Direct inoculation of Mycobacterium tuberculosis into the skin of a previously sensitized individual results in tuberculosis verrucosa cutis.
Clinical features:
(1) The lesion occurs in a person previously exposed to tuberculosis, so the tuberculin skin test is often positive.
(2) The lesion develops at a site of direct inoculation of Mycobacterium tuberculosis into the skin.
(3) A warty skin lesion develops that is initially an indurated nodule but it progresses to an irregular, reddish-brown plaque with central scarring.
Often the exposure is occupation-related, with lesions on the fingers or hands:
(1) healthcare workers
(2) mortician
(3) butcher
(4) veterinarian surgeon
A biopsy of the skin or lymph node will show granulomatous inflammation, often with few acid fast bacilli (paucibacillary).
A culture of the lesion or molecular marker is needed to confirm the presence of Mycobacterium tuberculosis. Other mycobacteria can cause similar lesions.
Misdiagnosis may occur if acid fast bacilli are not seen and microbiological studies are not performed.
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