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Chapter 26 : Cutaneous Tuberculosis
Category: Clinical Microbiology; Bacterial Pathogenesis
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Cutaneous tuberculosis (TB) is not a well-defined entity but comprises a wide spectrum of clinical manifestations. Primary inoculation TB results from the entry of mycobacteria into the skin or, less frequently, the mucosa of a person who has not previously been infected or who has no natural or artificial immunity to Mycobacterium tuberculosis. The pathogenesis of cutaneous TB from an exogenous source is similar to that of other primary diseases. Lupus vulgaris is a particular type of chronic cutaneous TB in a previously sensitized person with a high degree of TB sensitivity. The histopathological picture of lupus vulgaris is diverse and not always diagnostic. TB of the breast-tuberculosis mastitis-is difficult to recognize and frequently misdiagnosed as breast cancer. Breast involvement is a result of retrograde lymphatic extensions from underlying mediastinal, parasternal, axillary, or cervical lymph nodes. Tuberculids are a group of cutaneous conditions occurring in the presence of TB but containing no stainable or culturable acid- fast bacilli (AFB); based on histopathology, then, they were previously regarded as an allergic reaction to the infection. Monoclonal antibody assays and the PCR technique have become increasingly useful clinically. Treatment of lupus vulgaris with isoniazid alone has resulted in high cure rates. Combination chemotherapy is recommended for patients with extracutaneous disease and multiple skin lesions and for those with profound immunosuppression.
Key Concept Ranking
- Enzyme-Linked Immunosorbent Assay
Paronychia in a pathology resident after performing an autopsy on a patient with unsuspected TB. Reprinted with permission from Archives of Dermatology ( 22 ).
Draining ulcerative lesion over dorsum of the left hand associated with tuberculous osteomyelitis of the fourth and fifth metacarpals. Reprinted with permission from Medicine ( 6 ).
Shallow (10-cm) draining ulcer extending from the anorectal line in a patient with external pulmonary TB. Reprinted with permission from Medicine ( 6 ).
Typical lesion of lupus vulgaris on a patient whose skin biopsy specimen grew Mycobacterium tuberculosis.
Classification of cutaneous TB and synonymous terms used previously a