Concomitant Tuberculous and Lepromatous Lymphadenitis: Clues and Pitfalls of Leprosy Concealed by Tuberculosis in Lymph Nodes

Comorbidities between tuberculosis and leprosy are expected in endemic regions. Pulmonary tuberculosis and cutaneous leprosy are the most prevalent coinfections. One of the common manifestations of tuberculosis is generalized lymphadenopathy. In contrast, leprosy is clinically less suspected to manifest as a generalized lymphadenopathy, and it is pathologically unusual to diagnose leprosy primarily in lymph nodes. Concomitant tuberculous and lepromatous lymphadenitis are unprecedented and clinically unexpected, particularly in nonendemic countries. This imposes diagnostic challenges. We report concurrent tuberculosis and leprosy that were diagnosed in a lymph node in 45-year-old man with generalized lymphadenopathy. The effaced lymph node was predominantly replaced by caseating epithelioid granulomas alternating with foamy histiocytes. Ziehl-Neelsen stain showed positive acid-fast bacilli in the necrotizing granulomas only. The initial differential diagnosis of the nodal foamy macrophages included fungal infections, leishmaniasis, and Whipple disease, for which the special stains were negative. The vacuolated macrophages were disregarded as nonspecific lipogranuloma. A modified acid-fast stain was not considered. The histopathologic clues to nodal lepromatous leprosy included the presence of intracytoplasmic globi, intermixed microabscesses, and lymphoplasmacytic infiltrate and involved pericapsular nerves. Wade-Fite stain was subsequently performed. It revealed numerous lepra bacilli within the foamy histiocytes. The final diagnosis was concurrent disseminated tuberculosis and leprosy. Nodal lepromatous leprosy could be missed when compounded by concurrent nodal tuberculosis, particularly in developed countries. The clinicians and pathologists should have a high index of suspicion, particularly in patients from or with history of travel from endemic regions. Certain histopathologic features are helpful clues to avoid pitfalls.