Nerve abscess in Hansen’s disease as part of immune reconstitution inflammatory syndrome: a case report

Introduction

The practice of medicine has been profoundly changed by the HIV pandemic. In the present HIV era, atypical, unusual, or florid manifestations of a common disease should always warrant a search for underlying HIV infection.

Immune reconstitution inflammatory syndrome is an inflammatory reaction in HIV-infected patients after initiation of antiretroviral therapy, resulting from restored immunity to specific infectious or non-infectious antigens. ¹ The first case of leprosy presenting as immune reconstitution inflammatory syndrome was published in 2003. This is a case report of Hansen’s disease, borderline tuberculoid spectrum presenting with type 1 lepra reaction and nerve abscess formation, six months after initiation of highly active antiretroviral therapy.

Case report

A 36-year-old, HIV-positive male patient, tested positive by HIV spot and ELISA, with no other co-morbidities, on highly active antiretroviral therapy (HAART) (nevirapine, lamivudine, stavudine) since the past six months presented with tingling and numbness of left arm of one month duration. He had painful, red and raised lesions along the medial aspect of his left forearm. He also had a single, anaesthetic plaque over left elbow which he noticed one month ago.

Cutaneous examination revealed a well-defined to ill-defined 6 cm × 5 cm, hypopigmented-erythematous plaque over left elbow with marked impairment of sensation to temperature, fine touch and pain (Figure 1). Tender fluctuant swellings were seen along the ulnar nerve. A few of them had ruptured spontaneously discharging pus (Figure 2). There was a marked sensory deficit along the distribution of ulnar nerve of the arm and the medial aspect of hand but there was no impairment in motor function. He had no other patches anywhere else on the body. The left ulnar and radial cutaneous nerve were thickened and were tender on palpation. OPEN IN VIEWER

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Figure 2.

Fluctuant tender swelling and discharging sinus over medial aspect left forearm.

The CD4 count at time of initiation of antiretroviral therapy was 68 cells/mm³. At the time of presentation to the out patient department (OPD) six months later it was 199 cells/mm³. The viral load could not be measured due to lack of facilities.

Slit skin smear was negative. A skin biopsy from the plaque revealed caseating granulomas with palisading of the epitheloid cells, macrophages and plasma cells (Figure 3). Central caseation in epitheloid granulomas is unusual in Hansen’s disease. Granulomas with a caseating centre was documented in a previous case report of Hansen’s disease in type 1 lepra reaction presenting as IRIS. ² OPEN IN VIEWER

Based on the patient’s clinical features of nerve tenderness and histopathological findings, a diagnosis of Hansen’s disease, borderline tuberculoid spectrum in type 1 upgrading reaction with nerve abscess as a part of Immune Reconstitution Inflammatory Syndrome (IRIS) was made. Fine needle aspiration cytology (FNAC) of the nerve could not be done as the patient refused further invasive testing.

The patient was started on multidrug therapy for multibacillary leprosy (MB-MDT) as per WHO guidelines with continuation of HAART. He was also started on prednisolone 30 mg/day which was gradually tapered every two weeks. The nerve abscess subsided within two weeks of steroid therapy and did not require drainage.

Discussion

Immune reconstitution inflammatory syndrome (IRIS) is an acute symptomatic expression of a latent infection during the recovery of the immune system, usually as a response to antiretroviral therapy (HAART). This syndrome usually affects human immunodeficiency virus (HIV)-infected individuals at advanced stages of HIV disease (CD4 lymphocyte counts <200 cells/μl). ³

Ten per cent to 25% of patients who commence HAART experience IRIS, which is characterized by the presence of clinical manifestations of previously latent infection after improvement of the immune system resulting from antiretroviral therapy. Tuberculosis, herpes zoster, cytomegalovirus infection, Mycobacterium avium complex infection and hepatitis B and C have all been described as immune reconstitution processes. ⁴

In this patient, the reconstitution of immune functions after the initiation of HAART brought an intense inflammatory response against Mycobacterium leprae, which resulted in a type 1 upgrading reaction resulting in a nerve abscess. An unusual presentation of IRIS in an HIV-infected patient presenting as ulcerated plaques was reported from South India in 2013. ⁵ Several other cases^1,2,5–8 of immune reconstitution inflammatory syndrome presenting as Hansen’s disease in HIV-infected patients have been reported from India over the past several years.

In IRIS, the primary event is restoration of immunity by HAART, which then recognizes and mounts an immune response against the bacilli. In leprosy presenting as type 1 reaction in an HIV-infected patient, initially, there is lysis of bacilli by multidrug therapy which then induces the immune system and this reconstituted immune response leads to type 1 reaction. ² However , a reaction may occur even in the absence of multidrug therapy.

In patients co-infected with HIV and M. leprae, initiation of HAART has been associated with two IRIS phenomena: either unmasking of previously unrecognized leprosy or type 1 upgrading reactions with inflammation in pre-existing skin lesions. ⁹

A general case definition for IRIS was proposed by Robertson et al. in 2006. ¹⁰ The required criteria included worsening of symptoms of inflammation/infection, a temporal relationship between starting antiretroviral treatment and >1log10 decrease in plasma HIV load. The supportive criterion included increase in CD4+ cell count of > 25 cells/μl and biopsy demonstrating well-formed granulomatous inflammation. ¹¹

Our patient presented with symptoms of leprosy six months after initiation of HAART but the plasma viral load could not be measured. The CD4 count at time of initiation of HAART was 68 cells/mm³ and six months later it was 199 cells/mm³ and skin biopsy demonstrated well-formed granulomas.

Because access to HAART is increasing in countries where leprosy is endemic, the number of immune reconstitution inflammatory syndrome cases due to M. leprae will likely increase considerably in the near future. ¹² It is imperative to educate the patient on the necessity of continuing medication in such a scenario. Although there are several case reports of Hansen’s disease in association with IRIS, there hasn’t been many reports of nerve abscess formation.

There is an increasing awareness of Hansen’s disease presenting in type 1 reaction as a part of IRIS in HIV seropositive patients on HAART. A review of literature revealed only a few similar case reports^1,6–8,13 from India. Ours is a similar case report that can add to the literature.