Pulmonary Tuberculosis

INTRODUCTION:
  • Pulmonary Tuberculosis (TB) is an infectious disease that mainly affect the lungs parenchyma.
  • TB is a contagious bacterial (M. tuberculosis) infection that mainly affects the lungs parenchyma, but may spread to other organs.
  • It is a Chronic specific Inflammatory infectious Disease caused byMycobacterium TuberculosisIn human.
  • Usually attacks the lungs but It can also effect any part of The body.
ETIOLOGY:
  • TB is caused by the bacteria M. tuberculosis (most common cause).
  • Other than tuberculosis – includes;
  1. M. avium intracellulare
  2. M. kansasi
  3. M. scrofulaceuru
  4. M. ulcerans
  5. M. marinum and etc.
  • It also caused by breathing in air droplets from a cough or sneeze of an infected person this is called Primary TB.
MANIFESTATIONS-symptoms: The primary stage of TB usually doesn’t cause symptoms. When symptoms of TB occur, they may includes;
Fatigue
Fever
Unintentional weight loss
Breathing difficulty
Chest pain
Wheezing.
MANIFESTATIONS- signs:
  • Cough up of mucus and blood
  • Excessive sweating at night.
FINDINGS:
  • Hematological:
  1. Mild anemia
  2. Leukocytosis
  3. Thrombocytosis
  4. ↑ ESR
  • Histopathology:
  1. Microscopically, the characteristic lesion in tuberculosis is the tuberculous granuloma
  2. Epithelioid macrophages and Langhans giant cells along with lymphocytes, plasma cells, maybe a few PMN's, fibroblasts with collagen, and characteristic caseous necrosis in the center Epitheloid cells appear to have enhanced abilities to secrete lysozyme and a variety of enzymes but decreased phagocytosis potential.
  • CT Chest:
  1. Bilateral upper lobe fibrosis 
  2. Mediastinal enlarged necrotic nodes with peripheral rim enhancement
PRIMARY TUBERCULOSIS:
  • Initial infection of TB bacilli in young children
  • Middle and lower lobes of lungs are most commonly involved
  • Ghon focus - subpleural focus in lower lobe and lower part of upper lobe
  • Ghon focus is accompanied by transient hilar or paratracheal lymphadenopathy
  • Some patients develop erythema nodosum on the legs or phlyctenuiar conjunctivitis
  • Primary/Ghon complex - Ghon focus + enlarged hilar lymph nodes +/- pleural thickening
  • Primary complex occurs 3-8 weeks after initial infection
  • After 2-6 months heals spontaneouslyby fibrosis leaving a calcified 
  • Shows Consolidation & pulmonary fibrosis
  • Calcified healed lesions and hilar lymph nodes are called Ranke complex
  • Pleural effusion is seen in two-thirds of cases
  • In severe cases, the primary site rapidly enlarges, its central portion undergoes necrosis, and shows Fibrocasseous lesion
  • Tuberculin test becomes positive
  • Primary TB is not associated with high-level transmissibility
SECONDARY TUBERCULOSIS:
  • Also called adult type, reactivation or secondary tuberculosis
  • Results from endogenous reactivation of latent infection
  • Definition of relapse in TB is A pateint who returns sputum positive which was cured by previous treatment
  • Usually localized to the apical and posterior segments of the upper lobes of lungs, where the substantially higher mean oxygen tension (compared with that in the tower zones) favors mycobacterial growth
  • Necrosis and tissue destruction leads to cavitation
  • Liquefied necrotic contents are discharged into the airways and undergo bronchogenic spread, resulting in satellite lesions within the lungs that may in turn undergo cavitation Some pulmonary lesions become fibrotic and later calcify
  • Lymph node involvement unusual
  • Massive hemoptysis due to erosion of a blood vessel in the wall of a cavity or from rupture of a dilated vessel in a cavity (Rasmussen's aneurysm) or from aspergilloma 
  • formation in an old cavity
  • Up to one-third of untreated patients reportedly succumb to severe pulmonary TB within a few months after onset (galloping consumption)
Exam Question
  • The most common hematologic finding associated with pulmonary tuberculosis is Mild anemia, leukocytosis,thrombocytosis with slightly elevated ESR
  • Reactivation tuberculosis is almost exclusively a disease of the lungs
  • Epitheloid cells in tuberculosis act as Secretory cells
  • Pleural effusion is seen in two-thirds of cases of primary pulmonary tuberculosis
  • Fibrocasseous lesion is seen in primary pulmonary tuberculosis
  • Phlyctenular conjunctivitis is seen in primary pulmonary tuberculosis
  • Primary pulmonary tuberculosis Shows Consolidation & pulmonary fibrosis
  • Primary Tuberculosis most commonly involves Lungs
  • Most commonly involved organ in congenital tuberculosis is lung
  • A man presents with fever, wt loss and cough; Mantoux reads an induration of 17 x 19 mm: Sputum cytology is negative for AFB shows pulmonary tuberculosis infection 
  • Secondary pulmonary tuberculosis usually involves Apex of lungs
  • Ghon's focus is seen in primary pulmonary tuberculosis
  • Paratracheal lymphadenopathy is seen in primary pulmonary tuberculosis
  • Primary pulmonary tuberculosis Heal spontaneously by fibrosis
  • Reactivation of pulmonary tuberculosis always occur at Apex of the upper lobe
  • Cavitation of the lungs is a feature of secondary pulmonary tuberculosis
  • Bilateral upper lobe fibrosis & Mediastinal enlarged necrotic nodes with peripheral rim enhancement in chest CT is suggestive of tuberculosis
  • Definition of relapse in TB is A pateint who returns sputum positive which was cured by previous treatment

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