Affiliation:
1. From the Departments of Medicine and Dermatology, University of Alberta; the Capital Health Region Tuberculosis Clinic; and DynaLIFE Dx Laboratory Services, Edmonton, AB
Abstract
Background: The pathogenesis of lupus vulgaris, a form of cutaneous tuberculosis, is not always clear, especially in patients who do not have coexistent extracutaneous tuberculosis and in patients with single lesions. Objectives: To report a case of lupus vulgaris in a locus minoris resistentiae (a site of reduced resistance) and to use a unique set of clinical circumstances and laboratory tests to reconstruct the pathogenesis of the lesion and the response to treatment. Conclusion: Lupus vulgaris can occur in a locus minoris resistentiae; local trauma and possibly other factors, such as increased temperature, topical corticosteroids, and the virulence of the infecting strain, may facilitate the growth of Mycobacterium tuberculosis present at a locus minoris resistentiae as a result of a silent bacillemia.