A 37-year-old man with no significant past medical history
presented with a 3-year history of a rash on his right hand that started after he punched someone in the mouth during a fight. The patient denied any pain, pruritus, discharge or constitutional symptoms. He also denied any occupational
exposure, recent travel, or history of immunosuppression
or tuberculosis (TB). On physical examination, the patient had a 6-cm × 4-cm, well-demarcated, verrucous, vegetative
plaque (Figure 1). There was no fluctuance, discharge, or sporotrichoid spread. A TB skin test (TST) was positive. Skin biopsy and culture studies were also performed. Histopathology
demonstrated hyperkeratosis, acanthosis, and a mixed lichenoid
infiltrate consisting of lymphocytes and plasma cells; granulomas were inconspicuous (Figure 2). Bacterial, fungal, and acid-fast bacilli (AFB) stains were negative. Mycobacterium tuberculosis was identified by high-performance liquid chromatography
Cutaneous TB has a variety of clinical presentations (Table 1).1 Lesions may be secondary to direct inoculation of M tuberculosis
from an exogenous source, spread from an endogenous source, or appear as tuberculids. Tuberculosis verrucosa cutis
(TVC) occurs after direct inoculation of TB into the skin in someone who has been previously infected with mycobacteria.
2As seen in our case, the inoculation of mycobacteria is typically at sites of trauma. Historically, physicians have been prone to acquiring TVC, also known as warty TB, from patient
contact or cadavers.3 Although it generally occurs on the hands, it can affect children in tropical climates, who contract the bacteria by walking barefoot. A typical lesion presents as an asymptomatic, indurated papule that enlarges into a firm, annular, reddish-brown plaque. Fissures discharging pus may extend into the underlying base. Without treatment, the lesion slowly extends over many years but eventually undergoes spontaneous involution and usually results in an atrophic scar.4 The diagnosis of TVC is confirmed with a skin biopsy and positive cultures for AFB.5 Given that affected patients have a high level of immunity, interferon-γ release assays and TSTs are typically positive.
Treatment for cutaneous TB is the same as for systemic TB, commonly consisting of a 4-drug regimen.6 Our patient was