BI28: Immune reconstitution syndrome following discontinuation of long-term azathioprine for ulcerative colitis

M. Hunjan,¹ P. Boesch² and I. Verpetinske³

¹Solihull Hospital, University Hospitals Birmingham NHS Trust, Birmingham, UK; ²College of Medicine and Dentistry, University of Birmingham, Birmingham, UK; and ³Corbett Hospital, Dudley Group of Hospitals NHS Trust, Dudley, UK

We report the case of a 46 year-old-man who presented to our clinic with a 5-month history of an intensely itchy, red rash affecting his trunk and limbs. There were no predisposing factors to the rash and there was no clear history of any infections or new medications. He was otherwise systemically well. His past medical history included ulcerative colitis for which he has been on long-term treatment with azathioprine, but this had been stopped a few months before the eruption appeared. On examination, there was a widespread erythematous maculopapular eruption sparing the palms, soles and genital area. Some lesions looked folliculitic in nature and there was evidence of postinflammatory hyperpigmentation. Blood tests showed a raised white cell count of 17·3 × 10⁹ cells L^–1, eosinophils of 5·23 × 10⁹ L^–1 and a C-reactive protein of 25 mg L^–1. Further lymphocyte studies showed a raised CD4 count and CD4/CD8 ratio. Syphilis, HIV, hepatitis B and hepatitis C serology were negative, and vasculitic screen and immunoglobulins, including IgE, were normal. Computed tomography of the thorax, abdomen and pelvis was also normal, ruling out a paraneoplastic phenomenon. Skin biopsy showed a suppurative folliculitis with fungal spores consistent with a fungal aetiology, possibly Malassezia spp., with scanty eosinophils of unknown significance. Taking this into account the initial differential diagnosis included pityrosporum folliculitis, immune reconstitution inflammatory syndrome (IRIS) following discontinuation of azathioprine and papular eruption of Ofuji. After multidisciplinary team discussion and liaising with immunology, it was felt that the clinical, serological and histopathological findings were in keeping with IRIS following discontinuation of long-term azathioprine. He was trialled on topical steroids, prednisone and oxytetracycline, with little improvement. His skin eruption and eosinophilia improved transiently with courses of itraconazole and ivermectin. We describe a rare case of IRIS following discontinuation of long-term azathioprine use and suspect that this entity is not well recognized. IRIS occurs when the immune system begins to recover but then responds to a previously acquired opportunistic infection with an overwhelming inflammatory response that paradoxically makes the symptoms of infection worse. Commonly seen in the context of HIV, there have been an increasing number of reports of IRIS occurring following the withdrawal of immunosuppressive therapy such as methotrexate and adalimumab. Cutaneous manifestations of IRIS range from herpes simplex infection to pityrosporum folliculitis, as seen in our patient. In this subset of patients who present with skin eruptions following the cessation of immunosuppressive therapy, IRIS should be considered in the differential. The diagnosis and management, as demonstrated in our case, is challenging, requiring a multidisciplinary approach.