IgG,kappa monoclonal gammopathy of unknown significance with AL amyloidosis simulating giant cell arteritis

Monoclonal gammopathies complicated by AL amyloidosis can mimic giant cell arteritis (GCA). We hereby present the case of a 63 year old woman in whom symptoms consistent with GCA were the first manifestations of a monoclonal gammopathy of unknown significance (MGUS) associated with amyloidosis. A 63 year old woman was admitted for temporal headache, maseterine claudication, neck and shoulder stiffness. She was recently diagnosed with carpal tunnel syndrome. On physical examination she had prominent temporal arteries, macroglosia and orthostatic hypotension. Muscular strength was normal. She had high ESR and CRP; in this clinical context, GCA was suspected. A gamma spike on serum protein electrophoresis raised the suspicion of monoclonal gammopathy (MG). Immunoelectrophoresis revealed monoclonal bands for IgG and kappa chains. Massive deposits of amyloid and no inflammation were found on temporal artery biopsy. Multiple myeloma and lymphoma were ruled out. A diagnosis of AL amyloidosis complicating MGUS was formulated. She did well on therapy with bortezomib, cyclophosphamide and dexamethasone. Cases published in medical literature reveal amyloidosis mimicking GCA in the setting of established MGUS. As far as we know, this is the first case of MGUS with IgG and kappa chains in which a GCA-like picture induced by amyloidosis was present from the very onset.