Complications of Tuberculosis — MD Exam Answer (15 Marks)

Introduction

A. PULMONARY COMPLICATIONS

1. Hemoptysis

• Minor hemoptysis: Rupture of blood vessels within areas of lung parenchymal destruction — very common in active disease.
• Massive hemoptysis (≥600 mL/24 h): Life-threatening. Mechanisms include:
  • Rasmussen aneurysm: Erosion of a tuberculous cavity into a pulmonary artery → pseudoaneurysm formation → potentially fatal bleeding
  • Aspergilloma superinfection of a healed TB cavity (see below)
  • Tumor development in scarred lung eroding bronchial/pulmonary vessels

2. Pneumothorax

• Rupture of a tuberculous cavity into the pleural space
• Rupture of a subpleural bleb
• Formation of bronchopleural fistula

CXR: Cavitary TB with left-sided pneumothorax secondary to bronchopleural fistula (Rosen's Emergency Medicine)

3. Pleural Effusion (Tuberculous Pleuritis)

• Occurs early after primary infection or late in post-primary cavitary disease
• Often self-limiting but 65% relapse rate if untreated; active TB develops within 5 years
• Fluid characteristics: Exudate, protein >50% serum protein, WBC 500–2500 cells/mL (lymphocyte predominant), low glucose; AFB smear rarely positive, cultures positive in only 25–30%
• Late complication: empyema necessitans — empyema eroding through chest wall forming sinus tract

4. Empyema

• Extensive parenchymal disease and cavitation → cavity ruptures into pleural space
• More common late in the disease; often catastrophic; associated with bronchopleural fistula
• Untreated: spontaneous pleuro-cutaneous fistula, chest wall mass, rib and vertebral destruction

5. Airway Tuberculosis (Endobronchial TB)

• Bronchiectasis: Most common complication of endobronchial TB
• Bronchial stenosis: From endobronchial TB or direct extension from tuberculous adenitis
  • Radiographic appearances: persistent segmental/lobar collapse, lobar hyperinflation, obstructive pneumonia
• Laryngeal TB: Highly infectious; proximal extension of lower airway disease; patients almost always have active pulmonary TB

6. Superinfection with Fungi (Aspergilloma)

• Healed TB leaves open cavities and areas of bronchiectasis prone to colonization
• Aspergilloma (fungus ball): Aspergillus fumigatus most common; ball of fungal mycelium within cavity, shows the "air crescent sign" on CXR/CT
• Clinical significance: can cause massive fatal hemoptysis

CXR: Aspergilloma (fungus ball) in a right upper lobe TB cavity (Rosen's Emergency Medicine)

7. Respiratory Failure / Cor Pulmonale

• Extensive bilateral disease → progressive destruction of lung parenchyma → restrictive and obstructive defects → hypoxia → pulmonary hypertension → cor pulmonale → right heart failure
• ARDS may develop in fulminant miliary TB

B. EXTRAPULMONARY COMPLICATIONS

8. Miliary (Disseminated) Tuberculosis

• Haematogenous dissemination → seeding of multiple organs simultaneously
• Classic CXR: 1–3 mm discrete "millet seed" opacities uniformly distributed bilaterally
• Mortality ~21% (high due to delayed treatment)
• Fulminant form: ARDS + DIC
• Treatment must be initiated on clinical suspicion — do not await confirmation

Miliary pattern on CXR and CT (Rosen's Emergency Medicine / Am Fam Physician 2005)

9. Tuberculous Meningitis (CNS TB)

• Vasculitis → aneurysm, thrombosis, haemorrhagic infarction
• Basal ganglia vessel involvement → lacunar infarcts, movement disorders
• Middle cerebral artery → hemiplegia

• Diplopia from basilar exudate in up to 70%
• SIADH → hyponatremia (common)
• CSF: lymphocytic pleocytosis (0–1500 WBC/mL), elevated protein, low glucose
• Classic CT/MRI triad: basal meningeal enhancement + hydrocephalus + cerebral/brainstem infarction
• Tuberculomas may be seen as round parenchymal lesions

10. Tuberculous Pericarditis

• From direct extension of infection from tracheobronchial tree, mediastinal/hilar lymph nodes, sternum, or spine; or haematogenous seeding in miliary TB
• Leading cause of pericarditis in HIV-infected patients in the US

• Pericardial effusion → cardiac tamponade
• Constrictive pericarditis (most feared) → fibrous obliteration of pericardial space → impaired diastolic filling → right heart failure
• Myocarditis
• Aortic regurgitation (rare)

11. Lymphadenitis (Scrofula)

• Most common form of extrapulmonary TB
• Most commonly in young women and children
• Site: anterior/posterior cervical chain or supraclavicular fossa
• Stages: discrete rubbery nodes → matted → fluctuant → collar-stud abscess → sinus tract
• Diagnosis: fine-needle aspiration (sensitivity 77%, specificity 93%)
• Complication: permanent sinus formation if incision and drainage performed

12. Skeletal TB (Pott's Disease)

• Spinal TB (Pott's disease): 50–70% of skeletal TB; usually thoracic/lumbar vertebrae
• Hip/knee: 15–20%; other joints: 15–20%
• Pathogenesis: reactivation of dormant lesions seeded during primary bacteraemia; or contiguous spread from paravertebral nodes

• Back pain/stiffness; kyphosis (gibbus deformity)
• Paraspinal cold abscess in >50% → sinus tract formation
• Skip lesions (abscess tracking up/down spine sparing vertebral bodies)
• Main complication: spinal cord compression → paraplegia (Pott's paraplegia)
• Intervertebral disc space narrowing on imaging (loss of disc height) — hallmark finding

13. Genitourinary TB

• Haematogenous seeding → granulomas, scarring, obstruction anywhere in urinary tract
• Classic finding: sterile pyuria (pyuria in acidic urine with no organisms on culture)
• Urinalysis: pyuria, hematuria, albuminuria

• Nephrolithiasis
• Ureteral obstruction or reflux
• Recurrent bacterial UTIs
• Hypertension
• Papillary necrosis
• Renal insufficiency
• Autonephrectomy (complete calcification and destruction of kidney — "putty kidney")
• Rare: transitional cell carcinoma in scarred tissue
• Males: tuberculous epididymo-orchitis (commonest form of male genital TB)

14. Gastrointestinal and Peritoneal TB

• Most common site: ileocaecal region (owing to abundance of lymphoid tissue and slow transit)
• Features: pain, anorexia, diarrhea, obstruction, hemorrhage, palpable mass
• Can mimic: appendicitis, Crohn's disease, carcinoma, acute abdomen
• Anal TB: fissures, fistulae, perirectal abscesses

• From local spread (lymph node/intestinal focus/infected fallopian tube) or miliary seeding
• Features: abdominal pain, distension, fever, anorexia, weight loss
• Ascites: exudative, 500–2000 cells/mL, lymphocyte predominant; AFB smear low yield
• Can mimic alcoholic hepatitis or cirrhosis with ascites
• Peritoneal biopsy often required for diagnosis

15. Other Extrapulmonary Sites

C. COMPLICATIONS RELATED TO IMMUNE RESPONSE

Immune Reconstitution Inflammatory Syndrome (IRIS)

• Occurs in HIV-positive patients starting antiretroviral therapy while on TB treatment
• Paradoxical worsening of TB symptoms despite adequate treatment
• Due to restored immune response attacking residual mycobacterial antigens

D. COMPLICATIONS RELATED TO TREATMENT

Summary Classification Table