title: Monotypic plasma cell interstitial nephritis as the only clinical manifestation in a patient with previously undiagnosed indolent multiple myeloma: A case report.
abstract: BACKGROUND
  Predominantly monotypic plasma cell infiltrates are an uncommon renal finding in patients with malignant lymphoplasmacytic proliferation.
  
  
  METHODS
  We report the case of a 52-year-old man with chronic kidney disease and significant proteinuria associated with a monoclonal immunoglobulin spike (IgGκ). Kidney biopsy revealed the presence of atypical multinucleated CD138 plasma cells with voluminous nuclei stained exclusively with a κ antibody. Electron microscopy showed mesangial and segmental parietal electron-dense, nonorganized hyaline deposits without immunogold labeling for the κ light chain. The bone marrow aspirate revealed 6% of apparently mature plasmocytes without dystrophy. We therefore concluded that the patient had an indolent multiple myeloma with specific renal involvement in the form of malignant monotypic interstitial plasmacytic infiltration. We initiated a specific chemotherapy regimen including bortezomib-cyclophosphamide-dexamethasone. After 4 months of follow-up, creatinine levels had improved slightly and free κ light-chain levels had decreased significantly within the normal range.
  
  
  CONCLUSIONS
  This case highlights the need to consider neoplastic interstitial plasma cell infiltration systematically in patients diagnosed with an apparently benign monoclonal gammopathy and to consider adaptation of the chemotherapy regimen, to improve renal function.
authors: Assistance Publique-Hôpitaux de Paris (AP-HP), Service de Néphrologie et Transplantation, Institut Francilien de Recherche en Néphrologie et Transplantation (IFRNT), Centre de Référence Maladie Rare Syndrome Néphrotique Idiopathique, Groupe Hospitalier Henri-Mondor/Albert-Chenevier AP-HP, Département de Pathologie, Groupe Hospitalier Henri-Mondor/Albert-Chenevier Université Paris-Est-Créteil (UPEC), Département Hospitalo-Universitaire (DHU) Virus-Immunité-Cancer (VIC), Institut Mondor de Recherche Biomédicale (IMRB), Equipe 21, INSERM U 955 AP-HP, Unité d'Hémopathies Lymphoïdes, Groupe Hospitalier Henri-Mondor/Albert-Chenevier UPEC, DHU VIC, IMRB, Equipe 9, INSERM U 955, Créteil Centre de Référence des Amyloses Primitives et des Maladies de Dépôts d'Immunoglobulines Monoclonales Département de Pathologie, Centre Hospitalier Universitaire de Poitiers, Poitiers, France.
authors: Philippe
authors: P
authors: Attias
authors: Anissa
authors: A
authors: Moktefi
authors: Marie
authors: M
authors: Matignon
authors: Jehan
authors: J
authors: Dupuis
authors: Céline
authors: C
authors: Debiais-Delpech
authors: Philippe
authors: P
authors: Grimbert
authors: Philippe
authors: P
authors: Lang
authors: Vincent
authors: V
authors: Audard
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage; D001707:Biopsy, Needle; D057210:Delayed Diagnosis; D003951:Diagnostic Errors; D018450:Disease Progression; D005500:Follow-Up Studies; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000175:diagnosis / Q000188:drug therapy* / Q000473:pathology*; D009395:Nephritis, Interstitial / Q000175:diagnosis* / Q000188:drug therapy; D010950:Plasma Cells / Q000473:pathology; D051437:Renal Insufficiency / Q000175:diagnosis / Q000209:etiology; D018570:Risk Assessment