Systemic amyloidosis in the setting of lymphoplasmacytic lymphoma (Waldenström macroglobulinemia)
C. Order serum and urine protein electrophoresis
An older patient presenting with visual loss and pallid disc edema arouses suspicion for an anterior ischemic optic neuropathy. As the most common vasculitis of older adults in North America, giant cell arteritis (GCA) has become the poster child of the arteritic form of anterior ischemic optic neuropathy. Well established as visually morbid—with an approximate 8% rate of permanent vision loss and a 50% rate of fellow eye involvement—and responsive to corticosteroid therapy, GCA has a low threshold for diagnosis and treatment.1 However, the prevailing criteria for diagnosing GCA (the 1990 American College of Rheumatology classification) is relatively nonspecific, having a specificity of 91.3%.2 Other vasculitides, including eosinophilic granulomatosis with polyangiitis, granulomatosis with polyangiitis, hypersensitivity vasculitis, Henoch-Schönlein purpura, polyarteritis nodosa, and Takayasu arteritis, are all cited as misclassifications for GCA in the original article by Hunder et al.2