Lupus Vulgaris Mimicking Tinea Corporis

Lupus vulgaris (LV) is the most encountered form of cutaneous tuberculosis 1 .A 49-year-old man presented with a 7-year history of asymptomatic well-demarcated violaceous colored plaque over the left buttock (Fig. 1A).He had been treated with various antifungal agents under the diagnosis of tinea corporis and none of these treatments was effective.A punch biopsy specimen revealed an unspecified inflammation (Fig. 2A).Laboratory tests and chest X-ray were normal and interferon-gamma release assay (IGRA) test was negative.Polymerase chain reaction for Mycobacterium tuberculosis (MTB PCR) and non-tuberculosis mycobacteria were both negative.Potassium hydroxide preparation exam and periodic acid-Schiff stain also showed negative results.Accordingly, oral treatment with acitretin 20 mg/day and topical steroid was administered; however, there was no improvement (Fig. 1B).Therefore, a biopsy was performed again with a larger excised tissue and the result showed granulomatous inflammation (Fig. 2B).Acid-fast bacilli were found (Fig. 2C).Mantoux test and MTB PCR were positive.There was no history of tuberculosis.Based on these results, a diagnosis of LV was confirmed.The patient was treated with four anti-TB drugs and the skin lesions were almost regressed (Fig. 1C).The most pronounced histopathological feature of LV is the formation of typical nodules; however, other secondary changes could be superimposed 1 .Diagnosing LV only by clinical and histological result can be difficult; therefore, other