Giant Lupus Vulgaris with Negative T-SPOT.TB, a Case Report and Literature Review.

Lupus vulgaris is a paucibacillary form of cutaneous tuberculosis (CTB) which is accounting for 1-2% of all tuberculosis cases. Here, we report a rare huge lupus vulgaris misdiagnosed as sarcoidosis for 11 years. A 65-year-old man presented to dermatology outpatient with a large asymptomatic erythematous plaque and erosions on his neck. Sarcoidosis was initially diagnosed on the basis of negative interferon-gamma release tests and biopsies of lymph nodes and lesions. The patient was treated with long-term oral steroid and immunosuppressive agents, but the lesions expanded gradually. Lupus vulgaris was finally diagnosed by combining molecular detection and mycobacterial culture. The skin lesions were resolved after six months of standard antituberculosis therapy. We report this case to analyze the reasons for the misdiagnosis and review-related literature to further provide experience for the diagnosis and treatment of cutaneous tuberculosis with negative T-SPOT.TB.