AMP case report: Unexpected diagnosis of indolent systemic mastocytosis through evaluation of NGS data
July 2020—A 77-year-old woman presented at our institution for care with a remote history of lymphoma. Three years earlier she had a bone marrow biopsy performed that by report showed five percent monoclonal kappa restricted plasma cells. At the initial presentation at our institution, serum protein electrophoresis and immunofixation showed an IgA kappa paraprotein (0.52 g/dL), and bone marrow biopsy showed less than five percent plasma cells by CD138 immunohistochemistry that were kappa light chain restricted by flow cytometry, with normal renal function and calcium level. A PET-CT indicated no lytic bone lesions. These findings confirmed the diagnosis of IgA kappa monoclonal gammopathy of undetermined significance (MGUS). Her past medical history was remarkable for chronic oral ulcers for five years of possible autoimmune etiology that were responsive to methylprednisolone, a stroke, hypertension, and hyperlipidemia.