[Association of borderline tuberculoid leprosy and tuberculosis: A case report and review of the literature].

INTRODUCTION: In metropolitan France, nearly 20 new cases of leprosy are diagnosed each year. The incidence of tuberculosis in France is 8/100,000 inhabitants and there are very few accounts of association of these two mycobacteria. Herein we report a case of co-infection with borderline tuberculoid (BT) leprosy and disseminated tuberculosis diagnosed in metropolitan France.

PATIENTS AND METHODS: A male subject presented with diffuse painless infiltrated erythematous plaques. The biopsy revealed perisudoral and perineural lymphohistiocytic epithelioid cell granuloma as well as acid-alcohol-fast bacilli on Ziehl staining. PCR was positive for Mycobacterium leprae, confirming the diagnosis of leprosy in the BT form. The staging examination revealed predominantly lymphocytic left pleural effusion, right-central necrotic adenopathy without histological granuloma, negative screening for BK, a positive QuantiFERON-TB™ test, and a positive intradermal tuberculin reaction. The clinical and radiological results militated in favour of disseminated tuberculosis. Combined therapy (rifampicin, isoniazid, ethambutol and pyrazinamide) together with clofazimine resulted in regression of both cutaneous and extra-cutaneous lesions. This rare co-infection combines leprosy, often present for several years, and tuberculosis (usually pulmonary) of subsequent onset. The pathophysiological hypothesis is that of cross-immunity (with anti-TB immunity protecting against subsequent leprosy and vice versa), supported by the inverse correlation of the two levels of prevalence and by the protection afforded by tuberculosis vaccination. In most cases, treatment for TB and leprosy improves both diseases. Patients presenting leprosy should be screened for latent tuberculosis in order to avoid reactivation, particularly in cases where corticosteroid treatment is being given.