Biomaterial-induced sarcoma: A novel model to study preneoplastic change

Undifferentiated Pleomorphic Sarcoma Mimicking Breast Implant-Associated Anaplastic Large Cell Lymphoma

Breast implant augmentation is a low-risk procedure with few life-threatening complications, most commonly rupture or leakage and contraction of the capsule. Breast implant-associated (BIA) malignancies are rare. Anaplastic large cell lymphoma (ALCL) is the most well-known neoplastic condition associated with breast augmentation. Carcinomas arising in association with implants have been reported but are rarer than ALCL. BIA-mesenchymal tumors are extremely rare and most are locally aggressive fibromatosis. To date, only eight cases of BIA sarcomas have been reported. Herein, we describe a case of silicone BIA-undifferentiated pleomorphic sarcoma (UPS) that was initially mistaken for ALCL because of a significant clinical and radiological overlap in presentation and imaging. Here, we present the morphological and molecular features of this rare neoplasm. We reviewed the existing literature related to BIA sarcomas to highlight the importance of considering this diagnosis in cases of recurrent ALCL-negative BIA effusions.

Etiology, pathogenesis, and management of angiosarcoma associated with implants and foreign body: Clinical cases and research updates

Angiosarcomas are rare and highly malignant soft tissue sarcomas originating from endothelial cells lining the lymphatic or vascular system. While they predominantly emerge from (sub)cutaneous regions, occurrences have been reported throughout the body. The etiology of angiosarcoma remains elusive in most clinical cases. Nevertheless, several prognosis risk factors play a pivotal role, including chronic lymphedema, therapeutic irradiation, environmental carcinogens, familial syndromes, and the presence of foreign materials like metallic objects and biomedical implants. Despite evidence implicating retained foreign material in angiosarcoma development, understanding its prognosis and pathogenesis remains limited. The pathogenesis of angiosarcoma appears to involve a complex interplay of chronic inflammation, tissue remodeling, and genetic factors that create a conducive microenvironment for malignant transformation. Management of these sarcomas remains challenging due to their infiltrative nature owing to the high chance of metastasis and local recurrence. The primary treatment modalities currently include surgery, radiotherapy, and chemotherapy, but recent advances in targeted immunotherapy and gene therapy hold promise for more effective approaches. This comprehensive review delves into the potential etiological and pathogenic roles of foreign materials, such as metallic objects, biomedical implants, and biomaterials, in the development of angiosarcoma. Further research into the underlying molecular mechanisms could provide valuable insights for tailored management and developing novel targeted therapeutic strategies.

An Update on Implant-Associated Malignancies and Their Biocompatibility

Implanted medical devices are widely used across various medical specialties for numerous applications, ranging from cardiovascular supports to orthopedic prostheses and cosmetic enhancements. However, recent observations have raised concerns about the potential of these implants to induce malignancies in the tissues surrounding them. There have been several case reports documenting the occurrence of cancers adjacent to these devices, prompting a closer examination of their safety. This review delves into the epidemiology, clinical presentations, pathological findings, and hypothesized mechanisms of carcinogenesis related to implanted devices. It also explores how the surgical domain and the intrinsic properties and biocompatibility of the implants might influence the development of these rare but serious malignancies. Understanding these associations is crucial for assessing the risks associated with the use of medical implants, and for developing strategies to mitigate potential adverse outcomes.

Indications for the removal of implants after fracture healing: A comparison between human and veterinary medicine

Indications for implant removal after fracture healing are still under debate in both human and veterinary medicine. Although hardware removal is a common procedure, it should not be undertaken lightly. Intra and post-operative complications are common and a thorough evaluation of the risks and benefits should be performed. This review aimed to collect and summarise published data on the indications for implant removal in small animals, compare the collected data with human and equine medicine, and investigate the existence of guidelines for this purpose. There is no international consensual agreement for implant removal after fracture healing, neither in small animals nor in human orthopaedics. Decision-making processes are still controversial in some scenarios, thus clear evidence-based protocols for implant removal are needed.

High-grade pleomorphic sarcoma associated with an orthopedic implant: a rare case report

The use of prosthetic implants and metallic materials is widespread in modern orthopedic surgery. Generally, these materials are non-toxic and inert. Nevertheless, a few cases of malignancy associated with certain implants have been documented in the literature. It has been reported that some components of these implants have carcinogenic properties. In most cases, these tumors are high-grade sarcomas that occur in the bone or soft tissue adjacent to the implant site. Here we present the case of a 53-year-old patient who underwent intramedullary nailing of the tibia and developed a pleomorphic sarcoma at the implant site 18 years later.

Resorbable Mg2+-Containing Phosphates for Bone Tissue Repair

Materials based on Mg2+-containing phosphates are gaining great relevance in the field of bone tissue repair via regenerative medicine methods. Magnesium ions, together with condensed phosphate ions, play substantial roles in the process of bone remodeling, affecting the early stage of bone regeneration through active participation in the process of osteosynthesis. In this paper we provide a comprehensive overview of the usage of biomaterials based on magnesium phosphate and magnesium calcium phosphate in bone reconstruction. We consider the role of magnesium ions in angiogenesis, which is an important process associated with osteogenesis. Finally, we summarize the biological properties of calcium magnesium phosphates for regeneration of bone.

The occurrence of osteosarcoma after tibial fracture repair in a dog

Background:

There are few detailed reports on implant-associated sarcoma in dogs; however, loose implants, metal type, and infection have not been shown as specific risk factors for this condition.

Case Description:

A 14-year-old spayed female Labrador retriever was referred to our hospital with a main complaint of chronic right hind lameness after previous tibial fracture repair. On radiographs, rupture of the bone plate and screws with swelling of the surrounding soft tissue was observed, and osteosarcoma (OSA) was diagnosed after histopathological examinations. During amputation surgery, a plastic band was found associated with the implant.

Conclusion:

Veterinary surgeons should be aware of implant-associated OSA and refrain from using non-medical materials in the implants. Furthermore, they should recommend the removal of orthopedic implants after fracture repair.

Radiation-Induced Sarcoma After Heterotopic Ossification Prophylaxis: A Case Report

CASE

Heterotopic ossification (HO) is a pathological formation of bone in nonosseous tissue and is a common complication of orthopaedic procedures. Radiotherapy is often used to prevent HO despite the small risk of secondary malignancy. Here, we report a case of a patient who developed a periprosthetic, radiation-induced sarcoma after delivery of a single fraction of 7 Gy for HO prophylaxis. This sarcoma was found to lie entirely within the treatment field and occurred within 5 years of radiation.

CONCLUSION

Appropriate counseling regarding radiation-induced sarcoma formation should be provided to patients considering radiotherapy for this HO prophylaxis.

Extraskeletal osteosarcoma misdiagnosed as heterotopic ossification after periprosthetic femoral fracture: A case report

Extraskeletal osteosarcoma is a malignant tumor of soft tissue characterized by osteoid production and has a very low prevalence, comprising approximately 4% of all osteosarcomas and about 1% of all soft tissue sarcomas, and a total of about 350 cases have been reported until now. Heterotopic ossification is a pathological finding of bony tissue in soft tissue regions such as muscle, skin and subcutaneous tissue. We report a case of an 86-year-old woman with a history of total hip arthroplasty (THA), in which open reduction and internal fixation were done for periprosthetic femoral Fracture. The ossified lesion misdiagnosed as heterotopic ossification initially was diagnosed as extraskeletal osteosarcoma at 6 months after the surgery. Both extraskeletal osteosarcoma and heterotopic ossification have no definite symptoms, but show radiopaque shadows on simple radiograph. Therefore, careful attention and thorough evaluation with multiple imaging tests may be necessary for the differential diagnosis of these entities.

Best Practice Approach for Assessment of Microchip-associated Tumors in Preclinical Safety Studies: Position of the Registry of Industrial Toxicology Animal-data (RITA)

Microchip (passive radio-frequency identification device) implantation is a common and widely employed means of animal identification in laboratory animal facilities. However, these devices have been associated with tumors of the skin and subcutis in rodents. While microchip-associated tumors are rare, they pose a challenge for accurate diagnosis and documentation in preclinical toxicity studies. Documentation of these tumors should differentiate microchip-associated lesions with spontaneously occurring or test article-induced tumors. Standardizing criteria for microchip-associated lesions will aid the diagnostic process and allow for preclinical regulatory standardization. To this end, the Registry of Industrial Toxicology Animal-data have developed clear recommendations for diagnosis and documentation of microchip-associated lesions.

Retrospective analysis of corrosion and ion release from retrieved cast stainless steel tibia plateau leveling osteotomy plates in dogs with and without peri-implant osteosarcoma

OBJECTIVE To evaluate and compare surface and cross-sectional structure as well as localized electrochemical corrosion and ion release for cast stainless steel (SS) tibia plateau leveling osteotomy (TPLO) plates retrieved from dogs with and without osteosarcoma (OSA) and to compare these findings with similar variables for forged SS TPLO plates retrieved from dogs. SAMPLE 47 TPLO plates explanted from 45 client-owned dogs (22 cast plates from dogs with OSA, 22 cast plates from dogs without OSA, and 3 forged plates from dogs without OSA). PROCEDURES Histologic evaluations of tissue samples collected from implant sites at the time of plate retrieval were performed to confirm implant site tumor status of each dog. Surfaces and metallographic cross sections of retrieved plates were examined, and the microcell technique was used to obtain local electrochemical corrosion and ion release measurements. RESULTS Findings indicated that all cast SS plates demonstrated high spatial variability of their electrochemical surface properties and inhomogeneous superficial and cross-sectional composition, compared with forged plates. Greater metal ion release was observed in cast plates than in forged plates and in cast plates from dogs with OSA than in cast or forged from dogs without OSA. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that accumulation of metal ions from implants could be a trigger for neoplastic transformation in neighboring cells. Metal ion release caused by corrosion of implants that do not comply with recommended standards of the American Society for Testing and Materials International or the International Organization for Standardization could potentially place patients at increased risk of tumor development.

Biocompatibility and safety of PLA and its copolymers

PLA and its copolymers are commonly used for a wide variety of applications. While they are considered to be biocompatible, side effects resulting from their implantation have been reported. The implantation of biomaterials always results in a foreign body reaction. Such a reaction has also been reported following PLA and its copolymers. This article reviews the process of inflammatory reaction that is to be expected following implantation of PLA, and it highlights specific cases in which the inflammatory reaction can result in safety concerns. The authors also review selected cases from different medical fields to demonstrate possible clinical side effects resulting from its use.

Carcinogenic potential of polypropylene mid-urethral slings: what do we know so far?

INTRODUCTION AND HYPOTHESIS

Polypropylene (PP) mesh has come under increased scrutiny owing to previous FDA safety communications regarding the risks of mesh in trans-vaginal surgery and ensuing class action litigation for post-operative complications. Additional concerns have been raised regarding a possible link between implanted PP mesh and the long-term development of malignancy. Until recently, no research was specifically committed to the exploration of such a link. Our objective was to provide an overview of the recent literature focusing on any association between the use of PP mesh for midurethral sling procedures and the development of malignancy.

METHODS

Multiple online research databases were searched for information related to any possible carcinogenic potential of PP mesh.

RESULTS

There was no increased incidence in the development of malignancy after midurethral sling procedures using PP mesh in any of the studies.

CONCLUSION

Given the scarcity of evidence suggesting otherwise, the likelihood of PP mesh causing malignancy is exceptionally low. However, with few studies and an unknown latency period between exposure and diagnosis, more observational data would prove useful to exclude causality.

Implant-associated neoplasia in dogs: 16 cases (1983-2013)

OBJECTIVE

To characterize clinical and pathological features of implant-associated neoplasms in dogs.

DESIGN

Retrospective case-control study.

ANIMALS

16 dogs with implant-associated neoplasia and 32 control dogs with osteosarcoma without implants. Procedures: Medical records of dogs with tumors associated with metallic implants (cases) treated between 1983 and 2013 were reviewed. Two dogs with naturally occurring osteosarcoma (controls) were matched to each case on the basis of tumor location, age, and sex.

RESULTS

Median time from implant placement to diagnosis of neoplasia was 5.5 years (range, 9 months to 10 years). Pelvic limbs were most frequently affected, including the tibia (8/16) and femur (5/16), with 1 neoplasm involving both the femur and pelvis. Implant: associated tumors most commonly affected the diaphysis (15/16), with osteosarcomas significantly more likely to involve the long bone diaphysis in case dogs than in control dogs with naturally occurring osteosarcomas. Osteosarcoma was the most common tumor, accounting for 13 of 16 implant-associated tumors. For 7 of these osteosarcoma cases, review of histopathology results enabled subclassification into osteoblastic nonproductive (n = 3), chondroblastic (2), osteoblastic productive (1), and fibroblastic (1) groups. Three case dogs had a diagnosis of histiocytic sarcoma, fibrosarcoma, and spindle cell sarcoma.

CONCLUSIONS AND CLINICAL RELEVANCE

Results of this study highlighted important anatomic differences between spontaneous and implant-associated neoplasia in dogs.

Spontaneous cutaneous soft tissue sarcoma with differentiation into fibroblasts in a Sprague-Dawley rat

A small mass with an ulcer was found in the skin of the dorsal cervix of a 7-month-old male Sprague-Dawley rat. Histologically, the central region of the tumor showed a high cellular density with oval-shaped tumor cells arranged in an alveolar pattern and thin collagen fiber bundles. The peripheral region of the tumor had a low cellular density with short spindle- or polygonal-shaped tumor cells surrounded by abundant collagen fiber bundles. Immunohistochemically, the tumor cells were strongly positive for vimentin and proliferating cell nuclear antigen, and a portion of the short spindle- or polygonal-shaped cells located in the peripheral region of the tumor were positive for S100A4. However, the tumor cells were negative for alpha-smooth muscle actin, desmin, S100, chromogranin A, neurofilament, CD68, Iba-1, cytokeratin 20, von Willebrand factor, melanosome, and anti-melanoma. Electron microscopically, the tumor cells had an abundance of rough endoplasmic reticulum, the Golgi apparatus, and a few intracellular collagen fibrils, showing fibroblastic features. Considering the lack of diagnostic differentiation, the tumor was diagnosed as an undifferentiated malignant mesenchymal tumor and classified as a soft tissue sarcoma with differentiation into fibroblasts in a portion of the tumor cells.

Total hip arthroplasty-related osteogenic osteosarcoma: case report and review of the literature

BACKGROUND

Orthopedic implant-related sarcoma is an exceedingly rare, but a known complication of total hip arthroplasty (THA).

CASE PRESENTATION

The authors describe clinical and radiologic features, histologic appearance, and treatment of osteogenic osteosarcoma located in the proximal femoral diaphysis associated with an unstable femoral prosthesis following THA in a 65-year-old male patient. The patient with HLA-B27 positive ankylosing spondylitis underwent arthroplasty 15 years ago.

CONCLUSIONS

The neoplastic process may be considered as an extraordinary complication of THA and might just be coincidental or the result of some derangement of the healing process in host tissue with no definitely proven hypothesis that the implants or their by-products are carcinogenic. The soluble chemical substances from the implanted prosthetic material are, at least in animals, suspected to play a vital role in the pathogenesis of the neoplastic transformation of the bone tissue. The presented case shall alert orthopedic surgeons to clinical, radiologic, and macroscopic similarities between a malignant tumor and benign lesions caused by wear debris at THA sites. At the examination of plane X-rays of patients with THA loosening, the differential diagnosis should always include osteogenic sarcoma, as well. To our knowledge, there have been only nine cases of THA-related osteogenic osteosarcomas described in the English-language literature.

Long-term Local and Systemic Safety of Poly(l-lactide-co-epsilon-caprolactone) after Subcutaneous and Intra-articular Implantation in Rats

The use of biodegradable materials is gaining popularity in medicine, especially in orthopedic applications. However, preclinical evaluation of biodegradable materials can be challenging, since they are located in close contact with host tissues and might be implanted for a long period of time. Evaluation of these compounds requires biodegradability and biocompatibility studies and meticulous pathology examination. We describe 2 preclinical studies performed on Sprague-Dawley rats for 52 weeks, to evaluate clinical pathology, biocompatibility, biodegradability, and systemic toxicity after implantation of 2-layered films or saline-inflated balloon-shaped implants of downsized InSpace™ devices (termed “test device”). The test devices are made from a copolymer of poly-l-lactide-co-∊-caprolactone in a 70:30 ratio, identical to the device used in humans, intended for the treatment of rotator cuff tears. Intra-articular film implantation and subcutaneous implantation of the downsized device showed favorable local and systemic tolerability. Although the implanted materials have no inherent toxic or tumorigenic properties, one animal developed a fibrosarcoma at the implantation site, an event that is associated with a rodent-predilection response where solid materials cause mesenchymal neoplasms. This effect is discussed in the context of biodegradable materials along with a detailed description of expected pathology for biodegradable materials in long-term rodent studies.

Establishment of a bioluminescence model for microenvironmentally induced oral carcinogenesis with implications for screening bioengineered scaffolds

Background

Microenvironmental cues play a major role in head and neck cancer. Biodegradable scaffolds used for bone regeneration might also act as stimulative cues for head and neck cancer. The purpose of this study was to establish an experimental model for precise and noninvasive evaluation of tumorigenic potential of microenvironmental cues in head and neck cancer.

Methods

Bioluminescence was chosen to image tumor formation. Early neoplastic oral keratinocyte (DOK) cells were luciferase‐transduced (DOK^Luc), then tested in nonobese diabetic severe combined immunodeficient IL2rγnull mice either orthotopically (tongue) or subcutaneously for their potential as “screening sensors” for diverse microenvironmental cues.

Results

Tumors formed after inoculation of DOK^Luc were monitored easier by bioluminescence, and bioluminescence was more sensitive in detecting differences between various microenvironmental cues when compared to manual measurements. Development of tumors from DOK^Luc grown on scaffolds was also successfully monitored noninvasively by bioluminescence.

Conclusion

The model presented here is a noninvasive and sensitive model for monitoring the impact of various microenvironmental cues on head and neck cancer in vivo. © 2015 The Authors Head & Neck Published by Wiley Periodicals, Inc. Head Neck38: E1177–E1187, 2016

Differential Contribution of Acute and Chronic Inflammation to the Development of Murine Mammary 4T1 Tumors

Based on the notion that inflammation favors tumorigenesis, our experiments comparatively assessed the influence of acute and chronic inflammation on the development of a murine mammary tumor (4T1). In addition, we characterized angiogenic and inflammatory markers in the tumor tissue and systemically. Subcutaneous implantation of polyether-polyurethane sponge discs in Balb/c mice was used to host 4T1 tumor cells (1x10(6)), which were inoculated intraimplant 24 h or 10 days post implantation. Flow cytometric analysis of enzyme-digested implants revealed that, after 24 hours, the population of leukocytes was primarily characterized by neutrophils (42.53% +/- 8.45) and monocytes (37.53% +/- 7.48), with some lymphocytes (16.27% +/- 4.0) and a few dendritic cells (1.82% +/- 0.36). At 10 days, macrophages were predominant (37.10% +/- 4.54), followed by lymphocytes (28.1% +/- 4.77), and monocytes (22.33% +/- 3.05), with some dendritic cells (13.60% +/- 0.55) and neutrophils (11.07% +/- 2.27). A mammary tumor grown in a chronic inflammatory environment was 2-fold when compared with one grown in acute inflammation and 5-fold when compared with tumor alone. The levels of pro-angiogenic cytokine (VEGF-Vascular Endothelial Growth Factor) were higher in implant-bearing tumor when 4T1 cells were grown in 10-day old implants as compared to the VEGF levels of the two other groups. Overall, the levels of the inflammatory markers evaluated (NAG -N-acetylglucosaminidase, TNF-α-Tumor Necrosis Factor-α) were higher in both groups of implant-bearing tumors and in serum from those animals when compared with the tumor alone levels. This inflammation-related difference in tumor growth may provide new insights into the contribution of different inflammatory cell populations to cancer progression.

Silicone Implants with Smooth Surfaces Induce Thinner but Denser Fibrotic Capsules Compared to Those with Textured Surfaces in a Rodent Model

Purpose

Capsular contracture is the most frequent long-term complication after implant-based breast reconstruction or augmentation. The aim of this study was to evaluate the impact of implant surface properties on fibrotic capsule formation in an animal model.

Materials and Methods

Twenty-four rats received 1 scaled down silicone implant each; 12 of the rats received implants with textured surfaces, and the other 12 received implants with smooth surfaces. After 60 and 120 days, rats in each group underwent 7-Tesla Magnetic Resonance Imaging (MRI) and high-resolution ultrasound (HR-US), and specimens of the capsules were acquired and used to measure capsule thickness through histology, collagen density through picro sirius red staining, and analyses of expression of pro-fibrotic and inflammatory genes (Collagen1-4, TGFb1, TGFb3, Smad3, IL4, IL10, IL13, CD68) through qRT-PCR. Furthermore, MRI data were processed to obtain capsule volume and implant surface area.

Results

On day 60, histology and HR-US showed that fibrotic capsules were significantly thicker in the textured implant group with respect to the smooth implant group (p<0.05). However, this difference did not persist on day 120 (p=0.56). Capsule thickness decreased significantly over the study period in both smooth and textured implant groups (p<0.05). Thickness measurements were substantiated by MRI analysis and volumes changed accordingly. Implant surface area did not vary between study dates, but it was different between implant types. On day 60, the density of collagen in the fibrotic capsules was significantly lower in the textured implant group with respect to the smooth group (p<0.05), but again this difference did not persist on day 120 (p=0.67). Collagen 1 and CD68 were respectively over- and under expressed in the textured implant group on day 60. Significant differences in the expression of other genes were not observed.

Conclusion

Silicone implants with textured surfaces led to temporarily thicker but less dense fibrotic capsules compared with smooth surfaces. 7-Tesla MRI and HR-US are capable for non-invasive in-vivo assessment of capsular fibrosis in an animal model and can provide unique insights into the fibrotic process by 3D reconstruction and surface area measurement.

Anaplastic large cell lymphoma occurring in women with breast implants: analysis of 173 cases

BACKGROUND

The first silicone breast implant was inserted in 1962. In 1997, the first case of anaplastic large cell lymphoma (ALCL) in association with a silicone breast implant was reported. The authors reviewed 37 articles in the world literature reporting on 79 patients and collected another 94 unreported cases as of the date of submission.

METHODS

The world literature was reviewed. Missing clinical and laboratory information was solicited from the authors and treating physicians. As several different specialties were involved, information was not in one place. Many (but not all) authors and treating physicians were responsive, resulting in incomplete data.

RESULTS

ALCL lesions first presented as late peri-implant seromas, a mass attached to the capsule, tumor erosion through the skin, in a regional node, or discovered during revision surgery. The clinical course varied widely from a single positive cytology result followed by apparent spontaneous resolution, to disseminated treatment-resistant tumor and death. There was no preference for saline or silicone fill or for cosmetic or reconstructive indications. Where implant history was known, the patient had received at least one textured-surface device. Extracapsular dissemination occurred in 18 cases; nine of those were fatal. Histochemical markers were primarily CD-30 and Alk-1. Other markers occurred at a lower frequency. Risk estimates ranged from one in 500,000 to one in 3 million women with implants.

CONCLUSION

Breast implant-associated ALCL is a novel manifestation of site- and material-specific lymphoma originating in a specific scar location, presenting a wide array of diverse characteristics and suggesting a multifactorial cause.

Breast implant-associated anaplastic large cell lymphoma: a case report and literature review

Breast implant-associated anaplastic large cell lymphoma (ALCL) is a rare new clinical entity. The incidence is 0.3 % per 100,000 women per year. Patients present with non-specific implant-related complications resulting in delayed diagnosis. We present such a case to raise awareness and discuss management. A 48-year-old female presented with a 3-month history of left breast pain and swelling. She had undergone multiple bilateral augmentations 8 years previously. Triple assessment revealed a seroma, and a magnetic resonance imaging scan excluded implant rupture. Cytology showed a typical cells with mitotic activity which lead to removal of implants and a left capsulectomy. Final histology revealed an anaplastic lymphoma kinase (ALK) negative ALCL confined to the capsule. A computerised tomography scan and bone marrow biopsy excluded systemic disease, but due to later identified B symptoms, she received CHOP chemotherapy under the care of the haematologists. ALK-negative ALCL is associated with breast implants, and any persistent late onset seroma or breast symptoms should raise the suspicion of ALK-negative ALCL as a differential diagnosis. The recommended treatment is surgical removal of the implant including a full capsulectomy, highlighting the suspicion of ALCL to the pathologist. Exclusion of systematic disease is also recommended in all patients, and the need for adjuvant therapy should be addressed on an individual case basis. For disease confined to the capsule, adjuvant chemoradiotherapy is not needed.

LEVEL OF EVIDENCE V

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Polypropylene mesh: evidence for lack of carcinogenicity

Tumors related to the implantation of surgical grade polypropylene in humans have never been reported. In this commentary we present a balanced review of the information on what is known regarding the host response to polypropylene and provide data as to why the potential for carcinogenicity of polypropylene mesh is exceedingly small.

Selection of appropriate tumour data sets for Benchmark Dose Modelling (BMD) and derivation of a Margin of Exposure (MoE) for substances that are genotoxic and carcinogenic: considerations of biological relevance of tumour type, data quality and uncertainty assessment

This article addresses a number of concepts related to the selection and modelling of carcinogenicity data for the calculation of a Margin of Exposure. It follows up on the recommendations put forward by the International Life Sciences Institute - European branch in 2010 on the application of the Margin of Exposure (MoE) approach to substances in food that are genotoxic and carcinogenic. The aims are to provide practical guidance on the relevance of animal tumour data for human carcinogenic hazard assessment, appropriate selection of tumour data for Benchmark Dose Modelling, and approaches for dealing with the uncertainty associated with the selection of data for modelling and, consequently, the derived Point of Departure (PoD) used to calculate the MoE. Although the concepts outlined in this article are interrelated, the background expertise needed to address each topic varies. For instance, the expertise needed to make a judgement on biological relevance of a specific tumour type is clearly different to that needed to determine the statistical uncertainty around the data used for modelling a benchmark dose. As such, each topic is dealt with separately to allow those with specialised knowledge to target key areas of guidance and provide a more in-depth discussion on each subject for those new to the concept of the Margin of Exposure approach.

Proliferative and non-proliferative lesions of the rat and mouse soft tissue, skeletal muscle and mesothelium

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP), and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying lesions observed in the soft tissues including skeletal muscle as well as the mesothelium of rats and mice. The standardized nomenclature of lesions presented in this document is also available electronically on the Internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous developmental and aging lesions as well as those induced by exposure to test materials. A widely accepted and utilized international harmonization of nomenclature for lesions in soft tissues, skeletal muscle and mesothelium in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists. (DOI: 10.1293/tox.26.1S; J Toxicol Pathol 2013; 26: 1S-26S).

Corrosion at the cone/taper interface leads to failure of large-diameter metal-on-metal total hip arthroplasties

BACKGROUND

Metal-on-metal (MoM) THAs have reduced wear rates compared with metal-on-polyethylene. However, elevated serum metal ion levels and pseudotumors have been reported in large MoM articulations.

QUESTIONS/PURPOSES

We therefore determined (1) if corrosion occurred at the cone/taper interface leading to instability in patients with large-diameter THAs; (2) how patients presented clinically and radiographically; (3) if adverse periprosthetic tissue reactions occurred; (4) whether metal was released from the implants into the periprosthetic tissues; and (5) if head size correlated with metal release.

METHODS

We reviewed 114 patients who had revisions of large-diameter head MoM articulations. Mean time of implantation was 46 months. To identify adverse reactions and particle load, tissues were stained by hematoxylin and eosin and CD3/CD20/CD68 antibodies. Periprosthetic tissues were analyzed for metal content and distribution in different regions. Electrochemical reactions between the stem and adapter were investigated by a minicell electrode.

RESULTS

Electrochemical studies on the stem and the head adapter showed a risk for galvanic corrosion. Ninety-four percent of patients had instability at the cone/taper interface. All patients presented with early clinical symptoms; 59 patients had radiographic signs of loosening. One hundred four patients had foreign body reactions and necrosis. The largest amounts of metal released were titanium or iron. We found no correlation between head size and metal ion release.

CONCLUSIONS

These findings suggest that in modular cone/taper connections, friction of the MoM articulations may cause failure of the cone/taper interface leading to galvanic corrosion and loosening. It is unclear whether the design of this MoM system provides sufficient stability at the taper.

Spontaneous fibrosarcoma in an experimental aged Lewis rat

This case report describes the results of the gross pathological, histological and immunohistological examinations of a fibrosarcoma that spontaneously developed in the left neck region of an aged male Lewis rat that participated in a long-term facial nerve regeneration study. A 10 mm long polylactic acid (PLA) tube was implanted into a 7 mm critical defect gap of the buccal branch of the left facial nerve of a male eight-week-old Lewis rat. Forty-two weeks after implantation, an approximately 8 cm × 9 cm × 2.5 cm rapidly growing mass with ulceration of the overlying skin was found in the left neck region. Gross examination of the tumour and the surrounding tissues before tumour excision revealed that the tumour had clear boundaries, and had not invaded any facial tissues, the facial nerve and the PLA nerve guide. Gross examination of the tumour's cut surface revealed that the tumour comprised numerous smooth nodules with a homogeneous white tan colour. Examination of the haematoxylin and eosin-stained sections of the tumour revealed that the tumour was predominantly composed of bundles of spindle-shaped atypical proliferating cells that were mixed with bundles of collagen fibres and arranged in a storiform pattern. Tumour emboli and skin invasion were also observed. Immunohistological examination revealed that the tumour cells were weakly positive for vimentin, but negative for keratin, α-smooth muscle actin, S-100 protein and CD34. From the results of these analyses, the final pathological diagnosis of this tumour was a fibrosarcoma.

Local and systemic toxicity of nanoscale debris particles in total hip arthroplasty

Over the past 30 years joint replacement prostheses have been developed and refined to enhance durability and reproducibility. Total hip joint arthroplasty is being performed in an increasing number of younger patients; therefore orthopaedic surgeons seek implants with a longer life span. With regards to the progress of mechanical behaviour of the biomaterials used in an arthroplasty, little is known about the long-term biological effects of wear debris. Owing to the composition of the prostheses currently in use, systemic exposure to chromium (Cr), cobalt (Co), nickel (Ni) and aluminium (Al) alloys occurs as a result of the formation of metal wear nano-particles that are released both from metal-on-metal and polyethylene-on-metal bearings, resulting in a postoperative increase in metal ion levels at different organ sites. These particles circulate both locally and systemically, penetrate cell plasma membranes, bind to cellular proteins and enzymes and modulate cytokine expression. Their physiologic effects are poorly understood and their potential toxicity, hypersensitivity and carcinogenicity remain a cause for concern. In this article we will address the issue of whether these nanoscale degradation products are associated with adverse, clinically significant local or systemic toxicologic sequelae.

Malignant fibrous histiocytoma at the site of an alumina-on-alumina-bearing total hip arthroplasty mimicking infected trochanteric bursitis

Although the incidence of malignant tumors in patients undergoing total hip arthroplasties (THAs) is known to be lower than the general population, there exist several reports on the development of malignant tumors at the site of THAs. We report another case of malignant fibrous histiocytoma at the site of a THA, which was developed in an older patient who presented a cystic mass around the total hip prosthesis using a ceramic-on-ceramic bearing system, even without evidence of osteolysis or loosening of implants. This is the second case associated with an aluminum oxide prosthesis in English literature.

Peritoneal sarcomatosis associated with telemetry implants in Sprague Dawley CD rats: a review of eight cases

Surgical implantation of radiotelemetric transmitters is a current practice to collect a variety of physiological parameters in unrestrained laboratory animals, and in rodents in particular. In this study, the incidence of peritoneal sarcomatosis arising secondary to surgically implanted telemetry devices (< 15% of implanted Sprague Dawley rats) is considered to represent a significant issue for both animal welfare and data validity in affected animals. Macroscopically, the telemetry-associated fibrosarcomas spread along the visceral and parietal peritoneum and mesentery surrounding abdominal organs. The histologic morphology of these sarcomas was typically an undifferentiated sarcoma, although well-differentiated fibrosarcomas and telangiectatic and pleomorphic variants were noted. Using special stains such as Masson's Trichrome demonstrated a collagenous extracellular matrix in 50% of these rats, which is consistent with a fibroblastic origin. Immunohistochemical studies clearly delineated the mesenchymal components of the sarcomas (fibroblasts and smooth muscle cells); one case, however, was diagnosed as an osteosarcoma.

Biological interactions of graphene-family nanomaterials: an interdisciplinary review

Graphene is a single-atom thick, two-dimensional sheet of hexagonally arranged carbon atoms isolated from its three-dimensional parent material, graphite. Related materials include few-layer-graphene (FLG), ultrathin graphite, graphene oxide (GO), reduced graphene oxide (rGO), and graphene nanosheets (GNS). This review proposes a systematic nomenclature for this set of Graphene-Family Nanomaterials (GFNs) and discusses specific materials properties relevant for biomolecular and cellular interactions. We discuss several unique modes of interaction between GFNs and nucleic acids, lipid bilayers, and conjugated small molecule drugs and dyes. Some GFNs are produced as dry powders using thermal exfoliation, and in these cases, inhalation is a likely route of human exposure. Some GFNs have aerodynamic sizes that can lead to inhalation and substantial deposition in the human respiratory tract, which may impair lung defense and clearance leading to the formation of granulomas and lung fibrosis. The limited literature on in vitro toxicity suggests that GFNs can be either benign or toxic to cells, and it is hypothesized that the biological response will vary across the material family depending on layer number, lateral size, stiffness, hydrophobicity, surface functionalization, and dose. Generation of reactive oxygen species (ROS) in target cells is a potential mechanism for toxicity, although the extremely high hydrophobic surface area of some GFNs may also lead to significant interactions with membrane lipids leading to direct physical toxicity or adsorption of biological molecules leading to indirect toxicity. Limited in vivo studies demonstrate systemic biodistribution and biopersistence of GFNs following intravenous delivery. Similar to other smooth, continuous, biopersistent implants or foreign bodies, GFNs have the potential to induce foreign body tumors. Long-term adverse health impacts must be considered in the design of GFNs for drug delivery, tissue engineering, and fluorescence-based biomolecular sensing. Future research is needed to explore fundamental biological responses to GFNs including systematic assessment of the physical and chemical material properties related to toxicity. Complete materials characterization and mechanistic toxicity studies are essential for safer design and manufacturing of GFNs in order to optimize biological applications with minimal risks for environmental health and safety.

A sarcoma at the site of previous extravasation of adriamycin

We report the case of a 66-year-old man presenting with a high-grade pleomorphic sarcoma at the left elbow 16 years after the extravasation of adriamycin given for a malignant ifbrous histiocytoma of the tibia.We suggest that this sarcoma originated in a multistep way over many years, out of the chronic inflammatory tissue that developed due to a non-specific cellular damage at the nuclear level, interfering with normal cell replication necessary for normal healing tissue healing. As a result, the non-healed chronic inflammatory tissue transformed over several years into a preneoplastic mesenchymal tumour and later into a high-grade pleomorphic sarcoma.

Parinaric acid methyl ester polymer films with hill-structured features: fabrication and different sensitivities to normal and tumor cells

Parinaric acid methyl ester (PnA-Me) polymer films with hill-structured features were fabricated by a solvent volatilization in situ cross-linking method. Moreover, nuclear magnetic resonance, Fourier transform infrared, and oxidation kinetic analyses were successfully applied to monitor the formation process of PnA-Me polymer films. The role of PnA-Me monomer concentrations for growth control of the hill structures on a glass matrix had also been investigated. Also, the results demonstrated that size control of the resulting hill structure ranging from 0.56 ± 0.18 to 19.6 ± 3.5 μm could be realized by varying the concentration of the PnA-Me monomer from 0.0117 to 1.5 mg/mL. Additionally, the effects of polymer films with different surface topographical structures on the behaviors of rat mesenchymal stem cells and human pheochromocytoma cells were measured by morphological and metabolic methods. The results revealed that the cell activity of PnA-Me films was topographical structure- and cell-type-dependent. Furthermore, the selective sensitivity of the PnA-Me films to normal and tumor cells supported the potential value as the coatings for the tissue engineering substitutes.

Severe osteolysis and soft tissue mass around total hip arthroplasty: description of four cases and review of the literature with respect to clinico-radiographic and pathologic differential diagnosis

Periprosthetic osteolysis is a well known phenomenon caused by wear particle-induced bone resorption, particularly common and extensively reported in total hip arthroplasty. Its typical radiographic feature is a radiolucent area adjacent to an implant, sometimes associated with a soft tissue mass. Osteolytic changes may be caused by numerous other pathologic processes, including infection, metabolic disease, and neoplasia. Four cases of massive periprosthetic bone destruction associated with a large soft tissue mass around a failed total hip replacement are presented. In three cases, a diagnosis of periprosthetic osteolysis was correctly made and managed by revision surgery. However, in one case angiosarcoma of the ipsilateral hemipelvis went long unrecognized despite aggressive clinical course, requiring hind-quarter amputation and ultimately resulting in the patient's death. Periprosthetic malignancy in the form of either primary sarcoma or metastatic cancer is a very rare yet reported event in the setting of previous hip replacement, likely leading to catastrophic consequences when diagnosis is not established in a timely manner. The differential diagnosis of periprosthetic osteolysis should consider the entire spectrum of conditions that can present with radiolucent changes. Thorough review of patient's history and course of symptoms, along with careful evaluation of standard roentgenograms should be always performed and possibly integrated with imaging modalities such as CT, MRI, and bone scintigraphy in order to increase diagnostic accuracy. If uncertainty remains, biopsy should always be considered to rule out malignancy.

Molecular and cellular biology of rhabdomyosarcoma

Rhabdomyosarcoma is a group of soft-tissue sarcomas that share features of skeletal myogenesis, but show extensive heterogeneity in histology, age and site of onset, and prognosis. This review matches recent molecular data with biological features of rhabdomyosarcoma. Alterations in molecular pathways, animal models, cell of origin and potential new therapeutic targets are discussed.

[Classification of prosthetic loosening and determination of wear particles]

Nowaday, loosening of orthopaedic implants implies important medical and socioeconomic problems. Implant loosening is caused by implant infections as well as aseptic loosening, due to particle disease and mechanical alterations. Clinically we divide the implant infection into early and late infections. Morphologically it is possible to reliably detect the infection by quantification of neutrophil granulocytes. Additionally molecular methods are suitable to detect micro-organisms which are responsible for the prosthetic joint infection including their resistance to antibiotics. Particle disease may be reproducibly classified by the detection of different types of wear particles, particularly polyethylene, metal, ceramic and cement. The aetiology of the indeterminate type of the periprosthetic membrane is obscure, but may be associated with osteopathies. This classification of the periprosthetic membrane morphology provides clinically significant information concerning clinical management of implant loosening.

Recurrence of a laryngeal spindle cell sarcoma with a transformation into a higher grade of malignancy

Primary malignant mesenchymal neoplasms of the larynx are rare. Sarcomas of the larynx account for <1% of all malignant laryngeal mesenchymal neoplasms. This report examines a case of a recurring laryngeal, initial benign-appearing mesenchymal tumour, which first changed its clinical phenotype without any histological signs of malignancy and later also its histological appearance with signs of malignancy. Finally, it even underwent a transformation into a higher grade of malignancy. In addition to this, the difficulties of allocating this tumour to the correct sarcoma subentity are shown.

Biomaterial-induced sarcomagenesis is not associated with microsatellite instability

Sarcomagenesis, in contrast to carcinogenesis, is poorly understood. Microsatellite instability has been implicated in the development of many cancers, in particular those associated with chronic inflammatory conditions. In an experimental animal model, rats developed not only a peri-implantational chronic inflammatory reaction, but also malignant mesenchymal tumors in response to different biomaterials. Therefore, it was the aim of our study to test if the development of biomaterial-induced sarcomas is characterized by a mutator phenotype. A multiplex-PCR approach was designed to screen biomaterial-induced sarcomas for the presence of microsatellite instability. Seven different microsatellite loci were tested in ten tumors for microsatellite instability using a fluorochrome-labelled multiplex-PCR and subsequent fragment analysis. All tumors provided a microsatellite-stable phenotype at all loci tested. Our data suggest that microsatellite instability is rarely or not at all a feature of malignant transformation of biomaterial-induced soft tissue tumors. Thus, there is no evidence that a mutator phenotype is a hallmark of biomaterial-induced sarcomagenesis.

Use of rasH2 transgenic mice for carcinogenesis testing of medical implants

Several transgenic mice models are accepted by regulatory agencies to determine the carcinogenic potential and predict the human response to exposure of chemicals, as an alternative to the conventional 2-year rodent bioassay. The rasH2 transgenic mouse model has been proposed to evaluate the carcinogenic potential of medical devices, but few data are currently available regarding study design--namely appropriate positive and negative controls to be used--as well as historical pathology data. BIOMATECH-NAMSA recently conducted a 26-week carcinogenicity study following subcutaneous implantation in the transgenic rasH2 mouse model. This paper describes the study design and the main results obtained in the positive and negative control groups. The survival rate statistical (Kaplan-Meier) analysis showed that the survival rate was significantly affected by the occurrence of tumors in the positive control group when compared to the negative control group, in both genders. Thymic malignant lymphomas and squamous cell papillomas were reported to occur at a higher incidence in rasH2 mice exposed to a known chemical carcinogen, for terminally sacrificed animals as well as for unscheduled and terminally sacrificed animals considered together. Background and age-related lesions were few. Taken together, these data confirmed the reliability and usefulness of the rasH2 transgenic model in the assessment of carcinogenic properties of medical devices. A major beneficial property of this animal model consisted in the ability to demonstrate chemical carcinogenesis response without the solid-state tumorigenesis response seen in traditional 2-year rodent bioassays.

[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.