A misleading diagnosis of granulomatosis with polyangiitis disguising Whipple's disease

SIR, Whipple’s disease is an extremely rare condition (3 cases/1 000 000 inhabitants in Northern Italy), often presenting with non-specific systemic symptoms such as fatigue, weight loss and arthralgia. This is also why most patients suffering from this disease are correctly diagnosed only after several months to years. Herein, we report the case of a 43-year-old man who was referred to our unit with a diagnosis of refractory ANCA-associated granulomatous vasculitis. The diagnosis of GPA may be difficult when classical manifestations such as upper respiratory tract or renal involvement are absent. Our patient’s signs and symp- toms could be interpreted as atypical manifestations of the disease: he had multi-organ manifestations compat- ible with vasculitis (palpable purpura, arthralgia, fever, gastrointestinal symptoms including chronic diarrhoea and marked weight loss), a granulomatous necrotizing process involving multiple lymph nodes and low titre PR3-ANCA. However, since ANCA can be positive in several conditions other than GPA [4], clinicians should not use them as diagnostic of vasculitis. As demonstrated by our case and by previous reports [5, 6], Whipple’s dis- ease can mimic an atypical form of GPA, and in patients suffering from the disease C-ANCA may be present.