Erythema induratum of Bazin induced by tuberculin skin test

Abstract

We report a case of a 50-year-old man with a 15-year history of recurrent flares of painful and ulcerated nodules located on the trunk and limbs. Spontaneous resolution resulted in hyperpigmented scars. The patient acknowledged tuberculosis contact in the past, without development of the disease or antituberculous treatment. Skin biopsy confirmed the diagnosis of EIB. Ziehl–Neelsen staining, mycobacterial culture, and detection of MTB DNA by PCR from skin biopsy were all negative. Tuberculin skin test (TST) was strongly positive (28 mm) with vesiculation (Fig. 1a). Similarly, an interferon-gamma releasing assay, the Quantiferon-TB Gold test, was positive at 9.28 UI/ml. One month later, the patient developed new painful nodules surrounding the TST area (Fig. 1b). A skin biopsy showed similar findings to that performed before (Fig. 2). Ziehl–Neelsen staining and detection of MTB DNA by PCR were both negative. His diagnosis was EIB secondary to TST. Tuberculosis involvement of internal organs was ruled out by complementary tests. Antituberculous chemotherapy was initiated without adverse effects and resolution of cutaneous lesions.