Noninfectious tissue interactions at periprosthetic interfaces

The success of hip arthroplasty is based on modern materials in addition to the continuous development of surgical techniques and clinical experience gained over six decades. The biocompatible implant materials used in hip arthroplasty can be textured or coated with biomimetic surfaces to ensure durable component ingrowth and moderate host response. Material integrity plays a critical role in the durability of the stable interface between implant components and periprosthetic tissues. Inflammation at the interfaces due to the release of degradation products from the implant materials is one of the causes of hip arthroplasty failure. This review summarizes the implant materials currently used in hip arthroplasty, their preclinical testing and the postoperative neogenesis of periprosthetic tissues, and the interactions of periprosthetic bone and the implant materials at the periprosthetic interfaces.

PDIA3 epitope-driven immune autoreactivity contributes to hepatic damage in type 2 diabetes

A diet rich in saturated fat and carbohydrates causes low-grade chronic inflammation in several organs, including the liver, ultimately driving nonalcoholic steatohepatitis. In this setting, environment-driven lipotoxicity and glucotoxicity induce liver damage, which promotes dendritic cell activation and generates a major histocompatibility complex class II (MHC-II) immunopeptidome enriched with peptides derived from proteins involved in cellular metabolism, oxidative phosphorylation, and the stress responses. Here, we demonstrated that lipotoxicity and glucotoxicity, as driven by a high-fat and high-fructose (HFHF) diet, promoted MHC-II presentation of nested T and B cell epitopes from protein disulfide isomerase family A member 3 (PDIA3), which is involved in immunogenic cell death. Increased MHC-II presentation of PDIA3 peptides was associated with antigen-specific proliferation of hepatic CD4⁺ immune infiltrates and isotype switch of anti-PDIA3 antibodies from IgM to IgG3, indicative of cellular and humoral PDIA3 autoreactivity. Passive transfer of PDIA3-specific T cells or PDIA3-specific antibodies also exacerbated hepatocyte death, as determined by increased hepatic transaminases detected in the sera of mice subjected to an HFHF but not control diet. Increased humoral responses to PDIA3 were also observed in patients with chronic inflammatory liver conditions, including autoimmune hepatitis, primary biliary cholangitis, and type 2 diabetes. Together, our data indicated that metabolic insults caused by an HFHF diet elicited liver damage and promoted pathogenic immune autoreactivity driven by T and B cell PDIA3 epitopes.

Synchrotron-based characterization of arthroprosthetic CoCrMo particles in human bone marrow

Particles released from cobalt-chromium-molybdenum (CoCrMo) alloys are considered common elicitors of chronic inflammatory adverse effects. There is a lack of data demonstrating particle numbers, size distribution and elemental composition of bone marrow resident particles which would allow for implementation of clinically relevant test strategies in bone marrow models at different degrees of exposure. The aim of this study was to investigate metal particle exposure in human periprosthetic bone marrow of three types of arthroplasty implants. Periprosthetic bone marrow sections from eight patients exposed to CoCrMo particles were analyzed via spatially resolved and synchrotron-based nanoscopic X-ray fluorescence imaging. These analyses revealed lognormal particle size distribution patterns predominantly towards the nanoscale. Analyses of particle numbers and normalization to bone marrow volume and bone marrow cell number indicated particle concentrations of up to 1 × 10¹¹ particles/ml bone marrow or 2 × 10⁴ particles/bone marrow cell, respectively. Analyses of elemental ratios of CoCrMo particles showed that particularly the particles' Co content depends on particle size. The obtained data point towards Co release from arthroprosthetic particles in the course of dealloying and degradation processes of larger particles within periprosthetic bone marrow. This is the first study providing data based on metal particle analyses to be used for future in vitro and in vivo studies of possible toxic effects in human bone marrow following exposure to arthroprosthetic CoCrMo particles of different concentration, size, and elemental composition. Graphical abstract.

Ceramic composite with gentamicin decreases persistent infection and increases bone formation in a rat model of debrided osteomyelitis

Introduction: Current methods of managing osteomyelitic voids after debridement are inadequate and result in significant morbidity to patients. Synthetic ceramic void fillers are appropriate for non-infected bone defects but serve as a nidus of re-infection in osteomyelitis after debridement. CERAMENT G (CG) is an injectable ceramic bone void filler which contains gentamicin and is currently being evaluated for use in osteomyelitic environments after debridement due to its theoretical ability to serve as a scaffold for healing while eliminating residual bacteria after debridement through the elution of antibiotics. The goal of this study was to evaluate (1) the rate of persistent infection and (2) new bone growth of a debrided osteomyelitic defect in a rat model which has been treated with either gentamicin-impregnated ceramic cement (CERAMENT G) or the same void filler without antibiotics (CERAMENT, CBVF). Methods: Osteomyelitis was generated in the proximal tibia of Sprague Dawley rats, subsequently debrided, and the defect filled with either (1) CG ( n = 20 ), (2) CBVF ( n = 20 ), or (3) nothing ( n = 20 ). Each group was euthanized after 6 weeks. Infection was detected through bacterial culture and histology. Bone growth was quantified using microCT. Results: Infection was not detected in defects treated with CG as compared with 35 % of defects ( 7 / 20 ) treated with CBVF and 50 % ( 10 / 20 ) of empty defects ( p = 0.001 ). Bone volume in the defect of CG-treated rats was greater than the CBVF (0.21 vs. 0.17, p = 0.021 ) and empty groups (0.21 vs. 0.11, p < 0.001 ) at 6 weeks after implantation. Conclusions: Ceramic void filler with gentamicin (CERAMENT G) decreased the rate of persistent infection and increased new bone growth as compared to the same void filler without antibiotics (CERAMENT) and an empty defect in a rat model of debrided osteomyelitis.

The contribution of the histopathological examination to the diagnosis of adverse local tissue reactions in arthroplasty

The histopathological examination of the periprosthetic soft tissue and bone has contributed to the identification and description of the morphological features of adverse local tissue reactions (ALTR)/adverse reactions to metallic debris (ARMD). The need of a uniform vocabulary for all disciplines involved in the diagnosis and management of ALTR/ARMD and of clarification of the parameters used in the semi-quantitative scoring systems for their classification has been considered a pre-requisite for a meaningful interdisciplinary evaluation.

This review of key terms used for ALTR/ARMD has resulted in the following outcomes: (a) pseudotumor is a descriptive term for ALTR/ARMD, classifiable in two main types according to its cellular composition defining its clinical course; (b) the substitution of the term metallosis with presence of metallic wear debris, since it cannot be used as a category of implant failure or histological diagnosis; (c) the term aseptic lymphocytic-dominated vasculitis- associated lesion (ALVAL) should be replaced due to the absence of a vasculitis with ALLTR/ALRMD for lymphocytic-predominant and AMLTR/AMRMD for macrophage-predominant reaction.

This review of the histopathological classifications of ALTR/ARMD has resulted in the following outcomes: (a) distinction between cell death and tissue necrosis; (b) the association of corrosion metallic debris with adverse local lymphocytic reaction and tissue necrosis; (c) the importance of cell and particle debris for the viscosity and density of the lubricating synovial fluid; (d) a consensus classification of lymphocytic infiltrate in soft tissue and bone marrow; (e) evaluation of the macrophage infiltrate in soft tissues and bone marrow; (f) classification of macrophage induced osteolysis/aseptic loosening as a delayed type of ALTR/ARMD; (g) macrophage motility and migration as possible driving factor for osteolysis; (h) usefulness of the histopathological examination for the natural history of the adverse reactions, radiological correlation, post-marketing surveillance, and implant registries.

The review of key terms used for the description and histopathological classification of ALTR/ARMD has resulted in a comprehensive, new standard for all disciplines involved in their diagnosis, clinical management, and long-term clinical follow-up.

Cite this article: EFORT Open Rev 2021;6:399-419. DOI: 10.1302/2058-5241.6.210013

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.

Multi-elemental nanoparticle exposure after tantalum component failure in hip arthroplasty: In-depth analysis of a single case

Porous tantalum components are widely used for complex acetabular reconstructions in revision hip arthroplasty. Multiple other metal alloys such as titanium-aluminum-vanadium or cobalt-chromium-molybdenum are principally used in artificial joint setups. We report a case of tantalum component failure being both cause and effect of a multiple metal exposure. Our aims were to assess and to characterize associated particle exposure and biological consequences. Metal level quantification revealed substantial in vivo exposure to particulate and dissociated tantalum, zirconium, chromium, cobalt, molybdenum, titanium, aluminum and vanadium in periprosthetic compartments. Aside from micron-sized particles, nanoparticles of a broad size range and elemental composition were obtained. Histological exams verified a spectrum of necrotic changes in the periprosthetic tissues. In the presented case tantalum release was accompanied by concomitance of particles originating from other utilized metals. We conclude that an overall in vivo exposure assessment is mandatory for realistic appraisal of metal toxicity and associated risks.

The Disappearing Phalanx: A Case Report of a Vascular Tumor of the Toe

We report a unique case of an epithelioid hemangioma of the third middle phalanx in which the lesion replaced the phalanx, became symptomatic, and then required resection, bone grafting, and joint arthroplasty. To the best of our knowledge, this is the first report of an epithelioid hemangioma in the toe that was treated using this approach.

Valgus Stress Radiographs Predict Lateral-Compartment Cartilage Thickness but Not Cartilage Degeneration in Varus Osteoarthritis

BACKGROUND

Intact cartilage in the lateral compartment is an important requirement for medial unicompartmental knee arthroplasty. This study sought to determine how measurements of joint space width in the lateral compartment on valgus stress radiographs compare to cartilage thickness as measured with a precise needle test, and whether cartilage thickness is a predictor of cartilage degeneration.

METHODS

A consecutive series of 100 knees undergoing total knee arthroplasty for end-stage varus osteoarthritis was studied. Twenty-eight knees were retrospectively excluded because not all data were available, leaving 72 knees (61 patients; mean age, 67 years [49-87]). On calibrated valgus stress radiographs, lateral-compartment joint space width was measured. During surgery, osteochondral samples of the distal lateral femur and the lateral tibia plateau were harvested. Cartilage thickness and histology were assessed. Cartilage thickness of tibia and femur was defined as lateral-compartment cartilage thickness.

RESULTS

Lateral-compartment joint space width on valgus stress radiographs and lateral-compartment cartilage thickness correlated well (r_s = 0.671, P < .001). However, no correlation of cartilage histology according to the osteoarthritis cartilage histopathology assessment system, and cartilage thickness on the lateral tibia plateau (r_s = -0.060, P = .614) and cartilage thickness on the distal lateral femur (r_s = -0.128, P = .282) was observed.

CONCLUSION

Valgus stress radiographs can assess combined cartilage thickness in the lateral compartment of the knee. Cartilage thickness, however, is a poor predictor of cartilage degeneration.

Radiological and histological analysis of two replaced interphalangeal joints with active subchondral bone resorption in erosive hand osteoarthritis: a novel mechanism?

The aim of this study was to describe the histological features of erosive hand osteoarthritis (EHOA), which is considered an aggressive subset of hand osteoarthritis (OA) characterized by severe local inflammation and degeneration of the distal and proximal interphalangeal joints. Two patients with EHOA underwent replacement with a cement-free press fit ceramic prosthesis of a proximal interphalangeal joint (PIPJ). Clinical and radiological data were collected and histological examination was performed. Radiological examination with histological correlation showed complete erosion of the articular cartilage with focal presence of peripheral fibrocartilaginous resurfacing, sclerosis, and remodeling of the exposed bone, osteoclastic activity with resorptive lacunae in the subchondral bone and around degenerative fibromyxoid pseudocysts, coarse trabeculation of the cancellous bone, and marginal osteophytes. The synovial membrane showed non-specific mild hypertrophy and mildly cellular fibromyxoid stroma. The histological findings in patients with EHOA suggest a pathogenesis of cartilage resorption from the subchondral bone, via osteoclastic-mediated activity and formation of periarticular reactive fibrocartilaginous proliferation with partial resurfacing of the articular surface.

Non-Lethal Type VIII Osteogenesis Imperfecta Has Elevated Bone Matrix Mineralization

CONTEXT

Type VIII osteogenesis imperfecta (OI; OMIM 601915) is a recessive form of lethal or severe OI caused by null mutations in P3H1, which encodes prolyl 3-hydroxylase 1.

OBJECTIVES

Clinical and bone material description of non-lethal type VIII OI.

DESIGN

Natural history study of type VIII OI.

SETTING

Pediatric academic research centers.

PATIENTS

Five patients with non-lethal type VIII OI, and one patient with lethal type VIII OI.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Clinical examinations included bone mineral density, radiographs, and serum and urinary metabolites. Bone biopsy samples were analyzed for histomorphometry and bone mineral density distribution by quantitative backscattered electron imaging microscopy. Collagen biochemistry was examined by mass spectrometry, and collagen fibrils were examined by transmission electron microscopy.

RESULTS

Type VIII OI patients have extreme growth deficiency, an L1-L4 areal bone mineral density Z-score of -5 to -6, and normal bone formation markers. Collagen from bone and skin tissue and cultured osteoblasts and fibroblasts have nearly absent 3-hydroxylation (1-4%). Collagen fibrils showed abnormal diameters and irregular borders. Bone histomorphometry revealed decreased cortical width and very thin trabeculae with patches of increased osteoid, although the overall osteoid surface was normal. Quantitative backscattered electron imaging showed increased matrix mineralization of cortical and trabecular bone, typical of other OI types. However, the proportion of bone with low mineralization was increased in type VIII OI bone, compared to type VII OI.

CONCLUSIONS

P3H1 is the unique enzyme responsible for collagen 3-hydroxylation in skin and bone. Bone from non-lethal type VIII OI children is similar to type VII, especially bone matrix hypermineralization, but it has distinctive features including extremely thin trabeculae, focal osteoid accumulation, and an increased proportion of low mineralized bone.

[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).

Histopathological characterization of corrosion product associated adverse local tissue reaction in hip implants: a study of 285 cases

Background

Adverse local tissue reaction (ALTR), characterized by a heterogeneous cellular inflammatory infiltrate and the presence of corrosion products in the periprosthetic soft tissues, has been recognized as a mechanism of failure in total hip replacement (THA). Different histological subtypes may have unique needs for longitudinal clinical follow-up and complication rates after revision arthroplasty. The purpose of this study was to describe the histological patterns observed in the periprosthetic tissue of failed THA in three different implant classes due to ALTR and their association with clinical features of implant failure.

Methods

Consecutive patients presenting with ALTR from three major hip implant classes (N = 285 cases) were identified from our prospective Osteolysis Tissue Database and Repository. Clinical characteristics including age, sex, BMI, length of implantation, and serum metal ion levels were recorded. Retrieved synovial tissue morphology was graded using light microscopy. Clinical characteristics and features of synovial tissue analysis were compared between the three implant classes. Histological patterns of ALTR identified from our observations and the literature were used to classify each case. The association between implant class and histological patterns was compared.

Results

Our histological analysis demonstrates that ALTR encompasses three main histological patterns: 1) macrophage predominant, 2) mixed lymphocytic and macrophagic with or without features of associated with hypersensitivity/allergy or response to particle toxicity (eosinophils/mast cells and/or lymphocytic germinal centers), and 3) predominant sarcoid-like granulomas. Implant classification was associated with histological pattern of failure, and the macrophagic predominant pattern was more common in implants with metal-on-metal bearing surfaces (MoM HRA and MoM LHTHA groups). Duration of implantation and composition of periprosthetic cellular infiltrates was significantly different amongst the three implant types examined suggesting that histopathological features of ALTR may explain the variability of clinical implant performance in these cases.

Conclusions

ALTR encompasses a diverse range of histological patterns, which are reflective of both the implant configuration independent of manufacturer and clinical features such as duration of implantation. The macrophagic predominant pattern and its mechanism of implant failure represent an important subgroup of ALTR which could become more prominent with increased length of implantation.

Autoimmune response to transthyretin in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common pediatric rheumatological condition. Although it has been proposed that JIA has an autoimmune component, the autoantigens are still unknown. Using biochemical and proteomic approaches, we identified the molecular chaperone transthyretin (TTR) as an antigenic target for B and T cell immune responses. TTR was eluted from IgG complexes and affinity purified from 3 JIA patients, and a statistically significant increase in TTR autoantibodies was observed in a group of 43 JIA patients. Three cryptic, HLA-DR1-restricted TTR peptides, which induced CD4⁺ T cell expansion and IFN-γ and TNF-α production in 3 out of 17 analyzed patients, were also identified. Misfolding, aggregation and oxidation of TTR, as observed in the synovial fluid of all JIA patients, enhanced its immunogenicity in HLA-DR1 transgenic mice. Our data point to TTR as an autoantigen potentially involved in the pathogenesis of JIA and to oxidation and aggregation as a mechanism facilitating TTR autoimmunity.

OARSI osteoarthritis cartilage histopathology assessment system: A biomechanical evaluation in the human knee

The study compared the OARSI osteoarthritis cartilage histopathology assessment system with the biomechanical quality of human in vivo cartilage samples. In a prospective cohort study, 84 patients (100 knees) with varus deformity of the knee were included between May, 2010 and January, 2012. Osteochondral samples underwent biomechanical and histologic analysis. The dynamic modulus significantly (p < 0.001) decreased with each advancing grade of degeneration from OARSI Grade 0 (surface intact) to OARSI Grade 4 (erosion). For the aggregate modulus, there were significant (p < 0.001) differences between OARSI Grade 0 and OARSI Grade 1 as well as between OARSI Grade 1 and OARSI Grade 2. From OARSI Grade 2 to OARSI Grade 5, no differences in aggregate modulus occurred. The new OARSI grading system provides useful information about the functional properties of cartilage. There is a significant difference in cartilage stiffness between samples with intact surface and no signs of degeneration (OARSI Grade 0) and samples with intact surface and early signs of arthritis (OARSI Grade 1). Surgeons performing joint preserving procedures have to be aware that in knees with an intact cartilage surface (OARSI Grade 0/1), significant differences in the biomechanical properties may exist.

Glomus Tumors in the Foot: Case Series

Glomus tumors are painful, benign neoplasms that frequently are associated with delayed diagnosis. Commonly in the hand, they rarely present in the foot. The purpose of this case series is to characterize the clinical presentation, radiology, pathology, and surgical outcomes associated with foot glomus tumors. We reviewed our pathology database for patients with foot glomus tumors diagnosed between 1995 and 2013. Medical records including physician notes, pathology, and radiology were reviewed. Eleven patients had foot glomus tumors excised at our institution during the study period. The mean age was 45.4 (range = 28-60) years. One patient was lost to follow-up. Mean follow-up for the remaining 10 patients was 44.7 (range = 3-142) months. Ten tumors were located in the subungual region, while 1 was located in the plantar pulp of the distal phalanx. All patients presented with pain. Point tenderness, cold hypersensitivity, and nail abnormalities were variably documented but frequently present. Four patients had had prior surgery for an ingrown toenail prior to presentation at our institution. Six patients had preoperative magnetic resonance imaging studies, which were diagnostic of glomus tumor in all cases except one. Radiographs failed to provide diagnosis in all 8 patients for whom they were obtained. Postoperatively, all patients had complete symptom relief with no recurrences.In conclusion, this case series demonstrates that foot glomus tumors frequently present with classic symptoms including pain, point tenderness, and cold hypersensitivity. When clinically suspected, magnetic resonance imaging should be obtained. Marginal excision results in symptom relief and cure.

LEVEL OF EVIDENCE

Therapeutic, Level IV: Case series.

Adverse local tissue reaction (ALTR) associated with corrosion products in metal-on-metal and dual modular neck total hip replacements is associated with upregulation of interferon gamma-mediated chemokine signaling

Adverse local tissue reactions (ALTR) associated with tribocorrosion following total hip arthroplasty (THA) have become a significant clinical concern in recent years. In particular, implants featuring metal-on-metal bearing surfaces and modular femoral stems have been reported to result in elevated rates of ALTR. These tribocorrosion-related tissue reactions are characterized by marked necrosis and lymphocytic infiltration, which contrasts sharply with the macrophagic and foreign body giant cell inflammation associated with polyethylene wear particle induced peri-implant osteolysis. In this study, we characterize tribocorrosion-associated ALTR at a molecular level. Gene expression profiling of peri-implant tissue around failing implants identifies upregulation of numerous inflammatory mediators in ALTR, including several interferon gamma inducible factors, most notably the chemokines MIG/CXCL9 and IP-10/CXCL10. This expression profile is distinct from that associated with polyethylene wear induced osteolysis, which is characterized by induction of markers of alternative macrophage activation, such as chitotriosidase (CHIT-1). Importantly, MIG/CXCL9 and IP-10/CXCL10 are also elevated at the protein level in the synovial fluid and, albeit more moderately, the serum, of ALTR patients, raising the possibility that these factors may serve as circulating biomarkers for the early detection of ALTR in at-risk patients.

Prevention of Defective Placentation and Pregnancy Loss by Blocking Innate Immune Pathways in a Syngeneic Model of Placental Insufficiency

Defective placentation and subsequent placental insufficiency lead to maternal and fetal adverse pregnancy outcome, but their pathologic mechanisms are unclear, and treatment remains elusive. The mildly hypertensive BPH/5 mouse recapitulates many features of human adverse pregnancy outcome, with pregnancies characterized by fetal loss, growth restriction, abnormal placental development, and defects in maternal decidual arteries. Using this model, we show that recruitment of neutrophils triggered by complement activation at the maternal/fetal interface leads to elevation in local TNF-α levels, reduction of the essential angiogenic factor vascular endothelial growth factor, and, ultimately, abnormal placentation and fetal death. Blockade of complement with inhibitors specifically targeted to sites of complement activation, depletion of neutrophils, or blockade of TNF-α improves spiral artery remodeling and rescues pregnancies. These data underscore the importance of innate immune system activation in the pathogenesis of placental insufficiency and identify novel methods for treatment of pregnancy loss mediated by abnormal placentation.

Implant based differences in adverse local tissue reaction in failed total hip arthroplasties: a morphological and immunohistochemical study

BACKGROUND

Adverse local tissue reaction (ALTR) is characterized by periprosthetic soft tissue inflammation composed of a mixed inflammatory cell infiltrate, extensive soft tissue necrosis, and vascular changes. Multiple hip implant classes have been reported to result in ALTR, and clinical differences may represent variation in the soft tissue response at the cellular and tissue levels. The purpose of this study was to describe similarities and differences in periprosthetic tissue structure, organization, and cellular composition by conventional histology and immunohistochemistry in ALTR resulting from two common total hip arthroplasty (THA) implant classes.

METHODS

Consecutive patients presenting with ALTR from two major hip implant classes (N = 54 patients with Dual-Modular Neck implant; N = 14 patients with Metal-on-Metal implant) were identified from our prospective Osteolysis Tissue Database and Repository. Clinical characteristics including age, sex, BMI, length of implantation, and serum metal ion levels were recorded. Retrieved synovial tissue morphology was graded using light microscopy and cellular composition was assessed using immunohistochemistry.

RESULTS

Length of implantation was shorter in the DMN group versus MoM THA group (21.3 [8.4] months versus 43.6 [13.8] months respectively; p < 0.005) suggesting differences in implant performance. Morphologic examination revealed a common spectrum of neo-synovial proliferation and necrosis in both groups. Macrophages were more commonly present in diffuse sheets (Grade 3) in the MoM relative to DMN group (p = 0.016). Perivascular lymphocytes with germinal centers (Grade 4) were more common in the DMN group, which trended towards significance (p = 0.066). Qualitative differences in corrosion product morphology were seen between the two groups. Immunohistochemistry showed features of a CD4 and GATA-3 rich lymphocyte reaction in both implants, with increased ratios of perivascular T-cell relative to B-cell markers in the DMN relative to the MoM group (p = 0.032).

CONCLUSION

Our results demonstrate that both implant classes display common features of neo-synovial proliferation and necrosis with a CD4 and GATA-3 rich inflammatory infiltrate. Qualitative differences in corrosion product appearance, macrophage morphology, and lymphocyte distributions were seen between the two implant types. Our data suggests that ALTR represents a histological spectrum with implant-based features.

Does intraarticular inflammation predict biomechanical cartilage properties?

BACKGROUND

Intact cartilage in the lateral compartment is an important requirement for medial unicompartmental knee arthroplasty (UKA). Progression of cartilage degeneration in the lateral compartment is a common failure mode of medial UKA. Little is known about factors that influence the mechanical properties of lateral compartment cartilage.

QUESTIONS/PURPOSES

The purposes of this study were to answer the following questions: (1) Does the synovial fluid white blood cell count predict the biomechanical properties of macroscopically intact cartilage of the distal lateral femur? (2) Is there a correlation between MRI grading of synovitis and the biomechanical properties of macroscopically intact cartilage? (3) Is there a correlation between the histopathologic assessment of the synovium and the biomechanical properties of macroscopically intact cartilage?

METHODS

The study included 84 patients (100 knees) undergoing primary TKA for varus osteoarthritis between May 2010 and January 2012. All patients underwent preoperative MRI to assess the degree of synovitis. During surgery, the cartilage of the distal lateral femur was assessed macroscopically using the Outerbridge grading scale. In knees with an Outerbridge grade of 0 or 1, osteochondral plugs were harvested from the distal lateral femur for biomechanical and histologic assessment. The synovial fluid was collected to determine the white blood cell count. Synovial tissue was taken for histologic evaluation of the degree of synovitis.

RESULTS

The mean aggregate modulus and the mean dynamic modulus were significantly greater in knees with 150 or less white blood cells/mL synovial fluid compared with knees with greater than 150 white blood cells/mL synovial fluid. There was no correlation among MRI synovitis grades, histopathologic synovitis grades, and biomechanical cartilage properties.

CONCLUSIONS

The study suggests that lateral compartment cartilage in patients with elevated synovial fluid white blood cell counts has a reduced ability to withstand compressive loads.

LEVEL OF EVIDENCE

Level III, diagnostic study. See the Instructions for Authors for a complete description of levels of evidence.

Age-related carbonylation of fibrocartilage structural proteins drives tissue degenerative modification

Aging-related oxidative stress has been linked to degenerative modifications in different organs and tissues. Using redox proteomic analysis and illustrative tandem mass spectrometry mapping, we demonstrate oxidative posttranslational modifications in structural proteins of intervertebral discs (IVDs) isolated from aging mice. Increased protein carbonylation was associated with protein fragmentation and aggregation. Complementing these findings, a significant loss of elasticity and increased stiffness was measured in fibrocartilage from aging mice. Studies using circular dichroism and intrinsic tryptophan fluorescence revealed a significant loss of secondary and tertiary structures of purified collagens following oxidation. Collagen unfolding and oxidation promoted both nonenzymatic and enzymatic degradation. Importantly, induction of oxidative modification in healthy fibrocartilage recapitulated the biochemical and biophysical modifications observed in the aging IVD. Together, these results suggest that protein carbonylation, glycation, and lipoxidation could be early events in promoting IVD degenerative changes.

[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).

Salmonella septic arthritis of the knees in a patient with systemic lupus erythematosus

Hematogenous Salmonella osteomyelitis is uncommon in immunocompetent hosts, but occurs with some regularity in immunosuppressed patients affected by systemic lupus erythematosus (SLE). Surgical debridement with resection of compromised tissue is central to the surgical management of osteomyelitis. Persistence of septic arthropathy may result from inadequate debridement, areas of osteonecrosis (ON), and an abnormal cellular and humoral dysregulation characteristic of SLE. We describe a 53-year-old Hispanic female with SLE on immunosuppressive therapy, who developed acute salmonella-induced septic arthritis and osteomyelitis of both knees associated with ON and recurrent SLE synovitis. She received prolonged antibiotic therapy and an extensive surgical debridement as part of a successful two-stage bilateral total knee replacement. This report illustrates the significance of Salmonella enterica infection in SLE patients, and the role of underlying bone and joint pathology such as bone infarcts, sub-acute osteomyelitis, and SLE synovitis.

Magnetic resonance imaging findings in symptomatic versus asymptomatic subjects following metal-on-metal hip resurfacing arthroplasty

BACKGROUND

Although pseudotumors have been reported at the sites of well-functioning and painful metal-on-metal hip prostheses, there are no objective data on the magnitude of the adverse reaction. This observational study was performed to investigate the ability of modified magnetic resonance imaging (MRI) to detect and quantify adverse synovial responses in symptomatic and asymptomatic subjects following metal-on-metal hip resurfacing. We hypothesized that the magnitude of the synovial reactions would be greater in symptomatic patients.

METHODS

Sixty-nine patients (seventy-four hips) with hip resurfacing were divided into three groups: asymptomatic (twenty-two hips), symptomatic with a mechanical cause (twenty), and unexplained pain (thirty-two). The volume of synovitis was calculated on MRI for all patients.

RESULTS

Synovitis was detected in fifteen asymptomatic hips (68%), fifteen (75%) with symptoms with a mechanical causes, and twenty-five (78%) with unexplained pain. The mean volume (and standard deviation) of the synovitis in these groups was 5 ± 7 cm³, 10 ± 16 cm³, and 31 ± 47 cm³, respectively. The coefficient of repeatability between the examiners was 1.8 cm³ for measurement of synovitis. Of the thirteen subjects with revision arthroplasty, six had an adverse local tissue reaction. This subgroup had the highest volumes of synovitis on MRI.

CONCLUSIONS

An adverse synovial reaction was detected on MRI in both symptomatic and asymptomatic subjects. We found a larger volume of synovitis in symptomatic patients; this increase reached significance only in the group with an adverse local tissue reaction. Synovial volume on MRI may be a valuable marker in the longitudinal assessment of asymptomatic patients with a metal-on-metal hip resurfacing and in identifying patients with adverse local tissue reaction.

Multimodality treatment of a multifocal osteoblastoma-like tumor of the lower extremity

Osteoblastoma-like tumor is a rare condition with limited information on its orthopedic management in the current medical literature. The tumor histologically resembles an osteoblastoma, although the radiographic features are similar to those observed in primary vascular lesions. The treatment in the previously reported cases involved aggressive procedures including amputation, en bloc resection, and chemotherapy because of the uncertainty regarding the biological behavior of the tumor. We present a case of this entity that was successfully treated by a combination therapy including intralesional curettage with adjuvant cryotherapy, in situ and intravenous administration of bisphosphonates and radioablation.

Acute inflammation with induction of anaphylatoxin C5a and terminal complement complex C5b-9 associated with multiple intra-articular injections of hylan G-F 20: a case report

OBJECTIVE

The purpose of this case report was to investigate local immune mechanisms present during an acute inflammatory flare initiated by viscosupplementation with hylan G-F 20 in a patient with osteoarthritis (OA) and past meniscectomy.

EXPERIMENTAL DESIGN

A patient with a history of bilateral OA and partial left knee meniscectomy, who had received three injections of hylan G-F 20, was diagnosed with an acute flare reaction in the left knee. Her chart was evaluated for clinical, radiological, and laboratory findings and for clinical follow-up. Histopathological synovial examination and real-time polymerase chain reaction (RT-PCR) for genes with major roles in local inflammation and enzyme-linked immunosorbent assays (ELISAs) for markers of complement activation and cytokines were performed. To study the impact of the inflammatory and immune features we compared the case patient with groups of three representative OA and three rheumatoid arthritis (RA) patients.

RESULTS

The patient exhibited evidence of highly increased acute phase reactant C-reactive protein (CRP) in the blood. The pathological examination of the synovial membrane identified abundant fibrinous exudate with numerous particles of hyaluronan surrounded by a dense infiltrate of neutrophils and eosinophils. The synovium had moderate hypertrophy and sclerosis as well as an inflammatory infiltrate predominantly composed of T lymphocytes and macrophages with scattered perivascular eosinophils and neutrophils. Immunoperoxidase staining identified numerous deposits of C5b-9 in the fibrinous exudates and the synovial membrane of the patient. Similar findings were observed in the RA patients, whereas deposits were rare in OA synovial samples. In addition, both anaphylatoxin C5a and the terminal complement complex C5b-9 were present at high levels, comparable to those in RA patients. The levels of mRNA for interleukin-1 beta (IL-1β), IL-6, and the neutrophil marker myeloperoxidase (MPO) were markedly increased compared to those in the RA and OA patients.

CONCLUSIONS

This present study is indicative of a pseudo-septic acute inflammatory reaction in response to local accumulation of hylan G-F 20 with the activation of complement and local invasion of pro-inflammatory cells.

Engraftment of peripheral blood mononuclear cells from systemic lupus erythematosus and antiphospholipid syndrome patient donors into BALB-RAG-2-/- IL-2Rγ-/- mice: a promising model for studying human disease

OBJECTIVE

To construct a humanized mouse model of systemic lupus erythematosus (SLE) that resembles the human disease in order to define the pathophysiology and targets for treatments.

METHODS

We infused peripheral blood mononuclear cells (PBMCs) from SLE patients into BALB- RAG-2-/- IL-2Rγ-/- double-knockout (DKO) mice, which lack T cells, B cells, and natural killer cells. PBMCs from 5 SLE patients and 4 normal donors were infused intravenously/intraperitoneally at a density of 3-5×10(6) cells per animal into nonirradiated 4-5-week-old mice. We evaluated the engraftment of human CD45+ cells and monitored the plasma levels of human IgG, anti-double-stranded DNA (anti-dsDNA) antibody, and anticardiolipin antibody (aCL), as well as proteinuria and kidney histology.

RESULTS

There was 100% successful engraftment in 40 DKO mice infused with human PBMCs. In the PBMC fraction from SLE PBMC-infused DKO (SLE-DKO) mice and normal donor PBMC-infused DKO (ND-DKO) mice, an average of 41% and 53% human CD45+ cells, respectively, were observed at 4 weeks postengraftment, with 70-90% CD3+ cells. There were fewer CD3+CD4+ cells (mean±SEM 5.5±2.1%) and more CD3+CD8+ cells (79.4±3.6%) in the SLE-DKO mice as in the SLE patients from which the PBMCs were derived. CD19+ B cells and CD11c+ monocytic cells were found in the spleen, lung, liver, and bone marrow. There was no significant difference in plasma levels of human IgG and anti-dsDNA antibodies between SLE-DKO and ND-DKO mice. Levels of aCL were significantly higher in all SLE-DKO mice infused with PBMCs from an SLE patient who had high titers of aCL. SLE-DKO mice had proteinuria, human IgG deposits in the kidneys, and a shorter life span. In SLE-DKO mice engrafted with PBMCs from the aCL-positive patient, we found microthrombi and infiltration of CD3+, CD8+, and CD19+ cells in the glomeruli, recapitulating the human antiphospholipid syndrome in these mice.

CONCLUSION

We established a novel humanized SLE-DKO mouse exhibiting many of the immunologic and clinical features of human SLE.

A complete deficiency of Hyaluronoglucosaminidase 1 (HYAL1) presenting as familial juvenile idiopathic arthritis

We describe a single consanguineous family with three affected children exhibiting knee and/or hip pain associated with swelling. Detailed clinical evaluation demonstrated diffuse joint involvement with an unusual proliferative synovitis on MRI. Synovial biopsies were notable for an infiltration of macrophages with abundant cytoplasm filled with faintly basophilic vacuoles. We used homozygosity mapping with a panel of 262,000 single nucleotide polymorphism markers to identify a homozygous stretch of 40.52 Mb on chromosome 3p22.3 - 3p13 that segregated with the arthropathy in the family. Of the 378 genes in the interval, the three hyaluronoglucosaminidase genes were considered good candidates based on the phenotype. Dideoxy sequencing identified a homozygous deletion in HYAL1, c.104delT, resulting in a premature termination codon, p.Val35AlafsX25, found in all three affected children. Enzymatic analysis confirmed total HYAL1 deficiency in the three affected children. This confirms the diagnosis of Mucopolysaccharidosis IX (MPS IX) which has only been described in a single patient to date. In contrast to the previously described MPS IX patient, our three patients display a phenotype limited to the joints, suggesting that this is the primary manifestation of HYAL1 deficiency.

Leiomyoma of the foot: sonographic features with pathologic correlation

Leiomyomas arising outside of the uterus and gastrointestinal tract are uncommon, though these benign soft tissue neoplasms have been reported in the lower extremity and foot. To our knowledge, the sonographic appearance of a lower extremity leiomyoma has not been described in the literature. This report involves a case of leiomyoma of the foot and its sonographic imaging features. MR correlative imaging and histopathology are also provided.

Sarcomatoid carcinoma of the small intestine: a case report and review of the literature

Sarcomatoid carcinoma of the small bowel is rare; to our knowledge, 19 cases have been reported to date in the English literature under several names. We report an additional case occurring in the jejunum of a 55-year-old man. The tumor was a polypoid 7.5-cm mass, which infiltrated the full thickness of the intestinal wall and the serosa of an adhesed loop of small bowel. On microscopic examination, the neoplasm was composed of sheets of spindle cells; focally, an anaplastic component was present, including tumor giant cells with bizarre nuclei. On immunohistochemical stains, tumor cells were positive for cytokeratin 7, cytokeratin AE1/AE3, vimentin, and focally, epithelial membrane antigen. No staining for cytokeratin 20 was found. Sarcomatoid carcinoma must be kept in mind in the differential diagnosis of malignant spindle cell tumors of the small bowel. As consensus regarding the terminology of these rare tumors is being reached, immunohistochemical stains are essential for accurate diagnosis.

BMP signaling components are expressed in human fracture callus

Of the various growth factors involved in the healing response after a fracture, bone morphogenetic proteins (BMPs) are emerging as key modulators. BMPs exert their effects by binding to a complex of type I and type II receptors leading to the phosphorylation of specific downstream effector proteins called Smads. The current study examined the presence of BMP signaling components in human callus obtained from five nascent malunions undergoing fracture fixation. These callus samples represented various stages of bone healing and a mixture of endochondral and intramembraneous bone healing. We performed immunohistochemistry on the callus, using antibodies for BMP (BMP-2,-3,-4,-7), their receptors (BMPR-IA, -IB, -II), and phosphorylated BMP receptor-regulated Smads (pBMP-R-Smads). Active osteoblasts showed fairly consistent positive staining for all BMPs that were examined, with the immunoreactivity most intense for BMP-7 and BMP-3. Immunostaining for BMPs in osteoblasts appeared to colocalize with the expression of BMPR-IA, -IB, and -II. Positive immunostaining for pBMP-R-Smads suggests that the BMP receptors expressed in these cells are activated. Staining for BMPs in cartilage cells was variable. The immunostaining appeared stronger in more mature cells, whereas staining for BMP receptors in cartilage cells was less ubiquitous. However, the expression of pBMP-R-Smads in cartilage cells suggests active signal transduction. Fibroblast-like cells also had a variable staining pattern. Overall, our findings indicate the presence of BMPs, their various receptors, and activated forms of receptor-regulated Smads in human fracture callus. To the best of our knowledge, this is the first study that documents the expression of these proteins in human fracture tissue. Complete elucidation of the roles of BMP in bone formation will hopefully lead to improved fracture healing care.

Sarcoma in association with bone infarcts. Report of five cases

Sarcoma associated with bone infarct is rare, and only 41 well-documented cases have been published. We describe five additional patients, three women and two men, aged 39 to 57 years. The tumors involved the femur (three patients), tibia (one patient), and humerus (one patient). In three patients, the infarcts were idiopathic. Radiologic evidence of malignancy was found in all patients, and bone infarcts were suspected in four. Four of the patients had malignant fibrous histiocytoma and one an osteosarcoma. Histologically, bone infarcts were seen in all patients, but in three they were mostly replaced by tumor. Portions of intact infarcts were seen adjacent to the tumor, indicating that they had preceded the development of the sarcoma. No hypercellular or atypical reparative tissue was found in the infarcted bones or in three additional uncomplicated infarcts studied from the same patients. The pathogenesis of sarcoma arising in bone infarct is unknown. The prognosis is poor; four of our five patients died within 2 years.

Malignant mesenchymoma

BACKGROUND

Malignant mesenchymomas are rare soft tissue tumors that contain two or more distinct histologic subtypes of sarcoma within the same tumor (exclusive of a fibrosarcomatous or hemangiopericytomatous component). They are generally considered high grade neoplasms and are associated with a poor prognosis, although experience with these tumors is limited.

METHODS

We report 8 patients seen at our center over the last 22 years and describe the clinical course of a patient with a malignant mesenchymoma arising in the retroperitoneum whose experience typifies the aggressive behavior of this tumor.

RESULTS

All eight patients had large, high grade tumors located in the retroperitoneum or thigh. Six of the 8 died of disease and 2 were alive with disease at a median of 30 months from diagnosis.

CONCLUSIONS

Malignant mesenchymoma represents a particularly aggressive form of soft tissue sarcoma. Our experience with this disease highlights the need for more effective treatment strategies for these patients.

Resection of brain metastases from sarcoma

BACKGROUND

Brain metastases from sarcoma are rare, and data concerning the treatment and results of therapy are sparse.

METHODS

We retrospectively reviewed 25 patients with brain metastases from sarcoma of skeletal or soft-tissue origin, surgically treated in a single institution during 20 years.

RESULTS

In 18 patients the brain lesion was located supratentorially, and in 7 patients infratentorially. Median age at brain metastasis diagnosis was 25 years. Median time from primary diagnosis to diagnosis of brain metastasis was 26.7 months. Lung metastases were present in 19 patients and in 8 patients they were synchronous with the brain lesion. Pulmonary metastases were resected in 12 patients (48% of total, and 63% of those with pulmonary lesions). The overall median survival from diagnosis of the primary sarcoma was 38 months and from craniotomy was 7 months. The presence or absence of lung lesions did not alter the median survival as calculated from diagnosis of brain metastasis. Overall percent survival was 40% at 1 year and 16% at 2 years.

CONCLUSIONS

Because brain metastases from sarcoma are refractory to alternative treatment, surgical excision is indicated when feasible. Brain metastases from sarcoma are uncommon, usually occurring with or after lung metastasis. Long-term survival is possible in some patients.

Liposarcoma of the anterior mediastinum and thymus. A clinicopathologic study of 28 cases

We studied 28 cases of anterior mediastinal liposarcoma occurring in 16 males and 12 females with a mean age of 43 years (range, 14-72). Presenting symptoms included dyspnea (four cases) and chest pain (four cases), although 11 tumors were detected incidentally by routine chest radiography. Seven cases were believed to be located within the thymus. Most (i.e., 25) of the cases were of low grade, with the well-differentiated lipoma-like or sclerosing subtypes constituting 60% and the myxoid subtype constituting 28%; the remaining 12% exhibited mixed features. Three cases were pleomorphic type. Several low-grade tumors exhibited widespread, dense aggregates of mature-appearing lymphocytes and plasma cells, which occasionally obscured the mesenchymal nature of the neoplasm, suggesting instead a lymphoid neoplasm or a reactive fibroinflammatory condition. The three high-grade tumors showed combinations of pleomorphic and round cell patterns, with focal myxoid areas. Of the cases grossly arising within the thymus, only one showed extensive thymic tissue within the lesion ("thymoliposarcoma"); six others exhibited residual thymus peripheral to the tumor. Clinical follow-up in 23 cases revealed recurrence in seven patients (31.8%), with a mean interval to recurrence of 3 years. Eight patients died (mean survival, 2.6 years), one postoperatively and three following a recurrence. Fifteen patients were alive (mean survival, 2 years), four with recurrent tumor. The myxoid tumors had a somewhat more aggressive course than the well-differentiated tumors. Metastases were not observed in any of the patients.

Malignant smooth muscle tumors presenting as mediastinal soft tissue masses. A clinicopathologic study of 10 cases

BACKGROUND

Smooth muscle tumors presenting as mediastinal soft tissue masses are extremely rare and often are mistaken for other neoplastic conditions.

METHODS

Ten cases of patients with malignant smooth muscle tumors presenting as mediastinal soft tissue masses were studied and correlated with their clinical behavior. Tissues were examined histologically and with immunohistochemical stains in all cases, and by electron microscopy in two cases.

RESULTS

The patients' ages ranged from 26 to 71 years (mean, 56 years); three were women, and seven were men. Three cases were located in the anterior mediastinum and seven in the posterior mediastinum. The patients with anterosuperior mediastinal tumors all presented with signs and symptoms referable to their lesions; the patients with posterior mediastinal masses (with the exception of one) were all asymptomatic. Grossly, the lesions were well circumscribed and unencapsulated, ranging from 6 to 18 cm in greatest dimension and showed a homogeneous, rubbery cut surface with prominent cystic and myxoid areas. The tumors in all patients appeared to arise from the soft tissues within the mediastinum and were unrelated to adjacent structures. In three patients, the tumors compressed and displaced the esophagus without infiltrating its wall, and in one patient, the tumor was found in close proximity, although unattached, to a large vessel. Histologically, the lesions exhibited a spectrum of morphologic appearances that ranged from low grade leiomyosarcoma with mild-to-moderate nuclear atypia and low mitotic activity (< 3/10 high power fields [HPFs]), to high grade tumors with marked nuclear pleomorphism, extensive areas of necrosis, and high mitotic activity (> 10 mitoses/10 HPFs). One case was characterized by a striking epithelioid morphology with large, round cells arranged in small clusters; another was associated with an incidental microscopic focus of thymic seminoma in the adjacent thymus. Immunohistochemical stains in all cases showed positive labeling of the tumor cells with smooth muscle actin, desmin, and vimentin antibodies. Electron microscopy in two cases showed features of smooth muscle differentiation, i.e., spindle cells surrounded by basal lamina material, immature cell junctions, and abundant intracytoplasmic filaments with focal condensations. All patients were treated with surgical excision. On follow-up, three patients with Stage IIIb and IVa tumors died 2-7 years after surgery, and two patients with Stage Ib and IIb were alive and well 4 and 6 years after surgery, respectively.

CONCLUSION

Leiomyosarcomas may arise as primary tumors originating from mediastinal soft tissues in both anterior and posterior compartments. Because of their large size and frequent areas of cystic and myxoid degeneration, they may be confused histologically with neural or other neoplasms. As with their counterparts in other soft tissue locations, histologic grade and clinical stage are the most useful parameters for assessing prognosis.

Malignant smooth muscle tumors presenting as mediastinal soft tissue masses. A clinicopathologic study of 10 cases

BACKGROUND

Smooth muscle tumors presenting as mediastinal soft tissue masses are extremely rare and often are mistaken for other neoplastic conditions.

METHODS

Ten cases of patients with malignant smooth muscle tumors presenting as mediastinal soft tissue masses were studied and correlated with their clinical behavior. Tissues were examined histologically and with immunohistochemical stains in all cases, and by electron microscopy in two cases.

RESULTS

The patients' ages ranged from 26 to 71 years (mean, 56 years); three were women, and seven were men. Three cases were located in the anterior mediastinum and seven in the posterior mediastinum. The patients with anterosuperior mediastinal tumors all presented with signs and symptoms referable to their lesions; the patients with posterior mediastinal masses (with the exception of one) were all asymptomatic. Grossly, the lesions were well circumscribed and unencapsulated, ranging from 6 to 18 cm in greatest dimension and showed a homogeneous, rubbery cut surface with prominent cystic and myxoid areas. The tumors in all patients appeared to arise from the soft tissues within the mediastinum and were unrelated to adjacent structures. In three patients, the tumors compressed and displaced the esophagus without infiltrating its wall, and in one patient, the tumor was found in close proximity, although unattached, to a large vessel. Histologically, the lesions exhibited a spectrum of morphologic appearances that ranged from low grade leiomyosarcoma with mild-to-moderate nuclear atypia and low mitotic activity (< 3/10 high power fields [HPFs]), to high grade tumors with marked nuclear pleomorphism, extensive areas of necrosis, and high mitotic activity (> 10 mitoses/10 HPFs). One case was characterized by a striking epithelioid morphology with large, round cells arranged in small clusters; another was associated with an incidental microscopic focus of thymic seminoma in the adjacent thymus. Immunohistochemical stains in all cases showed positive labeling of the tumor cells with smooth muscle actin, desmin, and vimentin antibodies. Electron microscopy in two cases showed features of smooth muscle differentiation, i.e., spindle cells surrounded by basal lamina material, immature cell junctions, and abundant intracytoplasmic filaments with focal condensations. All patients were treated with surgical excision. On follow-up, three patients with Stage IIIb and IVa tumors died 2-7 years after surgery, and two patients with Stage Ib and IIb were alive and well 4 and 6 years after surgery, respectively.

CONCLUSION

Leiomyosarcomas may arise as primary tumors originating from mediastinal soft tissues in both anterior and posterior compartments. Because of their large size and frequent areas of cystic and myxoid degeneration, they may be confused histologically with neural or other neoplasms. As with their counterparts in other soft tissue locations, histologic grade and clinical stage are the most useful parameters for assessing prognosis.

Non-germ-cell or teratomatous malignant tumors showing additional rhabdomyoblastic differentiation, with emphasis on the malignant Triton tumor

Non-germ-cell or teratomatous malignant tumors showing additional rhabdomyoblastic differentiation can be divided into three groups. Group I consists of tumors with only sarcomatous differentiation. Included in this group are malignant mesenchymoma, dedifferentiated chondrosarcoma, and the dedifferentiated retroperitoneal liposarcoma. Epithelial or Sertoli-Leydig cell elements represent the second component of tumors in group II. The best known tumor in this group is the malignant mullerian mixed tumor, but other well described tumors with rhabdomyosarcomatous differentiation are the carcinosarcoma, mullerian adenosarcoma, Sertoli-Leydig cell tumor, mammary cystosarcoma, and blastomas. Most of the tumors in groups I and II are derived from mesenchymal tissue. A neuroectodermal origin is shared by all tumors in group III. This includes the medulloblastoma, retinoblastoma and, most frequently, the malignant Triton tumor. The tumors in all three groups are clinically malignant to a varying degree.

Long-term carcinogenicity bioassays on propylene administered by inhalation to Sprague-Dawley rats and Swiss mice

Propylene was administered by inhalation, 7 hours daily, 5 days weekly, at a concentration of 5000, 1000, 200 and 0 ppm, to Sprague-Dawley rats and Swiss mice. Groups of 120 male and 120 female rats (high-dose and controls) or 100 male and 100 female rats (mid- and low-dose) were treated for 104 weeks, and groups of 100 male and 100 female mice (each dose and controls) for 78 weeks. The animals were kept under observation until spontaneous death. Under the tested experimental conditions, the monomer was not shown to be carcinogenic.

Long-term carcinogenicity bioassays on acrylonitrile administered by inhalation and by ingestion to Sprague-Dawley rats

Sprague-Dawley rats were exposed to acrylonitrile by inhalation at 40, 20, 10, 5 and 0 ppm, 4 hours daily, 5 days weekly, for 52 weeks and at 60 ppm, 4-7 hours daily, 5 days weekly. The latter treatment was started on 13-week-old breeders, and male and female offspring (12-day-embryos). The breeders and part of the offspring were exposed for 104 weeks; the other part of the offspring was exposed for 15 weeks only. Sprague-Dawley rats were also exposed to acrylonitrile by ingestion (stomach tube), in olive oil, at 5 mg/kg b.w., once daily 3 times weekly for 52 weeks. Under the tested experimental conditions, acrylonitrile was shown to be carcinogenic in Sprague-Dawley rats when given by inhalation and did not produce any carcinogenic effect when given by ingestion. In the inhalation experiment, acrylonitrile caused an increase in different types of tumors and the most noticeable acrylonitrile-related tumor was encephalic glioma.

Long-term carcinogenicity bioassays on methylene chloride administered by ingestion to Sprague-Dawley rats and Swiss mice and by inhalation to Sprague-Dawley rats

Methylene chloride was administered to Sprague-Dawley rats and Swiss mice by ingestion (stomach tube), in olive oil, at the doses of 500, 100 and 0 mg/kg body weight, once daily, 4-5 days weekly, for 64 weeks, and to Sprague-Dawley rats by inhalation, at the concentration of 100 and 0 ppm, 7 hours daily, for 5 days weekly. The inhalatory treatment was started on 13-week-old breeders, and male and female offspring (12-day embryos). The breeders and part of the offspring were exposed for 104 weeks; the other part of the offspring was exposed for 15 weeks only. The most important findings were: (1) the increased incidence of pulmonary tumors in male mice treated by ingestion at 500 mg/kg body weight; (2) a not-significant increase in total malignant tumors in rats exposed by inhalation at 100 ppm for 104 weeks; and (3) a not-significant increase in total malignant mammary tumors in female rats given methylene chloride by ingestion at 500 mg/kg body weight.

Long-term carcinogenicity bioassays on trichloroethylene administered by inhalation to Sprague-Dawley rats and Swiss and B6C3F1 mice

Trichloroethylene was administered by inhalation, 7 hours daily, 5 days weekly, for 8 weeks, at concentrations of 600, 100 and 0 ppm, to Sprague-Dawley rats and Swiss mice; and for 104 weeks to Sprague-Dawley rats; and for 78 weeks to Swiss and B6C3F1 mice at concentrations of 600, 300, 100 and 0 ppm. The animals were kept under observation until spontaneous death. In the experiments reported herein, 3768 animals were studied. Under the experimental conditions, trichloroethylene appears to be carcinogenic in rats and mice (particularly in male Swiss mice). The most relevant finding was the dose-related increased incidence of Leydig cell tumors in male rats, and the onset of few renal tubuli adenocarcinomas at the highest dose, always in rats (4/130 males and 1/130 females). The renal tubuli adenocarcinomas were preceded by, and associated with, a characteristic lesion of the kidney: tubuli cell karyomegaly (megalonucleocytosis).

Long-term carcinogenicity bioassays on styrene administered by inhalation, ingestion and injection and styrene oxide administered by ingestion in Sprague-Dawley rats, and para-methylstyrene administered by ingestion in Sprague-Dawley rats and Swiss mice

Styrene was administered to Sprague-Dawley rats by inhalation (300, 100, 50, 25, 10 and 0 ppm, 4 hours daily, 5 days weekly, for 52 weeks); by gavage (250, 50 and 0 mg/kg b.w. in olive oil, once daily, 4-5 days weekly, for 52 weeks), by intraperitoneal injection (50 and 0 mg in olive oil, four times at 2-month intervals), by subcutaneous injection (50 and 0 mg in olive oil, once). Styrene oxide was administered to Sprague-Dawley rats by gavage as styrene (250, 50 and 0 mg/kg b.w. in olive oil, once daily, 4-5 days weekly, for 52 weeks). The animals were kept under observation until spontaneous death. Para-methylstyrene was also administered by gavage to Sprague-Dawley rats at 500, 250, 50, 10 and 0 mg/kg b.w., and to Swiss mice at 250, 50, 10 and 0 mg/kg b.w., in olive oil, once daily, 5 days weekly, for 108 weeks and 78 weeks, respectively. The study was terminated when the survival rate reached 50% in at least one experimental group. Styrene, when given by inhalation, was found to cause an increase in total (benign and malignant) and malignant mammary tumors. Styrene oxide produced a high incidence of tumors in the forestomach (papillomas, acanthomas, and in situ and invasive squamous cell carcinomas). Para-methylstyrene was not shown to be carcinogenic.

Incidence of pancreatic tumors and tumor precursors in Sprague-Dawley rats after administration of olive oil

We studied the pancreata of 280 (140 males and 140 females) olive-oil-treated and 240 (120 males and 120 females) untreated Sprague-Dawley rats of the breed used at the BT Experimental Unit of the Bologna Institute of Oncology. Extra-virgin olive oil was administered by stomach tube, once daily, for 4-5 days weekly, for 2 years. The animals were kept under observation for as long as 130 weeks. Only a borderline increase in acinar cell adenomas and adenocarcinomas was observed. We found no increase in endocrine oncologic lesions.

Long-term carcinogenicity bioassays on three chlorofluorocarbons (trichlorofluoromethane, FC11; dichlorodifluoromethane, FC12; chlorodifluoromethane, FC22) administered by inhalation to Sprague-Dawley rats and Swiss mice

Three propellant chlorofluorocarbons, namely trichlorofluoromethane (FC11), dichlorodifluoromethane (FC12), and chlorodifluoromethane (FC22) were administered by inhalation at a concentration of 5000, 1000 and 0 ppm, 4 hours daily, 5 days weekly, for 104 and 78 weeks, to rats and mice, respectively. The animals were kept under observation until spontaneous death. Under the experimental conditions, all three compounds failed to show any carcinogenic effects.

Further evidence of benzene carcinogenicity. Results on Wistar rats and Swiss mice treated by ingestion

Wistar rats and Swiss mice were treated by ingestion (stomach tube) with benzene in olive oil at a dose of 500 and 0 mg/kg b.w. once daily, 4-5 days weekly, for 104 weeks (rats) or for 78 weeks (mice). In Wistar rats, benzene caused Zymbal gland carcinomas, carcinomas of the oral cavity, and carcinomas of the nasal cavities, and an increase in the incidence of total malignant tumors. In Swiss mice, benzene produced Zymbal gland carcinomas and dysplasias and an increase in the incidence of mammary carcinomas (in females), lung tumors, and total malignant tumors. These experiments further confirm that benzene is a multipotential carcinogen as was shown before by long-term bioassays performed on Sprague-Dawley rats in the same Experimental Unit.