Tuberculosis Colliquativa — A form of cutaneous tuberculosis that develops when Mycobacterium tuberculosis spreads directly from an underlying infected structure.
Aetiology
- Caused by Mycobacterium tuberculosis
- Usually arises from contiguous spread of TB infection from:
- Cervical lymph nodes (most common)
- Bone (osteomyelitis)
- Joints
- Subcutaneous tissue
- More common in malnutrition and immunosuppression
Pathophysiology
- Primary TB infection occurs elsewhere (often lungs or lymph nodes).
- Bacilli spread to subcutaneous tissue.
- Formation of granulomas → caseous necrosis → cold abscess.
- Abscess breaks through the skin, forming ulcers and sinuses.
Clinical presentation
- Early stage: Firm, painless subcutaneous nodules
- Progression:
- Nodules soften → cold abscess
- Overlying skin becomes thin and violaceous
- Ruptures leading to ulcers with irregular edges, containing caseous material
- Characteristic findings:
- Multiple ulcers connected by sinus tracts/fistulas
- Healing leaves retractile, puckered scars
- Common locations:
- Cervical region of the neck (most frequent)
- Supraclavicular area
- Axilla
- Chest wall
- Inguinal region
Investigations
Combination of clinical evaluation + laboratory tests:
- Mantoux test/IGRA usually positive
- Skin biopsy (gold standard) → granulomatous inflammation with Langhans giant cells and caseous necrosis
- Ziehl–Neelsen stain (AFB stain) may show acid-fast bacilli
- Culture or PCR for TB → confirmatory
- Chest X-ray to assess pulmonary involvement
Management
Standard Anti-Tuberculosis Therapy (ATT):
6-month regimen:
- Intensive phase (2 months): HRZE
(Isoniazid + Rifampicin + Pyrazinamide + Ethambutol)
- Continuation phase (4 months): HR
(Isoniazid + Rifampicin)
Supportive treatment:
- Wound care and hygiene
- Drainage/excision for large abscesses if needed
- Nutritional support
- Evaluate for systemic TB
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