TUBERCULOSIS
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● a/k/a KOCH’s disease
● acid fastness – due to MYCOLIC ACID
● Virulence factor — “CORD factor”
a) PRIMARY TUBERCULOSIS
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●Most commonly seen in children
● a/w unsensitised and unexposed individuals
●source of organism— exogenous
● most commonly starts as “LATENT DISEASE”
● unilateral hilar lymph enlargement
■ GHON’S FOCUS:-
● Subpleural fibrocaseous lesion (CONSOLIDATION) of lung parenchyma.
● microscopically contains epitheloid granulomatous inflammation
■GHON’S COMPLEX:-
●Consists of Subpleural ghon’s focus and involved lymph nodes.
●Ghon’s complex found below clavicle.
■RANKE’S COMPLEX :-
● Ghon’s focus alongwith FIBROSIS and CALCIFICATION known as RANKE’S COMPLEX.
●Calcification
●Pleural effusion
●Erythema nodosum
● Phlyctenular conjunctivitis
b) POST-PRIMARY
(=SECONDARY)PULMONARY TUBERCULOSIS
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● Seen in previously sensitized host due to reactivation of latent primary lesions
● frequently a/w decreased immune status
■PUHL’S LESION:-
● Lesion in lung apex.
● No lymph node involvement
■ SIMON FOCUS
● it is a tuberculous (TB) nodule formed in lung apex.
● Due to spread of primary TB infection from elsewhere in the body to lung apex via bloodstream.
● Simon focus nodules are often calcified.
■ ASSMAN FOCUS:-
●infraclavicular lesion of chronic pulmonary T.B.
● Lymph node involvement is RARE.
secondary TB more likely to cavitate than primary TB.
●Endobronchial spread along nearby airways is relatively common finding, resulting in relatively well-defined 2-4 mm nodules or branching lesions TREE-IN-BUD APPEARANCE on CT scan.
#tuberculoma formation and miliary TB are also recognised patterns of secondary TB.
c) MILIARY PULMONARY TUBERCULOSIS
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●Miliary tuberculosis is uncommon but carries a poor prognosis.
● It represents haematogeneous dissemination of an uncontrolled tuberculous infection.
● seen both in primary and post-primary tuberculosis.
● lungs are usually the easiest location to image.
● Miliary deposits appear as 1-3 mm diameter nodules.
■ RICH FOCUS :-
● It is a tuberculous granuloma occurring on brain cortex that ruptures into subarachnoid space, causing tuberculous meningitis.
■WEIGERT’S FOCUS :-
● Subintimal foci in pulmonary vein. ( d/t metastatic caseous TB.)
■ SIMMOND’S FOCUS:-
● Localized tb foci in liver.
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CONGENITAL TUBERCULOSIS:-
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● Infection with tubercle bacilli either during intrauterine life or before complete passage through birth canal is termed as congenital tuberculosis.
● Three possible modes of infection of fetus:-
- Hematogenous infection via umbilical vein
- fetal aspiration of infected amniotic fluid
- fetal ingestion of infected amniotic fluid
● Most common “site” and most common "site of primary complex " both is — LIVER ( primary complex in liver is suggestive of congenital TB)
● Prognosis is poor.
● Revised criteria for diagnosis of congenital tuberculosis ( by Cantwell ) :-
● Proven tuberculosis lesions in the infant plus one of the following:-
i. Lesions occurring in the first week of life.
ii. A primary hepatic complex
iii. Maternal genital tract or placental tuberculosis, and
iv. Exclusion of postnatal transmission by thorough investigation of contacts.