Correct!
5. Systemic amyloidosis
While multiple myeloma can result in the presence of amyloid proteins that are responsible for the patient’s multisystem abnormalities, the lack of osteolytic lesions at radiographic skeletal survey argues for primary systemic amyloidosis rather than multiple myeloma. Chronic lymphocytic leukemia would not explain the patient’s serum biochemical abnormalities and also typically presents with multi-station lymphadenopathy at imaging; the latter is conspicuously absent in this patient. IgG-4 disease is a reasonable thought whenever unusual multisystem abnormalities are present, but the data obtained thus far do not point towards that diagnosis. Rosai-Dorfman disease, also known as sinus histiocytosis with massive lymphadenopathy, is a rare, non-Langerhans cell reactive histiocytic disorder which typically presents as lymphadenopathy in the neck in younger patients, and is typically self-limited. The clinical, imaging, and biochemical data obtained are not consistent with this disorder. Rosai-Dorfman disease can resent as extranodal abnormalities in older patients, but is quite rare and the pattern of lung involvement is one of nodular abnormalities or septal thickening, rather than the ground-glass opacity and consolidation seen in this patient. Furthermore, Rosai-Dorman disease does not explain the patient’s nervous system abnormalities are cardiomyopathy.
The abdominal fat aspirate subtyping analysis by mass spectroscopy revealed AL lambda light chain amyloidosis. Bone marrow biopsy showed 38% plasma cells expressing monotypic lambda cytoplasmic immunoglobulin light chains, CD 38, and CD138. Free lambda light chain analysis showed a level of 2443 mg/L (normal, 5.71 to 26.3 mg/L.
Diagnosis: Systemic amyloidosis, AL immunoglobulin light chain, with systemic involvement
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