title: Amyloid arthropathy associated with multiple myeloma: polyarthritis without synovial infiltration of CD20+ or CD38+ cells.
abstract: OBJECTIVE
  To describe histological, immunohistochemical and ultrastructural features of synovial biopsies of amyloid arthropathy associated with multiple myeloma (MM).
  
  
  METHODS
  Synovial biopsies from affected joints of two patients with MM and amyloid arthropathy were examined with light and electron microscopy, and immunohistochemically for expression of CD3, CD8, CD20, CD38, CD68, Ki-67 and vWF. Results were compared to values from osteoarthritis (OA, n = 26), rheumatoid arthritis (RA, n = 24) and normal (n = 15) synovial membranes.
  
  
  RESULTS
  There was no or only mild lining hyperplasia. Vascular density was not elevated, and there were few Ki-67+ proliferating cells in the stroma. The Krenn synovitis score classified one specimen as "low-grade" and one as "high-grade" synovitis. CD68+ and CD3+ cells were the predominant mononuclear inflammatory cells, whereas CD20+ and CD38+ cells were absent from both synovial membrane and synovial fluid sediment. Electron microscopy demonstrated amyloid phagocytosis by synovial macrophages. In hierarchical clustering the two amyloid arthropathy specimens were more closely related to OA than to RA or normal synovium.
  
  
  CONCLUSIONS
  This first detailed immunohistological analysis of MM-associated amyloid arthropathy suggests that it is a chronic synovitis that evolves despite the loss of humoral immunity seen in advanced MM. Instead, amyloid phagocytosis by synovial macrophages likely triggers and perpetuates local disease.
authors.affiliation: TWINCORE Center for Experimental and Clinical Infection Research , Hannover , Germany .
authors.forename: Frank
authors.initials: F
authors.lastname: Pessler
authors.forename: Alexis R
authors.initials: AR
authors.lastname: Ogdie
authors.forename: Christian T
authors.initials: CT
authors.lastname: Mayer
authors.forename: Warren W
authors.initials: WW
authors.lastname: Kretzschmar
authors.forename: Lie
authors.initials: L
authors.lastname: Dai
authors.forename: Ahmed M
authors.initials: AM
authors.lastname: Elsaman
authors.forename: Eugene
authors.initials: E
authors.lastname: Einhorn
authors.forename: Veit
authors.initials: V
authors.lastname: Krenn
authors.forename: H Ralph
authors.initials: HR
authors.lastname: Schumacher
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000378:metabolism; D000368:Aged; D000686:Amyloidosis / Q000175:diagnosis* / Q000209:etiology / Q000276:immunology; D018951:Antigens, CD20 / Q000378:metabolism; D001168:Arthritis / Q000175:diagnosis* / Q000209:etiology / Q000276:immunology; D017809:Fatal Outcome; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008875:Middle Aged; D009101:Multiple Myeloma / Q000150:complications* / Q000276:immunology; D010950:Plasma Cells / Q000276:immunology / Q000378:metabolism*; D013582:Synovial Fluid / Q000276:immunology
chemical_list: D018951:Antigens, CD20; D008562:Membrane Glycoproteins; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1