Not the usual suspect: a case of erythema induration of Bazin in an urban primary care clinic

Frontline clinicians in the United States, especially those working in safety net hospitals or with immigrant populations, will likely see cutaneous tuberculosis given the tremendous burden of tuberculosis infection worldwide. The tuberculid is a subtype of cutaneous tuberculosis that poses a diagnostic challenge because organisms are not found in smears or cultures taken from the lesions. Tuberculid lesions can mimic erythema nodosum, thrombophlebitis, and cellulitis. We describe the case of a 57-year-old woman immigrant from China who presented with tender, subcutaneous nodules on her ankle and thigh in the setting of prior exposure to tuberculosis. We describe the clinical, pathophysiologic, and histopathologic features of tuberculids in order to raise awareness among primary care clinicians about this difficult to diagnose but readily treatable manifestation of tuberculosis.