title: Clinicopathologic correlations in multiple myeloma: a case series of 190 patients with kidney biopsies.
abstract: BACKGROUND
  Renal involvement is common in multiple myeloma. In this study, we examined kidney biopsy findings in patients with multiple myeloma and correlated them with their clinical renal and hematologic characteristics.
  
  
  METHODS
  Case series.
  
  
  METHODS
  190 Mayo Clinic patients with multiple myeloma who underwent kidney biopsy between 1997-2011 were identified from our kidney biopsy database. Patients had an established diagnosis of multiple myeloma or multiple myeloma was diagnosed shortly after the results of kidney biopsy, which prompted bone marrow biopsy.
  
  
  METHODS
  Myeloma cast nephropathy (MCN), AL amyloidosis, and monoclonal immunoglobulin deposition disease (MIDD).
  
  
  METHODS
  Renal morphologic changes, clinical renal and hematologic characteristics at kidney biopsy, renal and patient outcomes.
  
  
  RESULTS
  Paraprotein-associated lesions were seen in 73% of patients; non-paraprotein-associated lesions, in 25%; and no pathology, in 2%. The most common paraprotein-associated lesions were MCN (33%), MIDD (22%), and amyloidosis (21%). The most common non-paraprotein-associated lesions were acute tubular necrosis (9%), hypertensive arteriosclerosis (6%), and diabetic nephropathy (5%). Patients with MIDD were younger than those with MCN or amyloidosis. Urine paraprotein size and bone marrow plasma cell percentage were higher in MCN than amyloidosis or MIDD. Nephrotic syndrome was more common in amyloidosis than MIDD. Percentage of albuminuria was highest in amyloidosis and lowest in MCN. Median kidney survival from kidney biopsy was 20, 30, and 51 months for MCN, amyloidosis, and MIDD, respectively (P = 0.2). Median patient survival from multiple myeloma diagnosis was 44, 58, and 62 months for MCN, amyloidosis, and MIDD, respectively (P = 0.4).
  
  
  CONCLUSIONS
  Retrospective nature.
  
  
  CONCLUSIONS
  The spectrum of renal lesions in multiple myeloma is more heterogeneous than previously reported. Clinical features favoring amyloidosis over MIDD include older age, absence of kidney failure, presence of nephrotic syndrome, absence of hematuria, and >50% albuminuria.
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN 55905, USA. nasr.samih@mayo.edu
authors.forename: Samih H
authors.initials: SH
authors.lastname: Nasr
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Valeri
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Sethi
authors.forename: Mary E
authors.initials: ME
authors.lastname: Fidler
authors.forename: Lynn D
authors.initials: LD
authors.lastname: Cornell
authors.forename: Morie A
authors.initials: MA
authors.lastname: Gertz
authors.forename: Martha
authors.initials: M
authors.lastname: Lacy
authors.forename: Angela
authors.initials: A
authors.lastname: Dispenzieri
authors.forename: S Vincent
authors.initials: SV
authors.lastname: Rajkumar
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kyle
authors.forename: Nelson
authors.initials: N
authors.lastname: Leung
mesh_terms: D000046:Academic Medical Centers; D017677:Age Distribution; D000368:Aged; D000686:Amyloidosis / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D001707:Biopsy, Needle; D015331:Cohort Studies; D015897:Comorbidity; D016208:Databases, Factual; D018450:Disease Progression; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007674:Kidney Diseases / Q000453:epidemiology* / Q000473:pathology* / Q000628:therapy; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000453:epidemiology* / Q000473:pathology* / Q000628:therapy; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D017678:Sex Distribution; D015996:Survival Rate