Impact of Mycobacterium leprae and Mycobacterium lepromatosis on immune reactions and clinical outcomes in Hansen's disease: A single-center retrospective analysis

Abstract

To the Editor: Patients with leprosy or Hansen's disease (HD) may develop severe immunologic reactions including reversal reaction (RR), erythema nodosum leprosum (ENL), and Lucio's phenomenon (LP). LP, the least common but potentially most severe reaction, is a necrotizing vasculopathy associated with significant morbidity/mortality risk. 1 Frade M.A.C. Coltro P.S. Filho F.B. et al. Lucio's phenomenon: a systematic literature review of definition, clinical features, histopathogenesis and management. Indian J Dermatol Venereol Leprol. 2022; 88: 464-477 Crossref PubMed Scopus (1) Google Scholar Previously, Mycobacterium leprae was thought to be the sole pathogen responsible for HD and all immunologic reactions. However, a novel pathogen, Mycobacterium lepromatosis, was found to cause HD mainly in Mexico and Central/South America. 2 Han X.Y. Seo Y.H. Sizer K.C. et al. A new Mycobacterium species causing diffuse lepromatous leprosy. Am J Clin Pathol. 2008; 130: 856-864 Crossref PubMed Scopus (173) Google Scholar Given the adverse sequelae associated with RR, ENL, and LP, 1 Frade M.A.C. Coltro P.S. Filho F.B. et al. Lucio's phenomenon: a systematic literature review of definition, clinical features, histopathogenesis and management. Indian J Dermatol Venereol Leprol. 2022; 88: 464-477 Crossref PubMed Scopus (1) Google Scholar there is a critical need to investigate the association between M. lepromatosis and these reactions. This study sought to compare the prevalence of immunologic reactions and clinical outcomes in HD caused by M. leprae and M. lepromatosis.