Recurrent nodules in the calves: a sign of tuberculosis <br><b>Abstract in English</b>

Abstract

AIMS: To describe a case of erythema induratum of Bazin, classified as a tuberculid, or skin lesion with similar histological features to true cutaneous tuberculosis, in which the relation with Mycobacterium tuberculosis cannot be easily demonstrated. CASE DESCRIPTION: A 60-year-old woman presented with recurrent multiple nodules in the legs. Skin examination revealed violaceous painless nodules, some of them ulcerated, with a serous fluid, located on both legs in an asymmetric way, predominantly in the calves. Lesions disappeared spontaneously for brief periods. Skin biopsies revealed septal and lobular panniculitis with epithelioid granulomata and vascular necrosis. Tuberculin skin test was positive. Culture of the cutaneous lesions and polymerase chain reaction to Mycobacterium tuberculosis were negative, but mediastinal lymph nodes collected through mediastinoscopy were cultivated and positive to Mycobacterium tuberculosis. Therapy with isoniazid, rifampicin, pyrazinamide and ethambutol were administered. After two months under therapy the skin lesions healed. The clinical and histopathological features and the strong positive tuberculin skin test have strongly suggested the diagnosis of erythema induratum of Bazin. Positive culture for Mycobacterium tuberculosis and the remission of the lesions with antituberculosis therapy confirmed the diagnosis. CONCLUSIONS: Clinicians must be aware of the differential diagnosis of recurrent skin lesions, including the erythema induratum of Bazin. In this case, association with tuberculosis was confirmed by positive culture of mediastinal lymph nodes for Mycobacterium tuberculosis and remission of the lesions with antituberculosis therapy