Cutaneous Tuberculosis

• 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). 

Types of cutaneous TB:

• Several different types of cutaneous TB exist.
• Direct infection of the skin or mucous membranes from an outside source of mycobacteria results in an initial lesion called the tuberculous chancre.
• The chancres are firm shallow ulcers with a granular base.
• They appear about 2-4 weeks after mycobacteria enter through broken skin.
• The immune response of the patient and the virulence of the mycobacteria determine the type and severity of cutaneous TB.

Investigation:

• 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).

Treatment for Cutaneous Tuberculosis:

1. Patients with pulmonary or extrapulmonary TB disease need to be treated with antitubercular drugs.
2. This usually involves a combination of antibiotics (isoniazid, rifampicin, pyrazinamide and ethambutol) given over a period of several months and sometimes years.
3. Occasionally surgical excision of localized cutaneous TB is recommended.
4. According to a journal published in 2009 on Dermatology, Cutaneous Tuberculosis (CTB) treatment is the same as that for systemic TB and consists of long, multidrug therapy.

Recommendations:

• Although the incidence of CTB is rare, it should be considered in patients presenting with atypical skin lesions suggestive of an underlying infectious etiology.
• It is imperative that physicians have a high index of suspicion in order to quickly and effectively diagnose and treat these substantially morbid skin conditions.
• Prompt consideration leads to a swift diagnosis and proper treatment resulting in high patient satisfaction

References:

http://dermnetnz.org/pathology/tuberculosis-path.html

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2923933/

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4230662/