Plasma cell myeloma initially diagnosed as light-chain deposition disease on liver biopsy: A case report and literature review

Light-chain deposition disease (LCDD) is a rare condition characterized by the abnormal deposition of monoclonal light chains (LCs) in multiple organs, leading to progressive organ dysfunction. Herein, we report a case of plasma cell myeloma initially diagnosed as LCDD on liver biopsy performed for prominent cholestatic hepatitis. PATIENT CONCERNS: A 55-year-old Korean man complained of dyspepsia as the main symptom. On abdominal computed tomography performed at another hospital, the liver showed mildly decreased and heterogeneous attenuation with mild periportal edema. Preliminary liver function tests revealed abnormal results. The patient was treated for an unspecified liver disease; however, his jaundice gradually worsened, prompting him to visit our outpatient hepatology clinic for further evaluation. Magnetic resonance cholangiography revealed liver cirrhosis with severe hepatomegaly of unknown cause. A liver biopsy was performed for the diagnosis. Hematoxylin and eosin staining revealed diffuse extracellular amorphous deposits in perisinusoidal spaces with compressed hepatocytes. The deposits, which morphologically resembled amyloids, were not stained by Congo red but stained strongly positive for kappa LCs and weakly positive for lambda LCs. DIAGNOSES: Therefore, the patient was diagnosed with LCDD. Further systemic examination revealed a plasma cell myeloma. INTERVENTIONS: Fluorescence in situ hybridization, cytogenetics, and next-generation sequencing tested in bone marrow showed no abnormalities. The patient initially received bortezomib/lenalidomide/dexamethasone as the treatment regimen for plasma cell myeloma. OUTCOMES: However, he died shortly thereafter because of coronavirus disease 2019 complications. LESSONS: This case demonstrates that LCDD may present with sudden cholestatic hepatitis and hepatomegaly, and may be fatal if patients do not receive appropriate and timely treatment because of delayed diagnosis. Liver biopsy is useful for the diagnosis of patients with liver disease of unknown etiology.