A literature review and expert consensus statement on diagnostics in suspected metal implant allergy

BACKGROUND

Although rare, allergic reactions to metal implants represent a diagnostic challenge in view of missing guidelines.

OBJECTIVES

To develop an European expert consensus on characteristics of metal allergy reactions and the utility of various diagnostic tools in suspected metal implant allergy.

METHODS

A nominal group technique (NGT) was applied to develop consensus statements. Initially an online literature database was created on a secure server to enable a comprehensive information. Twenty-three statements were formulated on potential aspects of metal implant allergy with a focus on diagnostics and grouped into five domains. For the consensus development, the panel of 12 experts initially did refine and reformulate those statements that were ambiguous or had unclear wording. By face-to-face (9/12) or virtual participation (3/12), an anonymous online voting was performed.

RESULTS

Consensus (≥80% of agreement) was reached in 20/23 statements. The panel agreed that implant allergy despite being rare should be considered in case of persistent unexplained symptoms. It was, however, recommended to allow adequate time for resolution of symptoms associated with healing and integration of an implant. Obtaining questionnaire-aided standardized medical history and standardized scoring of patient outcomes was also considered an important step by all experts There was broad consensus regarding the utility/performance of patch testing with additional late reading. It was recognized that the lymphocyte transformation test (LTT) has to many limitations to be generally recommended. Prior to orthopaedic implant, allergy screening of patients without a history of potential allergy to implant components was not recommended.

CONCLUSIONS

Using an expert consensus process, statements concerning allergy diagnostics in suspected metal implant allergy were created. Areas of nonconsensus were identified, stressing uncertainty among the experts around topics such as preoperative testing in assumed allergy, histological correlate of periimplant allergy and in vitro testing, which underscores the need for further research.

[Localized tenosynovial giant cell tumor : Results from the Histopathological Arthritis Register of the German Society for Orthopedic Rheumatology]

BACKGROUND

The tenosynovial giant cell tumor (pigmented villonodular synovitis) is a proliferative, mainly benign soft tissue tumor of the tendon sheaths, bursae and joints arising from the synovia. It can be divided into circumscribed localized and destructive diffuse types. Approximately 1% of all joint diseases are due to this entity. The tumor is considered as a rarity. Mostly case studies exist. For this study the focus was set on the localized type (L-TSRZT), which accounts for 90% of the diagnoses of this tumor. Given its rarity, data are limited. Therefore, the research aim was to provide data on prevalence, primary location and sensitivity of clinical versus histopathological diagnosis in a German sample.

METHODS

Based on the Histopathological Arthritis Register of the German Society for Orthopedic Rheumatology, the data of the L‑TSRZT were retrospectively analyzed (time frame 1 January 2018-28 December 2020).

RESULTS

This database contained N = 7595 cases of arthropathy. A total of n = 45 patients with the diagnosis L‑TSRZT were identified. The prevalence of the tumor was 0.6%, 95% CI [0.4%, 0.8%], or 5.9 cases per 1000. The primary location involved the finger (48.9%). In 14 of 45 cases the diagnosis was correctly determined from the clinical side, corresponding to a sensitivity of 31.1%, 95% CI [18.2%, 46.7%].

CONCLUSION

For the first time, this paper was able to provide data on a large sample for Germany. Notably, the low sensitivity of the clinical diagnosis confirms the importance of histopathology for diagnosing L‑TSRZT.

[Histopathological diagnostics of arthrofibrosis]

Joint surgery is one of the most important and successful disciplines in surgery; nevertheless, complications still occur, especially in total knee arthroplasty and surgery of the anterior cruciate ligament. A significant disease in this context is arthrofibrosis. This review article presents the cellular and molecular pathogenetic concept of arthrofibrosis, the spectrum of histopathological diagnostics and differential diagnostics and a classification into joint endoprosthesis-associated and non-joint endoprosthesis-associated arthrofibrosis is proposed. The basis of the histopathological diagnostics is the standardized tissue removal with subsequent fixation in formalin. In the case of joint implant failure and the problem of endoprosthesis-associated arthrofibrosis, the histopathological diagnostics can be carried out according to the consensus classification of synovia-like interface membrane (SLIM). Arthrofibrosis is characterized by fibrosis, a high fibroblast cellularity with immunohistochemical detection of cytoplasmic beta catenin expression. The presence of endoprosthesis-associated arthrofibrosis is probable above a threshold of 20 beta catenin positive fibroblasts per high-power field (HPF). The diagnosis of a non-endoprosthesis-associated arthrofibrosis can be classified according to the joint pathology algorithm. Diffuse non-endoprosthesis-associated arthrofibrosis is characterized by generalized proliferation of connective tissue in the whole joint and localized circumscribed arthrofibrosis is characterized by a nodose cyclops-like fibrosis. The clarification of the cause of arthrofibrosis is based on an interdisciplinary cooperation. In addition to the histopathological diagnostics, this includes clinical, surgical, biomechanical, arthroscopic, microbiological, laboratory parameter and radiological findings.

Dental Apical Inflammation Score (DAIS): Histopathological scoring for the evaluation of the apical inflammatory activity and local bone destruction

OBJECTIVE

The purpose of this study was to evaluate 210 periapical lesions with a newly created Dental Apical Inflammation Score/DAIS with regard to their inflammatory cell infiltration, bone tissue, epithelium, bacteria and foreign material.

STUDY DESIGN

Specimens were obtained from 51 different dental practices over a period of 11 months. These specimens were then sent in for histopathological routine diagnostics.

RESULTS

The DAIS classified 81 cases of Type 1 (acute inflammation = low, chronic inflammation = low), 79 cases of Type 2 (acute inflammation = low, chronic inflammation = high), 46 cases of Type 3 (acute inflammation = high, chronic inflammation = low) and 4 cases of Type 4 (acute inflammation = high, chronic inflammation = high). Bone tissue was found in 141 cases, signs for bacterial osteitis in 49 cases, cyst epithelium in 40 cases and foreign material in 27 cases. In 210 cases, cyst epithelium was evident in 27.2 % of Type 1, 15.2 % of Type 2, 8.7 % of Type 3 and in 50 % of Type 4 (p = .019). The 141 cases containing bone tissue showed signs of bacterial osteitis in 16.1 % of Type 1, 29.8 % of Type 2, 77.8 % of Type 3 and in 100 % of Type 4 (p < .001). In 64 cases, Bacteria was evident in 30 % of Type 1, 25 % of Type 2, 55 % of Type 3 and in 100 % of Type 4 (p = .013).

CONCLUSION

The DAIS could classify apical lesions with statistically significant differences. Bacterial osteitis in apical lesions was reported for the first time.

Diagnostic guidelines for the histological particle algorithm in the periprosthetic neo-synovial tissue

BACKGROUND

The identification of implant wear particles and non-implant related particles and the characterization of the inflammatory responses in the periprosthetic neo-synovial membrane, bone, and the synovial-like interface membrane (SLIM) play an important role for the evaluation of clinical outcome, correlation with radiological and implant retrieval studies, and understanding of the biological pathways contributing to implant failures in joint arthroplasty. The purpose of this study is to present a comprehensive histological particle algorithm (HPA) as a practical guide to particle identification at routine light microscopy examination.

METHODS

The cases used for particle analysis were selected retrospectively from the archives of two institutions and were representative of the implant wear and non-implant related particle spectrum. All particle categories were described according to their size, shape, colour and properties observed at light microscopy, under polarized light, and after histochemical stains when necessary. A unified range of particle size, defined as a measure of length only, is proposed for the wear particles with five classes for polyethylene (PE) particles and four classes for conventional and corrosion metallic particles and ceramic particles.

RESULTS

All implant wear and non-implant related particles were described and illustrated in detail by category. A particle scoring system for the periprosthetic tissue/SLIM is proposed as follows: 1) Wear particle identification at light microscopy with a two-step analysis at low (× 25, × 40, and × 100) and high magnification (× 200 and × 400); 2) Identification of the predominant wear particle type with size determination; 3) The presence of non-implant related endogenous and/or foreign particles. A guide for a comprehensive pathology report is also provided with sections for macroscopic and microscopic description, and diagnosis.

CONCLUSIONS

The HPA should be considered a standard for the histological analysis of periprosthetic neo-synovial membrane, bone, and SLIM. It provides a basic, standardized tool for the identification of implant wear and non-implant related particles at routine light microscopy examination and aims at reducing intra-observer and inter-observer variability to provide a common platform for multicentric implant retrieval/radiological/histological studies and valuable data for the risk assessment of implant performance for regional and national implant registries and government agencies.

[Arthur Vick Prize 2017 of the German Society of Orthopaedic Rheumatology]

The German Society of Orthopaedic Rheumatology (DGORh) honored Prof. Dr. med. Veit Krenn (MVZ-ZHZMD-Trier) with the Arthur Vick Prize 2017. With this award, scientific results with high impact on the diagnosis, therapy and pathogenetic understanding of rheumatic diseases are honored. In cooperation with pathologists and colleagues from various clinical disciplines Prof. Dr. med. Veit Krenn developed several histopathologic scoring systems which contribute to the diagnosis and pathogenetic understanding of degenerative and rheumatic diseases. These scores include the synovitis score, the meniscal degeneration score, the classification of periprosthetic tissues (SLIM classification), the arthrofibrosis score, the particle score and the CD15 focus score. Of highest relevance for orthopedic rheumatology is the synovitis score which is a semiquantitative score for evaluating immunological and inflammatory changes of synovitis in a graded manner. Based on this score, it is possible to divide results into low-grade synovitis and high-grade synovitis: a synovitis score of 1-4 is called low-grade synovitis and occurs for example in association with osteoarthritis (OA), post-trauma, with meniscal lesions and hemochromatosis. A synovitis score of 5-9 is called high-grade synovitis, e.g. rheumatoid arthritis, psoriatic arthritis, Lyme arthritis, postinfection and reactive arthritis as well as peripheral arthritis with Bechterew's disease (sensitivity 61.7%, specificity 96.1%). The first publication (2002) and an associated subsequent publication (2006) of the synovitis score has led to national and international acceptance of this score as the standard for histopathological assessment of synovitis. The synovitis score provides a diagnostic, standardized and reproducible histopathological evaluation method for joint diseases, particularly when this score is applied in the context with the joint pathology algorithm.

[Endoprosthesis failure in the ankle joint : Histopathological diagnostics and classification]

INTRODUCTION

Endoprostheses of the ankle joint show higher revision rates of 3.29 revisions per 100 component years. The aims of this study were the application and modification of the consensus classification of the synovia-like interface membrane (SLIM) for periprosthetic failure of the ankle joint, the etiological clarification of periprosthetic pseudocysts and a detailed measurement of proliferative activity (Ki67) in the region of osteolysis.

MATERIAL AND METHOD

Tissue samples from 159 patients were examined according to the criteria of the standardized consensus classification. Of these, 117 cases were derived from periprosthetic membranes of the ankle. The control group included 42 tissue specimens from the hip and knee joints. Particle identification and characterization were carried out using the particle algorithm. An immunohistochemical examination with Ki67 proliferation was performed in all cases of ankle pseudocysts and 19 control cases.

RESULTS

The consensus classification of SLIM is transferrable to endoprosthetic failure of the ankle joint. Periprosthetic pseudocysts with the histopathological characteristics of the appropriate SLIM subtype were detectable in 39 cases of ankle joint endoprostheses (33.3%). The mean value of the Ki67 index was 14% and showed an increased proliferation rate in periprosthetic pseudocysts of the ankle (p-value 0.02037).

CONCLUSION

In periprosthetic pseudocysts an above average higher detection rate of type 1 SLIM induced by abrasion (51.3%) with an increased Ki67 proliferation fraction (p-value 0.02037) was found, which can be interpreted as local destructive intraosseus synovialitis. This can be the reason for formation of pseudocystic osteolysis caused by high mechanical stress in ankle endoprostheses. A simplified diagnostic classification scoring system of dysfunctional endoprostheses of the ankle is proposed for collation of periprosthetic pseudocysts, ossifications and the Ki67 proliferation fraction.

[Adverse reactions to metal orthopedic implants after knee arthroplasty]

Based on several clinical examples, the range of adverse or hypersensitive reactions to metal implants especially after total knee replacement are presented. In general, we found the patients to generally be women who present with pain, swelling, and local or generalized eczema. Some also present with early aseptic loosening mainly in the first 4 years after implantation. For these patients, a detailed allergy-specific history should be taken and a patch test should be performed; if necessary, blood ion levels should be evaluated to exclude cobaltism. Before revision surgery and exchange of the implant we always perform arthroscopic inspection to obtain biopsies for microbiology and histopathology. Using the Consensus Classification a good evaluation for planning revision with the different implant options is possible.

International consensus on the definition and classification of fibrosis of the knee joint

AIMS

The aim of this consensus was to develop a definition of post-operative fibrosis of the knee.

PATIENTS AND METHODS

An international panel of experts took part in a formal consensus process composed of a discussion phase and three Delphi rounds.

RESULTS

Post-operative fibrosis of the knee was defined as a limited range of movement (ROM) in flexion and/or extension, that is not attributable to an osseous or prosthetic block to movement from malaligned, malpositioned or incorrectly sized components, metal hardware, ligament reconstruction, infection (septic arthritis), pain, chronic regional pain syndrome (CRPS) or other specific causes, but due to soft-tissue fibrosis that was not present pre-operatively. Limitation of movement was graded as mild, moderate or severe according to the range of flexion (90° to 100°, 70° to 89°, < 70°) or extension deficit (5° to 10°, 11° to 20°, > 20°). Recommended investigations to support the diagnosis and a strategy for its management were also agreed.

CONCLUSION

The development of standardised, accepted criteria for the diagnosis, classification and grading of the severity of post-operative fibrosis of the knee will facilitate the identification of patients for inclusion in clinical trials, the development of clinical guidelines, and eventually help to inform the management of this difficult condition. Cite this article: Bone Joint J 2016;98-B:1479-88.

[Histopathological diagnostic work-up of joint endoprosthesis-associated pathologies]

Increasing classes of joint implants and the combination of materials results in increased and wear-associated pathologies. According to the revised consensus classification, the following types can be recognized at conventional histological examination: Type I, particle-induced type; Type II, infection type; Type III, combination type; Type IV, indifferent type; Type V arthrofibrotic type; Type VI, allergic/immunological/toxic adverse reactions and Type VII, bone pathologies. Wear particles are histopathologically characterized according to the Krenn particle algorithm which focuses on a descriptive identification of wear particles and the differentiation of other nonwear-related particles. Type VII is considered histologically when there is evidence of a perivascular/interstitial lymphocytic CD20- and CD3-positive infiltrate, presence of mast cells and eosinophils, and tissue necrosis/infarction associated with implant wear material. Since wear particle-induced toxicity cannot be differentiated with certainty from hypersensitivity/allergic reaction on histological examination, immunological-allergological and clinical data should be used as supplementary criteria for the differential diagnosis. Tissue sampling should be performed from periprosthetic soft tissue with location mapping and when feasible also from bone tissue. Additional information regarding the type of implant and clinical, radiological, immunological, and microbiology data should be available to the pathologist. Further immunohistochemical studies are recommended in the following settings: infection (CD15, CD20, CD68); prosthesis-associated arthrofibrosis (β‑catenin); allergic/immunologic/toxic adverse reactions (CD20, CD3, CD4, CD8, CD117 and for T‑cell characterization T‑bet, GATA-3, and FOXP3).

[The spectrum of histomorphological findings related to joint endoprosthetics]

Approximately 230,000 total hip and 170,000 knee joint endoprostheses are implanted in Germany annually of which approximately 10% (i.e. 40,000 interventions per year) are cases of revision surgery. These interventions involve removal of a previously implanted prosthesis which has resulted in complaints and replacement with a new prosthesis. There are manifold reasons for revision surgery, the most common indication being so-called endoprosthesis loosening, which is subdivided into septic and aseptic loosening. Histomorphological studies revealed that periprosthetic tissue from endoprosthesis loosening can be classified into four types (I) wear-particle induced type, (II) infectious type, (III) combined type and (IV) fibrous type. Types I and IV represent aseptic loosening and types II and III septic loosening. Recently, the topic of implant allergy has emerged. The detection of cellular, mostly perivascular lymphocytic infiltrates is discussed as being a sign of an allergic tissue reaction. It has most frequently been observed in type I periprosthetic membranes with a dense load of metal wear, which occurs with metal-on-metal bearings. Apart from endoprosthesis loosening, arthrofibrosis is another complication of joint endoprosthetics and can cause pain and impaired function. Histopathologically, arthrofibrosis can be evaluated by a three-tiered grading system. Furthermore, bone pathologies, such as ossification, osteopenia or osteomyelitis can occur as complications of joint endoprosthetics. This review gives an overview of the whole spectrum of pathological findings in joint endoprosthetics and offers a comprehensive and standardized classification system for routine histopathological diagnostics.

Histopathological Osteomyelitis Evaluation Score (HOES) - an innovative approach to histopathological diagnostics and scoring of osteomyelitis

BACKGROUND

Treatment and diagnosis of osteomyelitis are still a challenging problem for surgeons, microbiologists and histopathologists. A direct microbiological detection of bacteria in tissues is still gold standard, but it is not always successful for example in chronic osteomyelitis and/or when an antibiotic treatment has already been started or in cases of low virulent bacteria. The goal of this study was to define diagnostic criteria of osteomyelitis, the inflammatory regression of osteomyelitis ("osteomyelitis score") under specific therapy by the correlation of histopathological and microbiological and clinical standard tests.

METHODS

In this retrospective analysis patients with medical history and clinically clear signs of bacterial infection and osteomyelitis underwent surgery between 01.01.2013 and 31.12.2012. Their formal consent was given. Tissue samples were taken during surgery according to defined criteria including surgical interventions. Histopathological diagnosis was carried out by conventional techniques based on defined criteria of bacterial infection in connective tissue, peri-implant membrane and bone. These results were carried out in tables by numbers representing the histopathological criteria of acute osteomyelitis (A1 to A3) as well as the chronic criteria (C1 and C2) in a semiquantitative way (scale 0 to 3). On the other hand a notational, graduated histopathological report was performed. Preoperative clinical diagnosis, perioperative macroscopic diagnosis, histopathological and microbiological findings were correlated.

RESULTS

Histopathological samples of 52 surgical interventions based on the preoperative diagnosis "osteomyelitis" (AOM, ECOM or COM) were included. 37 times preoperatively signs of a chronic osteomyelitis (COM), 10 times preoperatively acute osteomyelitis (AOM) was diagnosed. Another 5 patients were preoperatively diagnosed as acute exacerbated osteomyelitis (ECOM). The correlation of the histopathological infection including the inflammatory activity and microbiological detection of bacteria was 57%. The correlation between preoperative diagnosis and histopathological findings was 68%.

CONCLUSION

The relatively small 68% correlation between clinical preoperative and histopathological diagnosis and 57% correlation between preoperative clinical diagnosis and microbiological findings indicates: Clinical findings are not sufficient for the diagnosis "osteomyelitis".Clinical findings are not sufficient for the differentiation between AOM, ECOM and COM.Histopathological analysis is the critical factor for the diagnosis ("osteomyelitis") and differential diagnosis (AOM vs. COM).Histopathological analysis represents the basis for further treatment.HOES facilitates the classification of the histopathological findings.HOES is a sufficient tool for the treating physician in order to define the further treatment.

[Classification of haematogenous and post-traumatic osteomyelitis]

A classification of osteomyelitis must reflect the complexity of the disease and, moreover, provide conclusions for the treatment. The classification is based on the following eight parameters: source of infection (OM [osteomyelitis]/OT [post-traumatic OM]), anatomic region, stability of affected bone (continuity of bone), foreign material (internal fixation, prosthesis), range of infection (involved structures), activity of infection (acute, chronic, quiescent), causative microbes (unspecific and specific bacteria, fungi) and comorbidity (immunosuppressive diseases, general and local). In the long version of the classification, which was designed for scientific studies, the parameters are named by capital letters and specified by Arabic numbers, e.g., an acute, haematogenous osteomyelitis of a femur in an adolescent with diabetes mellitus, caused by Staphylococcus aureus, multi-sensible is coded as: OM2 Lo33 S1a M1 In1d Aa1 Ba2a K2a. The letters and numbers can be found in clearly arranged tables or calculated by a freely available grouper on the internet (www.osteomyelitis.exquit.net). An equally composed compact version of the classification for clinical use includes all eight parameters, but without further specification. The above-mentioned example in the compact version is: OM 3 S a Ba2 K2. The short version of the classification uses only the first six parameters and excludes causative microbes and comorbidity. The above mentioned example in the short version is: OM 3 S a. The long version of the classification describes an osteomyelitis in every detail. The complexity of the patient's disease is clearly reproducible and can be used for scientific comparisons. The for clinical use suggested compact and short versions of the classification include all important characteristics of an osteomyelitis, can be composed quickly and distinctly with the help of tables and provide conclusions for the individual treatment. The freely available grouper (www.osteomyelitis.exquit.net) creates all three versions of the classification in one step.

[Different symptoms in patients with prostheses with metal-metal bearings]

Based on several clinical case examples, this article demonstrates the different symptoms and complications in patients fitted with prostheses with metal-on-metal (MoM) bearings. We recommend an annual clinical control for patients with MoM prostheses with a prosthesis head size of 36 mm or larger. In patients who have problems tests should be carried out to measure the metal ion levels of cobalt and chromium and the metal artifact-reduced sequence by magnetic resonance imaging (MRI) or if this is not possible an ultrasound investigation. The clinical investigations should specifically target asymptomatic local swellings or hardened sites and patients should be questioned on problems with general hypersensitivity reactions (skin rash), cardiomyopathy, neurological changes including sensory changes, renal function impairment and thyroid dysfunction.

[Revised consensus classification. Histopathological classification of diseases associated with joint endoprostheses]

The revised classification of the periprosthetic membrane (synovial-like interface membrane SLIM) encompasses all pathological alterations which can occur as a result of endoprosthetic replacement of major joints and lead to a reduction in durability of prostheses. This also includes the established consensus classification of SLIM by which aseptic and septic prosthetic loosening can be subdivided into four histological types and histopathological criteria for additional pathologies: endoprosthesis-associated arthrofibrosis, immunological/allergic alterations and osseous pathologies. This revision represents the foundation for the histopathological diagnostics of the total spectrum of diseases associated with joint prostheses, is a suitable basis for a standardized diagnostic procedure and etiological clarification of endoprosthesis failure and also as a data standard for endprosthesis registers, in particular for registers based on routine data (e.g. German endoprosthesis register).

[Purulent gonarthritis resulting from H1N1 viral pneumonia]

No articles on orthopedic complications of pneumonia due to influenza A H1N1 virus have yet been published. A 44-year-old male patient was hospitalized due to the suspicion of an infected knee. During arthroscopy beta-hemolytic Streptococcus group A and Acinetobacter were found and the histopathological diagnosis of an infectious bacterial synovialitis was made. Despite resistance-oriented antibiotic treatment the patient's general condition worsened. Influenza A H1N1 virus was detected in a nasal sample and was successfully treated with Tamiflu®. If fever and elevated infection markers persist a search for the focus has to be performed including unlikely diseases such as influenza A H1N1 virus.

[Bradytrophic tissue. Its histopathological diagnosis and value in trauma surgical and orthopedic expert opinions]

Expert opinions on the musculoskeletal system are generally required for statutory or private accident insurance purposes in a variety of legal areas and with varying rules of evidence. Since they are also intended for non-medical personnel, terminology needs to be defined and must be comprehensible by all parties. Bradytrophic tissue is the most frequently evaluated aspect of the musculoskeletal system. In this context, the term"degeneration" which was formerly used has been replaced by the term"tissue structure alteration", which takes matrix changes and cellularity into consideration. Thus the significance of histopathological diagnosis of bradytrophic tissue has been put in a new light. Histopathological diagnosis is carried out on the basis of various staining methods, scores and analyses depending on the diagnostic question.

The need for speed in the management of haemophilia patients with inhibitors

Rapid control of bleeding is the key to reducing bleeding complications and thereby preserving joint and musculoskeletal function in haemophilia patients with inhibitors. However, this requires early diagnosis following the onset of bleeding and strategies for rapid treatment in an outpatient setting. Overarching themes on the need for speed in managing bleeds in haemophilia patients were examined by a panel of clinicians experienced in managing inhibitor patients and joint disease during the Third Zürich Haemophilia Forum on 8 May 2009. This report summarizes the opinions of the panel on how to achieve rapid bleeding control in inhibitor patients and areas that were identified by the panel for future research or as needing new consensus guidelines. The consensus was that home treatment should be established for haemophilia patients with inhibitors, as it is associated with a faster time to treatment, as well as improvements in the quality of life of patients and their carers. In addition, as improved haemostatic control now allows inhibitor patients to participate in a wider range of physical activities, specific guidelines are required on which types of sport and work are appropriate. It was agreed that clear, systematic approaches are needed for early diagnosis of joint and muscle bleeds in inhibitor patients, which could facilitate rapid treatment. There may be opportunities for exploiting new diagnostic techniques from osteoarthritis to enable earlier diagnosis of haemophilic arthropathy. Overall, it was concluded that greater emphasis should be placed on education and patients' psychological needs, to enable inhibitor patients to cope up more effectively with their disease.

[Histopathological degeneration score of fibrous cartilage. Low- and high-grade meniscal degeneration]

Although histopathology of meniscal degeneration plays an important role, no criteria to assess severity of the degeneration are available to date. Our aim was to create a histopathological scoring system for meniscal degeneration with good interobserver variability, taking matrix degradation and cellularity in meniscal tissue into consideration. Degeneration is classified as follows: grade 1 (low), grade 2 (intermediate), grade 3 (high). The pattern of NITEGE deposits (G1 fragment of aggrecan) was assessed immunohistochemically (n=38) and compared with the grades of degeneration. In 48% of the patients with grade 2 or 3 degeneration extracellular NITEGE deposits (specificity 100%) were found, whereas grade 1 patients showed no deposits. Extracellular NITEGE deposits correlated positively with the grade of degeneration. In all, 30 cases (10 per grade) were assessed by three pathologists (A, B, C). Grading conformity was 70% for grade 1, 66% for grade 2 and 100% for grade 3. Cohen's Kappa coefficient was 0.6--0.7 between pairs of observers. Combining grade 1 and 2 to low-grade degeneration, compared to a grade-3 high-grade degeneration achieved Kappa coefficients of between 0.93 and 1.0. This reproducible degeneration score for fibrous cartilage could form the basis for the standardized assessment of meniscal degeneration.

Molecular signatures and new candidates to target the pathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, inflammatory joint disease of unknown etiology and pronounced interpatient heterogeneity. To characterize RA at the molecular level and to uncover pathomechanisms, we performed genome-wide gene expression analysis. We identified a set of 1,054 genes significantly deregulated in pair-wise comparisons between RA and osteoarthritis (OA) patients, RA and normal donors (ND), or OA and ND. Correlation analysis revealed gene sets regulated identically in all three groups. As a prominent example secreted phosphoprotein 1 (SPP1) was identified to be significantly upregulated in RA compared with both OA and ND. SPP1 expression was found to correlate with genes expressed during an inflammatory response, T-cell activation and apoptosis, suggesting common underlying regulatory networks. A subclassification of RA patients was achieved on the basis of proteoglycan 4 (PRG4) expression, distinguishing PRG4 high and low expressors and reflecting the heterogeneity of the disease. In addition, we found that low PRG4 expression was associated with a more aggressive disease stage, which is in accordance with PRG4 loss-of-function mutations causing camptodactyly-arthropathy-coxa vara-pericarditis syndrome. Altogether we provide evidence for molecular signatures of RA and RA subclasses, sets of new candidate genes as well as for candidate gene networks, which extend our understanding of disease mechanisms and may lead to an improved diagnosis.

[Meniscal degeneration score and NITEGE expression : immunohistochemical detection of NITEGE in advanced meniscal degeneration]

BACKGROUND

Meniscal degeneration (MD) is a structural change of fibrous cartilage that is common in orthopaedic diagnostics and relevant for health insurance matters. So far, there has been neither a standardised scoring system nor an immunohistochemical marker for MD.

MATERIAL AND METHOD

In this retrospective trial, the meniscal tissue of 60 patients was assessed immunohistochemically for NITEGE (G1 fragment of the proteoglycan aggrecan) expression. NITEGE expression was correlated with defined grades of MD: little (grade 0/1), medium (grade 2), or severe (grade 3).

RESULTS

Detection of extracellular NITEGE deposits in grade 2 or 3 MD had a positive predictive value and specificity of 100%, whereas no deposits were found in grade 0/1 MD. Sensitivity in advanced MD was 55%. Detection of extracellular NITEGE correlated positively with the grade of degeneration, as did patient age and the grade of degeneration. The patient age of those with grade 0/1 MD was significantly lower than for grade 3 (p<0.0001).

CONCLUSION

The thoroughly defined degeneration score (grade 1 - grade 3 MD) is suitable to assess the severity of degeneration. Extracellular NITEGE deposits can be regarded as an immunohistochemical marker for advanced (grades 2 and 3) MD.

[Is bioptic assurance reasonable in patients with Sjögren's syndrome? From focus score to diagnosing vasculitides]

Sjögren's syndrome is an autoimmune disease which targets the salivary and lacrimal glands in particular, causing sicca syndrome. Extraglandular manifestations are often seen. Chronic sialadenitis of the parotid gland is the most common symptom to be assessed for differential diagnosis. Common HE and Giemsa slices are histopathologically examined and graduated for lymphocyte infiltration (focus): grade 0: absent, grade 1: slight, grade 2: moderate non-focal infiltration, grade 3: 1 focus (> or =50 lymphocytes) per 4 mm2, grade 4: >1 focus. Grade 3 infiltrates correspond to a focus score of 1, which is one of four disease-classifying criteria acknowledged for diagnosis. Bioptic examination is also performed to rule out different (non-) immunologic sialadenitises, such as the necrotizing or epithelioid-like form (in sarcoidosis), and the extranodal marginal-zone lymphoma. Extraglandular manifestations of Sjögren's syndrome can also be safely diagnosed by histopathological examination. Emphases lie on vasculitides and myositides. Bioptic work-up, therefore, is not only reasonable but also an essential tool for diagnostics in Sjögren's syndrome.

Tumor regression by means of magnetic drug targeting

The expression ‘magnetic drug targeting’ is understood as meaning the targeted administration of a drug, for example, a cytostatic, with the intention of optimizing the local therapeutic effect. A magnetic field strength of 0.6 T is applied externally to the body. Iron oxides are administered intravasally into a vein. Cytostatics are bonded to the iron oxides. This form of administration, also known as sluicing, is particularly suitable for cytostatics, since the intention is to achieve a high concentration of the cytostatic at the target site (site of the tumor), but to minimize the harmful effect in the rest of the tissue. A reduction in tumor volume under the magnetic field and in the liver of 45–90% has been detected by MRI.

Receptor activator of nuclear factor κB ligand is expressed in resident and inflammatory cells in aseptic and septic prosthesis loosening

OBJECTIVE

The pathogenesis of periprosthetic bone loss in aseptic and septic prosthesis loosening is unclear. There is considerable evidence that macrophages and osteoclasts play a key role in focal bone erosion and osteolysis around the prosthesis. RANKL (receptor activator of nuclear factor kappaB ligand) was shown to be a potent osteoclastogenic factor, and to be involved in bone destruction of myeloma and rheumatoid arthritis patients. Osteoprotegerin (OPG) is the natural RANKL inhibitor and may prevent periprosthetic bone loss.

METHODS

The presence and distribution of RANKL, its receptor RANK and OPG in the periprosthetic interface of septically (n = 5) and aseptically (n = 6) loosened prostheses was examined by immunohistochemistry and immunoblotting. Additionally, the immunophenotype of the inflammatory infiltrate was determined [CD3, CD68, Ki-67, tartrate-resistant acid posphatase (TRAP)].

RESULTS

Aseptic and septic cases revealed a different histopathologic pattern. However, in all cases RANKL and RANK could be demonstrated in macrophages and giant cells. In addition, RANKL detected by immunoblot analysis proved to have the same molecular weight as a recombinant RANKL used as a control (31 kD and approximately 48 kD). OPG was detected in aseptic loosening, where macrophages showed a strong staining, but multinucleated giant cells were only weakly stained. A weak OPG staining was also observed in septic loosening.

CONCLUSION

The pathogenesis of bone loss in septic loosening remains unclear, because the septic membrane bears few macrophages and giant cells, and half of them express OPG. In aseptic loosening, macrophages might not be stimulated by RANKL as a result of OPG expression. But multinucleated giant cells may be activated, as they hardly express OPG. They might be responsible for periprosthetic bone loss in aseptic loosening as a result of their RANKL and RANK expression.

[Scleroderma and fibrosing diseases]

Fibroblasts and myofibroblasts play an important role in the pathogenesis of systemic sclerosis, fibromatoses, arthrofibrosis, and Ormond's disease. These conditions are characterized by an excessive fibroblast proliferation and partly accompanied by inflammation. Scleroderma is either localized or systemic, and features additional vasculopathy. Scleroderma-like skin lesions can be found in graft-versus-host disease following allogeneic hematopoietic stem cell transplantation, complicated malignoma or can represent an adverse drug reaction. The fibromatoses are found in superficial, or as semi-malignant desmoids in deep body compartments. Ormond's disease is a chronic periaortitis of unknown origin which extends into the retroperitoneal space. The diagnostic relevance of a histopathological diagnosis of fibrosing diseases varies and ranges from a disease-supporting to a disease-defining value.

[Differential diagnosis of synovitis]

The synovial membrane is a site where many diseases with different etiologies can become manifest. Tumors and storage diseases are some of the rare conditions, whereas crystal deposition diseases, acute bacterial infections and in particular chronic uncharacteristic synovitis are frequently encountered. The latter present a diagnostic problem, because they can barely be assigned to concrete diagnoses. This report will give an overview of the differential diagnosis of joint diseases and will focus on the so-called synovitis score as a tool for the systematic evaluation of chronic uncharacteristic synovitis, providing a possibility to differentiate between degenerative and rheumatic synovitis with a specificity of 60.5% and a sensitivity of 95.5%.

[Synovitis score: value of histopathological diagnostics in unclear arthritis. Case reports from rheumatological pathological practice]

Histopathological assessment of synovial biopsies has an established value. The value for inflammatory joint diseases without standardized rating mechanisms was, however, unknown until recently. The exemplary use of the synovitis score in four cases all including recurrent bruises of the knee joint portrays its value for diagnosis and therapy. Usage of the score includes assessing the enlargement of the lining layer, cellular density of synovial stroma and leucocyte infiltration by giving each a score of 0-3 points and adding them. Presence of high-grade synovitis (>or=4 points) in all cases displayed the reason for the joint bruises within a primarily inflammatory, rheumatoid circle. In this report we show the broad variety of uses for the synovitis score dealing with cases of Lyme arthritis, rheumatoid arthritis, seronegative monarthritis and HLA-B27-positive peripheral arthritis.

Colocalization of C4d deposits/CD68+ macrophages in rheumatoid nodule and granuloma annulare: immunohistochemical evidence of a complement-mediated mechanism in fibrinoid necrosis

Rheumatoid nodule (RN) represents a palisading granuloma with central fibrinoid necrosis, which is not only a classical manifestation of rheumatoid arthritis (RA) and part of the American College of Rheumatology (ACR)-criteria, but also is its diagnostic hallmark. The pathogenesis of RN is still not fully understood. At present, only data on serum analyses indicating a complement-mediated pathogenesis in the development of RA are available. Equivalent examinations for RN have not yet been performed. Granuloma annulare (GA) represents another type of palisading granuloma. A special subtype of GA, subcutaneous GA (SGA), is an important differential diagnosis to RN. Therefore, our aim was to examine RN and SGA regarding the complement deposition (C4d) by immunohistochemical means. All RN and GA were stained by hematoxylin/eosin and different special stains. In addition, all specimens were stained immunohistochemically with antibodies against CD68. Five GA and five RN were analyzed immunohistochemically with antibodies against C4d and CD68, and evaluated using single- and doublestaining immunohistochemistry. All RN and GA displayed depositions of C4d within their central necroses and between the surrounding palisading macrophages. Most importantly, C4d/CD68 double staining was visible in the palisading macrophages next to the necroses, while macrophages in the periphery were negative for C4d but positive for CD68. The main difference between RN and GA was a quantitative phenomenon with less positively reacting macrophages in a more incomplete palisade in GA. The positive reactions of all central necroses to C4d and colocalization of CD68 and C4d suggest that a complement-mediated mechanism may be operative in the formation of fibrinoid necrosis. This mechanism may be involved in any form of "fibrinoid necrosis", since no different patterns of C4d/CD68 expression could be observed in GA. This may explain why RG/GA are not distinguishable morphologically.

[Necessity of increasing autopsy frequency following the introduction of DRGs]

With the introduction of DRGs (diagnosis related groups) in 2004, a new charging system was initiated in Germany. Changes primarily involve lump sum based charging of inpatient cases regardless of the duration or complexity of diagnostic procedures and therapy, and the equalization of costs for similar services. Calculation of DRGs also includes the costs of autopsy. This has three major consequences for autopsy practice: Quality assurance: continuous monitoring of professional quality under lump sum payment can only be permanently guaranteed and independently and reliably attained by autopsy. This is the only way to overcome the danger of abolishing essential diagnostic procedures because of economic pressure and thus risking incorrect diagnoses. Economy: additional diagnoses revealed by autopsy will, in many cases, raise calculated charges. This could have a significant financial impact. Legal certainty: autopsies increase the accuracy and objectivity of diagnoses. Thus, they protect the attending physician from incorrect charging which may be unintended but could be legally relevant, especially when the cause of death is unclear. For these reasons, autopsy should become more important in clinical routine.

Gene expression in endoprosthesis loosening: chitinase activity for early diagnosis?

The aim of the study was to identify markers for the early diagnosis of endoprosthesis loosening, for the differentiation between wear particle-induced and septic loosening and to gather new insights into the pathogenesis of endoprosthesis loosening. Gene expression profiles were generated from five periprosthetic membranes of wear particle-induced and five of infectious (septic) type using Affymetrix HG U133A oligonucleotide microarrays. The results of selected differentially expressed genes were validated by RT-PCR (n = 30). The enzyme activity and the genotype of chitinase-1 were assessed in serum samples from 313 consecutive patients hospitalized for endoprosthesis loosening (n = 54) or for other reasons, serving as control subjects (n = 259). Eight hundred twenty-four genes were differentially expressed with a fold change greater than 2 (data sets on http://www.ncbi.nlm.nih.gov/geo/ GSE 7103). Among these were chitinase 1, CD52, calpain 3, apolipoprotein, CD18, lysyl oxidase, cathepsin D, E-cadherin, VE-cadherin, nidogen, angiopoietin 1, and thrombospondin 2. Their differential expression levels were validated by RT-PCR. The chitinase activity was significantly higher in the blood from patients with wear particle-induced prosthesis loosening (p = 0.001). However, chitinase activity as a marker for early diagnosis has a specificity of 83% and a sensitivity of 52%, due to a high variability both in the disease and in the control group.

[Expression analyses for rheumatoid arthritis]

Inflammatory rheumatic diseases with their unclear aetiology are a challenge for the routine clinical practice. The dominating inflammatory processes with many facets of autoimmune phenomena have been extensively studied during the last decades. Modern high throughput technologies provide for the first time the opportunity to obtain an insight into the many different molecular aspects in one patient in parallel. Step by step, concepts can be developed to understand the relationships and interdependencies of the molecular processes and to place them in order of importance for each individual separately. Thus, studies have demonstrated that the risk of disease severity can be estimated and the response to therapy can be objectified based on molecular investigations. Exemplarily, the potential has been demonstrated that the therapeutic outcome towards a defined treatment may be predicted. Despite the high cost, it is becoming more and more obvious that an extensive increase of knowledge depends on the detection of a multitude of parameters, a task which will need to be accomplished in the near future.

[Differential diagnosis of chronic synovitis]

This review presents an algorithm for the standardised histopathological diagnostics of synovial biopsies and synovectomy specimens. In general, changes of the synovium can be inflammatory or non-inflammatory. To the latter group belong certain benign tumors such as the diffuse variant of the tenosynovial giant cell tumor, lipoma or synovial chondromatosis, additionally the rare group of storage diseases should be kept in mind. Inflammatory diseases can be discriminated into crystal-induced arthropathies such as gout and pseudogout, into granulomatous diseases such as tuberculosis, sarcoidosis and foreign-body inoculation, and into the large group of non-granulomatous synovitis. This group is by far the most common, and it often causes difficulties in assigning the histopathological findings to a concrete diagnosis. Therefore, the synovitis-score should be applied as a diagnostic device in these cases, leading to the diagnosis of a low-grade synovitis (which is associated with degenerative arthropathies) or of a high-grade synovitis (associated with rheumatic diseases), the sensitivity and specificity being 60.5% and 95.5%, respectively.

[Histopathological diagnostics in endoprosthesis loosening]

The implantation of total joint endoprostheses has become a routine procedure, being executed about 1.5 million times per year worldwide. The indications are osteoarthritis, rheumatic diseases, trauma and bone neoplasia. However, about 5-12% of patients develop pain and impaired function of the endoprosthesis within 10 years, necessitating revision surgery. During this operation, the so-called periprosthetic membrane between bone and prosthesis is removed. This connective tissue membrane has a pathogenetic impact on the loosening process and can be evaluated by histopathology. This article aims at elucidating the defined histomorphological criteria for the standardized diagnostics of periprosthetic membranes using a recently established classification system.