Tuberculosis Verrucosa Cutis on a Burn Scar : A Case Report

<p>Tuberculosis verrucosa is warty plaque-like form of cutaneous tuberculosis resulting from the invasion of Mycobacterium tuberculosis into theskin in a previously M. tuberculosis-sensitized person. Cutaneous tuberculosis is classied into four subtypes by infection pattern : direct inoculation, direct inltration from internal lesion, hematogenous dissemination and tuberculid. We report a case of tuberculosis verrucosa that developed on a burn scar. A 67-year-old man presented with nodules and reddish plaqueon a burn scar on theright forearm. Hewas burned by a hot asphalt mixturesix years prior and treated the wound without medical intervention, but pruritic nodules developed on the burn scar later. He visited his previous doctor and received a topical steroid, which provided limited relief of pruritus, and he was referred to our hospital one year later. On physical examination, a 12×16 cm-sized reddish plaque on the right forearm with nodules arranged in a horseshoe shape was observed on the margin of the lesion. Skin biopsies were performed from the nodules, and the histopathological ndings were consistent with epithelioid cell granuloma without caseation necrosis. M. tuberculosis complex was detected in the mycobacterium culture of the biopsy specimen. As there was no tuberculous lesion other than the skin based on whole-body examination, we diagnosed him with tuberculosis verrucosa cutis caused by direct inoculation of M. tuberculosis. We started combination therapy with anti-tuberculosis drugs and the lesion was cured six months later. There have been 38 reported cases of tuberculosis verrucosa cutis in Japan in the past 35 years, and only 2 cases exhibited caseous necrosis histopathologically. This suggests that tuberculosis cannot be excluded by the absence of caseous necrosis in a biopsy specimen. Tuberculosis verrucosa cutis should be considered as a differential diagnosis of intractable warty lesions and we should perform mycobacterium culture in addition to pathological tissue examination. Skin Research, 18 : 216-221, 2019 </p>