Background: Lupus vulgaris (LV) is a rare, paucibacillary form of post-primary cutaneous tuberculosis, accounting for 1.5% of all extrapulmonary tuberculosis cases globally. LV may arise via hematogenous spread, lymphatic route, or contiguous dissemination. The present case highlights the importance of considering LV in patients with chronic and atypical skin lesions, particularly in tuberculosis-endemic areas. Case Illustration: A 17-year-old female presented with a 2-month history of a solitary, tender, erythematous nodule on the left arm. Initially suspected as a skin tumor, the lesion was surgically removed and tested for biopsy. One month postoperative, a new lesion developed precisely at the same site, prompting referral to the dermatology department. Histopathological examination revealed Langhans-type giant cells, confirming lupus vulgaris. After six months of antituberculosis drug therapy for extrapulmonary tuberculosis, significant clinical improvement was observed, with the lesion evolving into a hyperpigmented macule, and the apple jelly sign was absent. Discussion: Diagnosis of LV must be confirmed by histopathology or culture, which may be followed by additional tests to support the diagnosis, including the tuberculin test, acid-fast bacilli test, or polymerase chain reaction test. Histopathological examination is considered a cost-effective, practical diagnostic modality compared with other examinations in resource-limited settings. Conclusion: LV can mimic other granulomatous conditions, making diagnosis challenging, especially when physicians are unfamiliar with it. Chronic and atypical skin lesions should raise suspicion for LV and warrant histopathological evaluation, particularly in tuberculosis-endemic areas.
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