Acute necrotizing lepromatous lymphadenitis: an erythema-nodosum-leprosum-like reaction in lymph nodes

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.

Case Report: Lepromatous Leprosy Masquerading as Acute Suppurative Lymphadenitis

Leprosy is a chronic cutaneous infection. It is usually characterized by thickened nerves and maculo-anesthetic patches. Leprosy often has an unusual presentation, which is a diagnostic challenge. In this case report, we present a case of an elderly male who presented with fever and chronic pus-draining axillary, cervical, and inguinal lymph nodes. He also had a weak left foot for the previous 5 months. During his hospital stay, he developed additional papular lesions over his extremities. We performed fine needle aspiration from the lymph nodes and skin biopsy, which were suggestive of lepromatous leprosy. We initiated him on antileprosy medication. On follow-up, he was responsive to therapy. Although skin and nerve involvement in leprosy is common, this case had an atypical presentation of discharging lymph nodes.

Host-Related Laboratory Parameters for Leprosy Reactions

Leprosy reactions are acute inflammatory episodes that complicate the course of a Mycobacterium leprae infection and are the major cause of leprosy-associated pathology. Two types of leprosy reactions with relatively distinct pathogenesis and clinical features can occur: type 1 reaction, also known as reversal reaction, and type 2 reaction, also known as erythema nodosum leprosum. These acute nerve-destructive immune exacerbations often cause irreversible disabilities and deformities, especially when diagnosis is delayed. However, there is no diagnostic test to detect or predict leprosy reactions before the onset of clinical symptoms. Identification of biomarkers for leprosy reactions, which impede the development of symptoms or correlate with early-onset, will allow precise diagnosis and timely interventions to greatly improve the patients' quality of life. Here, we review the progress of research aimed at identifying biomarkers for leprosy reactions, including its correlation with not only immunity but also genetics, transcripts, and metabolites, providing an understanding of the immune dysfunction and inflammation that underly the pathogenesis of leprosy reactions. Nevertheless, no biomarkers that can reliably predict the subsequent occurrence of leprosy reactions from non-reactional patients and distinguish type I reaction from type II have yet been found.

Ocular leprosy

Ocular involvement in leprosy is estimated to be 70-75%, about 10-50% of leprosy patients suffer from severe ocular symptoms, and blindness occurs in about 5% of patients. The disease leads to many ophthalmologic symptoms and signs in the range of the eyeball itself, as well as of the bulb adnexa, ie, eyebrows, eyelids with eyelashes, and lacrimal drainage system. Especially dangerous are complications of lagophthalmos and corneal hypoanesthesia, neurotrophic or infectious keratitis, and iridocyclitis and cataract formation, which may lead to significant decrease of visual acuity or even blindness. Multidrug treatment rapidly interrupts transmission of Mycobacterium leprae by infectious patients, but even after being completed, it does not guarantee the withholding of ocular complications.

Mycobacterium tuberculosis infection is associated with the development of erythema nodosum and nodular vasculitis

Background

Mycobacterium tuberculosis (MTB) infection has been suggested to contribute to the pathogenesis of erythema nodosum (EN) and nodular vasculitis (NV), the classic forms of panniculitis. However, there is little evidence to demonstrate the presence of MTB in the skin lesions. This study is aimed at evaluating the association between MTB infection and the development of EN and NV in a Chinese population.

Methods

A total of 107 patients (36 EN, 27 NV, and 44 others) with vasculitis and 40 control cases with other skin diseases were recruited and their skin lesion samples were subjected to real time polymerase chain reaction (PCR) analysis of the IS6110 and mpt64 gene fragments of MTB. Their blood mononuclear cells were tested for MTB antigen-specific IFN-γ responses by QuantiFERON®-TB Gold In-Tube (IT) assays.

Results

PCR analysis revealed that 7/23 (30.4%) and 7/18 (38.9%) of the EN and NV samples were positive for the IS6110 DNA, respectively, which were significantly higher than 3/34 (8.8%) of other vasculitis (OV) and 3/40 (7.5%) of the control samples (p<0.05). The nested Real-Time PCR assay indicated that 6/7 (86%) of the IS6110-positive EN samples, all of the IS6110-positive NV and control samples, but only 1/3 of the IS6110-positive OV samples, were positive for the mpt64 gene. Similarly, 19/32 (59.4%) of the EN patients, 20/26 (76.9%) of the NV patients, and 17/36 (47.2%) of the OV patients were positive for MTB antigen-specific IFN-γ responses, which were significantly higher than 6/40 (15%) of the controls (p<0.05).

Conclusion

Our data strongly suggest that MTB infection and active TB are associated with the development of NV and EN in Chinese.

Immune responses in mice with murine leprosy

Mice infected with Mycobacterium lepraemurium showed marked histological changes in the thymus and lymph nodes. In the thymus there was a progressive depletion of lymphoid cells and replacement by macrophages, many of which contained bacilli in the advanced stages of the disease. In lymph nodes there was depletion of paracortical immunoblasts and accumulation of macrophages. Infected mice showed impaired cell-mediated immune responses, including delayed rejection of skin grafts and depression or absence of contact sensitivity. Humoral immune responses to bovine serum albumin and sheep erythrocytes in infected mice were normal. The defect in cell-mediated immune responses is thought to be secondary to the massive infection, and is discussed in relation to impaired immune responses in human lepromatous leprosy.