title: Metal wear-induced pseudotumour following an endoprosthetic knee replacement for Ewing sarcoma.
abstract: Pseudotumours are well recognised as a complication of metal-on-metal hip arthroplasties and are thought to develop on the basis of an innate and adaptive immune response to cobalt-chrome (Co-Cr) wear particles. We report a case of a large pseudotumour that developed following a knee endoprosthetic replacement (EPR) undertaken for Ewing sarcoma. The lesion contained necrotic and degenerate connective tissue in which there were numerous scattered metal wear-containing macrophages, eosinophil polymorphs, lymphocytes, plasma cells and aseptic lymphocyte-dominated vascular-associated lesion-like lymphoid aggregates. Metal ion levels were elevated. No evidence of infection or tumour was noted and it was concluded that the lesion was most likely an inflammatory pseudotumour developing on the basis of an innate and adaptive immune response to components of Co-Cr metal wear derived from the knee EPR.
authors.affiliation: Department of Orthopaedics, Nuffield Orthopaedic Centre, University of Oxford, Oxford, OX3 7HE, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Craig
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Department of Histopathology, Nuffield Orthopaedic Centre, University of Oxford, Oxford, OX3 7HE, UK.
authors.forename: Marianna
authors.initials: M
authors.lastname: Vlychou
authors.affiliation: Department of Radiology, Nuffield Orthopaedic Centre, University of Oxford, Oxford, OX3 7HE, UK.
authors.forename: Catherine L
authors.initials: CL
authors.lastname: McCarthy
authors.affiliation: Department of Orthopaedics, Nuffield Orthopaedic Centre, University of Oxford, Oxford, OX3 7HE, UK.
authors.forename: Christopher L M H
authors.initials: CLMH
authors.lastname: Gibbons
authors.affiliation: Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Department of Histopathology, Nuffield Orthopaedic Centre, University of Oxford, Oxford, OX3 7HE, UK. nick.athanasou@ndorms.ox.ac.uk.
authors.forename: N A
authors.initials: NA
authors.lastname: Athanasou
mesh_terms: D000328:Adult; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D005266:Femoral Neoplasms / Q000188:drug therapy / Q000601:surgery*; D006104:Granuloma, Plasma Cell / Q000000981:diagnostic imaging* / Q000628:therapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008670:Metals; D049268:Positron-Emission Tomography; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000628:therapy*; D011475:Prosthesis Failure; D012512:Sarcoma, Ewing / Q000188:drug therapy / Q000601:surgery*; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D008670:Metals
keywords: Endoprosthesis; Knee; Metal wear; Pseudotumour