E165 A clinical conundrum: distinguishing between ANCA-associated vasculitis and its mimics

Background/Aims Granulomatosis with polyangiitis (GPA) is a condition with many heterogeneous presentations. There are conditions which are also known to have similar presentations. An absence of a tissue sample supporting a diagnosis of GPA can cause diagnostic challenges. Methods We describe a case of a patient who presented as a possible GPA. Results A 52-year-old white British male presented to cardiology with symptoms of fluid overload and was diagnosed as having reduced left ventricular failure of unknown cause. He complained of a rash to his legs which looked vasculitic in nature. Dermatology had reviewed this during a previous admission eight months ago and performed a biopsy reported as a spongiotic dermatitic reaction consistent with eczema. ANCA testing was also performed, showing a positive cANCA with a PR3 of 53 IU/ml; however, this was not followed up at the time. He was referred by cardiology as a possible GPA. At a rheumatology review, the patient also complained of nosebleeds, nasal crusting, haemoptysis and significant weight loss of two stone over two years. He had a low-grade temperature of 37.5 C and reported occasional night sweats. He was also complaining of arthralgia but this was not accompanied by any joint swelling. He had normal renal function and a CRP of only 15 mg/L. A CT TAP and chest HRCT were performed, which showed widespread lymphadenopathy and some peripheral ground glass changes but no other features of GPA. ENT found that he had extensive nasal crusting and lesions that looked like erosions. Anterior rhinoplasty was limited due to obstruction in the sinuses and a biopsy was taken. The biopsy was inconclusive, showing necrotic tissue. A CT sinus was also performed, which showed mucosal ulceration and perforation of the septum. The patient disclosed a background of heavy cocaine use. He was discussed at the regional complex case MDT and it was felt that cocaine was the likely cause for his symptoms and the positive ANCA testing. However, malignancy and lymphoma is an important differential and he also underwent inguinal lymph biopsy and a haematology review. The results of the biopsy showed reactive plasmacytosis and no features of malignancy. The patient was advised cocaine cessation and was not started on immunosuppressive agents. Conclusion Drug-induced vasculitis is a diagnosis that can resemble idiopathic GPA. Cocaine can trigger a pseudovasculitis presentation either directly or through contamination with levamisole, which also causes a vasculitis-like syndrome. This poses a diagnostic challenge as this may also cause positive cANCA and PR3 antibodies. This case highlights the importance of a multidisciplinary approach to exclude other conditions, such as lymphoma or GPA.