Thursday, April 12, 2012

Histopathology of localised adverse reactions to metal debris (ARMD) seen in association with failed metal on metal (MoM) hip arthroplasties

AS

J Clin Pathol. 2012 Mar 15. [Epub ahead of print]


Source


Department of Pathology, University hospital of North Tees and Hartlepool NHS Foundation Trust, UK.

Abstract


AimTo describe the histopathology of localised adverse reactions to metal debris (ARMD) seen in association with failed metal on metal (MoM) hip arthroplasties. The nature of aseptic lymphocytic vasculitis associated lesion (ALVAL) is investigated.Methods Periprosthetic soft tissues biopsied at time of revision from failed MoM hip arthroplasties from January 2007 to March 2011 were analysed. The inflammatory cell response was categorised into perivascular lymphocytic cuffing (ALVAL), lymphoid aggregate formation with or without germinal centres, metallosis characterised by sheets of macrophages with intracytoplasmic metallic debris and well-defined granulomas. Results123 patient samples were analysed, 36 males (29.2%) and 87 females (70.8%). Three cases showing complete tissue necrosis were excluded. Patients were reviewed between 3.27 to 69.6 months postarthroplasty, with an average of 30.92 months. 103 cases (85.8%) showed ALVAL, 18 cases also showed well-defined granulomas. Of the 103 cases with ALVAL, 60 cases also showed a diffuse chronic lymphocytic synovitis, and 40 cases showed lymphoid aggregates with germinal centres. 17 cases (14.2%) showed pure metallosis. Small vessels showing ALVAL expressed peripheral node addressin.ConclusionsARMD is a spectrum of changes comprising of pure metallosis, ALVAL and granulomatous inflammation. ALVAL, a distinctive inflammatory response seen in ARMD, is a precursor of lymphoid neogenesis. Lymphoid neogenesis documented in a variety of chronic inflammatory conditions most probably contributes to tissue necrosis and prosthetic failure seen in MoM hip arthroplasties. The role of vascular changes in contributing to necrosis is unclear at this stage.

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[15% showed Granulomas

85% showed AVAL (of those that showed AVAL)

  • 17 cases showed metallosis
  • 60 cases showed chronic lymphocytic sinovitis***
  • 40 cases showed lymphoid aggregates* with germinal centers**

*Lymphoid aggregates appear as slightly elevated nodules that may be normal in color or more red than the surrounding tissue. Sometimes they can look like small polyps. This is a harmless, non- cancerous condition.

**Germinal centers (or germinal centres; GC) are sites within lymph nodes (also within lymph nodules in peripheral lymph tissues) where mature B lymphocytes rapidly proliferate, differentiate, mutate their antibodies (through somatic hypermutation), and class switch their antibodies during a normal immune response to an infection.

***Synovitis is the medical term for inflammation of the synovial membrane. This membrane lines joints which possess cavities, known as synovial joints. The condition is usually painful, particularly when the joint is moved. The joint usually swells due to synovial fluid collection


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