title: Myeloma-related disorders in cats commonly present as extramedullary neoplasms in contrast to myeloma in human patients: 24 cases with clinical follow-up.
abstract: BACKGROUND
  Myeloma-related disorders (MRD) are rare neoplasms of plasma cells. Published case reports describe a diversity of clinical presentations with confusing terminology and diagnostic criteria as a consequence of the assumption that MRD in cats are analogous to those in dogs or humans.
  
  
  OBJECTIVE
  The aim of the study was to describe clinical, clinicopathologic and imaging findings, response to treatment, survival and possible associations with other diseases or vaccination in a large case series. A priori hypotheses were that cats with MRD commonly present with extramedullary involvement and uncommonly have radiographic bone lesions, in contrast to human patients.
  
  
  METHODS
  Twenty-four cats with MRD confirmed by cytology or histopathology and immunohistochemistry.
  
  
  METHODS
  A multicenter retrospective study was performed.
  
  
  RESULTS
  Two types of clinical presentation were observed. The first group (n = 17) had neoplasia involving abdominal organs, bone marrow, or both. All developed systemic clinical signs and paraproteinemia. Five of 7 cats that received chemotherapy improved clinically or had decreased serum globulin concentration (median survival, 12.3 months; range, 8.5-22 months). The second group comprised 7 cats with skin masses, 2 of which were paraproteinemic and developed rapidly worsening systemic signs. In cats without systemic signs, excision of the skin masses appeared to be associated with prolonged survival (up to 2.4 years). Cats with MRD commonly presented with extramedullary involvement (67%), versus humans with MRD (5%) (P < .001), and uncommonly presented with radiographic bone lesions (8%) versus humans with MRD (80%) (P < .001).
  
  
  CONCLUSIONS
  Radiographic bone lesions are uncommon in cats with MRD and extramedullary presentation is common, relative to human myeloma.
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, UK. p.j.mellor.02@cantab.net
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Mellor
authors.forename: Sean
authors.initials: S
authors.lastname: Haugland
authors.forename: Sue
authors.initials: S
authors.lastname: Murphy
authors.forename: Ken C
authors.initials: KC
authors.lastname: Smith
authors.forename: Andrew
authors.initials: A
authors.lastname: Holloway
authors.forename: Joy
authors.initials: J
authors.lastname: Archer
authors.forename: Roger M
authors.initials: RM
authors.lastname: Powell
authors.forename: Gerry A
authors.initials: GA
authors.lastname: Polton
authors.forename: Severine
authors.initials: S
authors.lastname: Tasker
authors.forename: David
authors.initials: D
authors.lastname: McCormick
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Tempest
authors.forename: Pauline E
authors.initials: PE
authors.lastname: McNeil
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Scase
authors.forename: Chris D
authors.initials: CD
authors.lastname: Knott
authors.forename: Ugo
authors.initials: U
authors.lastname: Bonfanti
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Villiers
authors.forename: David J
authors.initials: DJ
authors.lastname: Argyle
authors.forename: Michael E
authors.initials: ME
authors.lastname: Herrtage
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Day
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000473:pathology; D002371:Cat Diseases / Q000175:diagnosis* / Q000473:pathology; D002415:Cats; D003937:Diagnosis, Differential; D004285:Dogs; D005260:Female; D006801:Humans; D008297:Male; D009101:Multiple Myeloma / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D009928:Organ Specificity; D011859:Radiography; D012189:Retrospective Studies; D023981:Sarcoma, Myeloid / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D013045:Species Specificity; D016019:Survival Analysis