title: Acquired Fanconi syndrome with proximal tubular cytoplasmic fibrillary inclusions of λ light chain restriction.
abstract: Light chain proximal tubulopathy is a rarely reported entity associated with plasma cell dyscrasia that classically manifests as acquired Fanconi syndrome and is characterized by the presence of κ-restricted crystals in the proximal tubular cytoplasm. We herein present a case of multiple myeloma with Fanconi syndrome and acute kidney injury due to light chain proximal tubulopathy with light chain cast nephropathy. Prominent phagolysosomes and numerous irregularly shaped inclusions with a fibrillary matrix in the cytoplasm of the proximal tubules were identified on electron microscopy. A monotypic light chain of the λ type was detected in the distal tubular casts, proximal tubular cytoplasmic lysosomes and fibrillary inclusions on immunofluorescence and immune electron microscopy. This case underscores the importance of conducting careful ultrastructural investigations and immunocytologic examinations of light chains for detecting and diagnosing light chain proximal tubulopathy.
authors.affiliation: Renal Division, Department of Medicine, Peking University First Hospital; Institute of Nephrology, Peking University; Key Laboratory of Renal Diseases, Ministry of Health of China, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yao
authors.forename: Su-Xia
authors.initials: SX
authors.lastname: Wang
authors.forename: You-Kang
authors.initials: YK
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
mesh_terms: D058186:Acute Kidney Injury / Q000209:etiology* / Q000473:pathology; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001853:Bone Marrow / Q000473:pathology; D001897:Boronic Acids / Q000008:administration & dosage; D000069286:Bortezomib; D003593:Cytoplasm / Q000648:ultrastructure; D003907:Dexamethasone / Q000008:administration & dosage; D005198:Fanconi Syndrome / Q000209:etiology* / Q000473:pathology; D006801:Humans; D007147:Immunoglobulin Light Chains / Q000032:analysis*; D007687:Kidney Tubules, Proximal / Q000737:chemistry / Q000473:pathology*; D008297:Male; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D009101:Multiple Myeloma / Q000150:complications* / Q000188:drug therapy; D009194:Myeloma Proteins / Q000032:analysis*; D010588:Phagosomes / Q000648:ultrastructure; D011507:Proteinuria / Q000209:etiology; D011719:Pyrazines / Q000008:administration & dosage; D013792:Thalidomide / Q000008:administration & dosage
chemical_list: D001897:Boronic Acids; D007147:Immunoglobulin Light Chains; D009194:Myeloma Proteins; D011719:Pyrazines; D013792:Thalidomide; D000069286:Bortezomib; D003907:Dexamethasone