed at the ileum or cecum for a long timeimprove opportunity of touching bacteriaumechanic injury: due to strongly peristalsis and reversed peristalsisUlcerative type:. Gross: band-like ulcer, whose long axis run transversely, vertical with long axis of intestine. LM surface: caseous necrosis below: tuberculous granulation tissue. ComplicationStenosis of intestinal lumin scarconstrict, commonAdhesion with adjacent tissuePerforation Hemorrhage Proliferative type: less Features: uformation of tuberculous granulation tissueufibrous tissue proliferationintestinal wall thicken, cavity stenosisobstruction(二二) Tuberculous meningitis1. Origin: infants: caused by primary pulmonary TB spread by bloodstream adults: TB of lung, bone, joint, urinary, genital sspread via bloodstream Partly caused by rupture of tuberculoma in brain 2. Features Site: the base of the brain, in the subarachnoid space Lesion: uexudation: inflammatory cell, serousunecrosis utubercle: rare 3. Results:nblood vesselsobliterative endoarteritisinfarct of brainnarachnoid fibrosishydrocephalus 4. Symptoms: headache, malaise, mental confusion, vomit and so on(三三) Tuberculosis of urinary and genital system1. TB of kidney 20-40y most common(1) Origin: primary pulmonary spread by bloodstream(2) Features: Cheesy foci (kidney) Ureter TBhydrops of pelvis bladderTB(3) Symptoms: hematuria, pyuria, frequent micturition, precipitant urination2. TB of male genital system Showing close relationship with TB of urinary S kidneyureterprostate gland seminal vesicles, epididymis3. TB of female genital system Spread by bloodstream or lymphatics or directly infection TB of fallopian tubes: the most common (四四) TB of bone and joints1. Result from bacteria spread via bloodstream usually children2. TB of bone(1) Site: vertebrae(especially T10-L2) most common the ends of long bones(2) Lesion Caseous necrotic type: necrosis, sequestrum Liquefy cold abscess TB of vertebrae necrosis deformity destroy discus Proliferative type: less tuberculous granulation T fibrosis encapsulate no obvious necrosis and sequestrum3. TB of the joints Secondary to TB of bone Site: hip, knee, elbow, ankle Lesionusynovial membrane tuberculous granulation Tucavity of jointserous fibrinous-exudation (五五) TB of LNcervicalmost common
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