Monoclonal gammopathy of undetermined significance causing large vessel vasculitis

A man in his late 50s presented with unilateral pain and discolouration of his fourth and fifth toes suggestive of digital ischaemia. He had a medical history of two unprovoked venous thromboembolisms in the preceding 18 months and a history of monoclonal gammopathy of undetermined significance (MGUS). A CT scan showed evidence of large vessels vasculitis in the absence of circulating antineutrophil cytoplasmic antibodies. Biopsy of the toes showed evidence of light chain and immunoglobulin deposition on immunofluorescence suggesting vasculitis secondary to his haematological diagnosis of MGUS. The patient was treated with high dose glucocorticoids and immunosuppressive treatment with a significant improvement in his symptoms and features of digital ischaemia.