Tuberculosis Of Skin
- Cutaneous tuberculosis (TB) is essentially an invasion of the skin by Mycobacterium tuberculosis, the same bacteria that cause TB of the lungs (pulmonary TB).
- Cutaneous TB is a relatively uncommon form of extrapulmonary TB (TB infection of other organs and tissues).
- Even in countries such as India and China where TB still commonly occurs, cutaneous outbreaks are rare (<0.1%)
Types of cutaneous TB
|Types of cutaneous TB||Features|
|TB verrucosa cutis/ Anatomist’s warts/ Prosector’s warts/ Verruca necrogenica||
- The diagnosis is usually made or confirmed by characteristic histopathological features on skin biopsy.
- Typical tubercles are caseating epithelioid granulomas that contain acid-fast bacilli. These are detected by tissue staining, culture and polymerase chain reaction (PCR).
Other tests that may be necessary include:
- Tuberculin skin test (Mantoux or PPD test)
- Interferon gamma release assay blood test
- Sputum culture (it may take a month or longer for results to be reported)
- Chest X-ray and other radiological tests for extrapulmonary infection.
- Interferon gamma release assays (IGRA)
- Farmer with a single warty lesion on leg may be suggestive of Tuberculosis verrucosa cutis
- Tuberculides are seen in Lichen scrofulososum
- Lichen scrofulosorum is an extending eruption of small follicular papules characterized by involvement of the sweat glands and hair follicles by causing non caseating epitheloid granulomas in young persons with underlying TB.
- Anatomist’s warts/ Prosector’s warts/ Verruca necrogenica are the synonyms of tuberculosis verrucosa cutis
- In miliary TB the granulomas are of size 1-2 mm
- Cryptic type miliary TB usually affects elderly patients
- Choroid tubercles is the pathognomonic finding in miliary TB
- The commonest focus of Scrofuloderma is Lymph node
- Lupus vulgaris is characterized by caseation necrosis
- Miliary TB & Tuberculosis verrucosa cutis is a form of Post-primary TB infection
- Lupus vulgari is the Most common type of cutaneous T.B.
- Apple Jelly nodule at root of nose is the characteristic finding of Lupus vulgaris
- Gradually progressive plaque on a buttock with of 15 cm in diameter, annular in shape, with crusting and induration at the periphery and scarring at the center is suggestive of lupus vulgaris
- Miliary Tuberculosis occur following primary infection and secondary reactivation
- Sputum microscopy is usually negative & Montoux test is negative in 20-30% in Miliary Tuberculosis
- Systemic miliary TB occurs when spread occurs via Arterial
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