Two cases of systemic antineutrophil cytoplasmic antibody (ANCA) vasculitis in the setting of chronic lymphocytic leukaemia and angioimmunoblastic lymphadenopathy type T cell lymphoma are reported. The two patients had fever of unknown origin associated with cutaneous vasculitis and "pulmonary-renal syndrome" with alveolar haemorrhage. Despite anti-infectious treatments, steroids, and chemotherapy, the vasculitis had a fatal paraneoplastic course in several weeks. When infection is excluded in patients with malignancy, atypical features should be promptly investigated for systemic vasculitis, and an ANCA test performed.