Pigmented villonodular synovitis: current concepts about diagnosis and management

Patient-Reported Outcomes after Surgery for Pigmented Villonodular Synovitis in the Knee: A Cohort Study

Pigmented villonodular synovitis (PVNS) is a rare neoplastic proliferation of large joints, including the knee, with both localized PVNS (LPVNS) and diffuse PVNS (DPVNS) types. DPVNS is known to recur at a higher rate following resection; however, there is little evidence comparing patient-reported outcomes (PROs) between the two types. The purpose of this study was to compare PROs between patients with LPVNS and DPVNS involving the knee 2 years after surgical resection. We hypothesized that DPVNS would have worse 2-year PROs than LPVNS.Sixteen patients who underwent arthroscopic resection of pathology-confirmed PVNS involving the knee were enrolled in a prospective registry. Several PROs, including six Patient-Reported Outcomes Measurement Information System (PROMIS) domains and the International Knee Documentation Committee (IKDC) Subjective Knee Form, were assessed at baseline and at 2 years postoperatively. Mean scores between LPVNS and DPVNS groups were compared using a Wilcoxon exact test, while categorical variables were compared using a Fisher's exact test.Eleven patients (seven LPVNS and four DPVNS) completed both the baseline and 2-year PRO surveys. There were no significant differences in the demographic variables between groups, including age, body mass index, or prior surgical history (p < 0.05). There was a trend toward higher mean PRO scores in the DPVNS group at 2 years postoperatively in all measures, despite lower reported baseline levels of activity as measured by Marx Activity Rating Scale (26.3 vs. 76.7, p = 0.02). The DPVNS group also trended toward more improvement in PROMIS Physical Function (9.7 vs. -2.7), PROMIS Pain Interference (-9.0 vs. -2.5), PROMIS Anxiety (-5.4 vs. -4.4), and IKDC (26.7 vs. 18.9). However, these differences did not reach statistical significance (p < 0.05). There were two recurrences in the DPVNS group and none in the LPVNS group.Patients with knee DPVNS do not report worse outcomes 2 years after arthroscopic resection compared with LPVNS patients.

Recurrence of arthroscopic treatment of pigmented villonodular synovitis of the knee: A systematic review and meta-analysis

Purpose

The purpose of this study was to assess the efficacy of arthroscopic intervention on the treatment of pigmented villonodular synovitis (PVNS) patients, with a focus on the potential advantages of this approach in lowering the risk of disease recurrence.

Methods

We performed a systematic review and meta-analysis following the PRISMA 2020 protocol. Our search encompassed five databases, namely PubMed, Embase, Scopus, Web of Science and Cochrane Library. Statistical analysis was conducted on the extracted data by using the R ver. 4.4.0 software. This study included English-language observational studies (case series and cohort studies) published up to 31 March 2024, focusing on in vivo human subjects with at least 2 years of follow-up. Studies with less than 2 years of follow-up, non-arthroscopic treatment methods or addressing PVNS in structures other than the knee were excluded.

Results

We identified 24 articles, comprising 7 case series and 17 cohort studies, based on title, abstract, and quality assessments. Approximately 16% (95% confidence interval [CI]: 10.4%-24.75%) of knees that underwent arthroscopic surgery were found to be at risk of recurrence. In line with our expectations, sub-group analysis comparing recurrence rates among different subtypes of PVNS found that the diffuse subtype exhibited a higher recurrence rate of 19.4% (95% CI: 10.01%-34.15%), compared to the local subtype, which had a recurrence rate of 9.5% (95% CI: 4.47%-19.01%). Based on the meta-regression analysis, no significant association was found between the recurrence rate and the publication year or patient mean age. However, there was a noticeable rise in the recurrence rate with a longer follow-up period, indicating a probable correlation between extended follow-up and increased recurrence rates.

Conclusion

Our findings suggest that arthroscopic surgery for PVNS, particularly for the diffuse subtype, results in a higher recurrence rate compared to the localized subtype. However, the inherent challenges in achieving complete resection through arthroscopy, particularly in cases with extensive disease involvement, may contribute to the observed recurrence rates.

Level of Evidence

Level III systematic review and meta-analysis.

Pexidartinib Upfront in a Case of Tenosynovial Giant Cell Tumor: Proof of Concept for a Treatment Paradigm Shift

BACKGROUND

Tenosynovial giant cell tumor (TGCT) is a rare, locally aggressive tumor of the joints, bursa, and tendon sheath that can cause considerable pain and substantial morbidity. Although surgery is the primary treatment for patients with TGCT, surgical resection is associated with high rates of recurrence, particularly for patients with diffuse TGCT. Pexidartinib, a colony-stimulating factor 1 receptor inhibitor, is approved by the US Food and Drug Administration for the treatment of adult patients with symptomatic TGCT associated with severe morbidity or functional limitations and not amenable to improvement with surgery.

CASE DESCRIPTION

A 32-year-old man presented with intra-articular diffuse TGCT with pain and received noncurative treatment for 5 years (2014-2019). In 2019, the patient was found to have extensive disease accompanied by pain and limited range of motion. The patient's case was presented to a sarcoma multidisciplinary tumor board, who determined that surgery would cause significant morbidity and macroscopic residual tumor. As a result of the extent of disease, young age, and otherwise good health, treatment with pexidartinib was started through a compassionate use program at 800 mg/day. After dose reductions to pexidartinib at 400 mg/day and then 200 mg/day as a result of creatine phosphokinase elevations, the patient achieved a complete response after 2 years of treatment; pain was reduced and mobility was restored. The patient reported no side effects related to pexidartinib treatment. Treatment was stopped in 2022 for future family planning. After pexidartinib therapy was interrupted, the patient's wife had a successful pregnancy and delivery; however, the disease showed a slow but constant clinical deterioration, with a reduction in the range of movement of the affected knee and an apparent increase in widespread TGCT nodules.

CONCLUSION

Our case is unique because it provides support for pexidartinib use as upfront therapy for TGCT, instead of surgery, in selected cases.

Can Primary Knee Tuberculosis Simulate the Clinical and Radiological Profile of Pigmented Villonodular Synovitis?

When faced with clinical and radiological findings suggestive of villonodular synovitis, tuberculosis is not often considered a differential diagnosis, especially when the patient is not a known tuberculosis carrier. In this paper, we present an exceptional case of a patient who had a tumefaction (measuring 17 cm in length) in the anterointernal region of her left knee, with a clinical and radiological picture in favor of villonodular synovitis. However, after tumor resection, the anatomopathological study of the surgical specimen came back in favor of a tuberculous lesion. This exceptional case shows that tuberculosis should be retained as a diagnostic possibility in the presence of clinical and radiological findings in favor of villonodular synovitis, even if the patient is not known to have a tuberculous lesion elsewhere.

Case report: Tenosynovial giant cell tumor

Tenosynovial giant cell tumor (TGCT) is a rare type of tumor that originates from the synovium of joints and tendon sheaths. It is characterized by recurring genetic abnormalities, often involving the CSF1 gene. Common symptoms include pain and swelling, which are not specific to TGCT, so MRI and a pathological biopsy are needed for an accurate diagnosis. We report the case of a 45-year-old man who experienced painful swelling in his right hip for six months. Initially, this was diagnosed as Erdheim-Chester disease. However, whole exome sequencing (WES) and RNA-Sequencing revealed a CSF1::GAPDHP64 fusion, leading to a revised diagnosis of TGCT. The patient was treated with pegylated interferon and imatinib, which resulted in stable disease after three months. Single-cell transcriptome analysis identified seven distinct cell clusters, revealing that neoplastic cells expressing CSF1 attract macrophages. Analysis of ligand-receptor interactions showed significant communication between neoplastic cells and macrophages mediated by CSF1 and CSF1R. Our findings emphasize the importance of comprehensive molecular analysis in diagnosing and treating rare malignancies like TGCT.

Total knee arthroplasty in pigmented villonodular synovitis osteoarthritis: a systematic review of literature

PURPOSE

Pigmented Villonodular Synovitis (PVNS) is a proliferative disease arising from the synovial membrane, mainly affects large joints such as the knee (almost 80% of total). Prostheses implanted in PVNS osteoarthritis show a higher revision rate when compared to primary osteoarthritis, due to the recurrence of disease and the overall surgical complications. The purpose of this systematic review is to summarize and compare indications, clinical and functional outcomes, disease-related and surgical-related complications of total knee arthroplasty in PVNS osteoarthritis.

MATERIALS AND METHODS

A systematic review of the literature was performed with a primary search on Medline through PubMed. The PRISMA 2009 flowchart and checklist were used to edit the review. Screened studies had to provide preoperative diagnosis, previous treatments, main treatment, concomitant strategies, mean follow-up, outcomes and complications to be included in the review.

RESULTS

A total of 8 articles were finally included. Most of papers reported the use of non-constrained design implants, mainly posterior stabilized (PS) and in case of PVNS with extensive joint involvement implants with higher degree of constraint to obtain a fulfilling balancing. Recurrence of PVNS has been indicated as the major complication, followed by aseptic loosening of the implant and difficult post-operative course with an increased risk of stiffness.

CONCLUSION

Total knee arthroplasty represents a valid treatment for patients with PVNS end-stage osteoarthritis, with good clinical and functional results, even in longer follow-up. It would be advisable a multidisciplinary management and a meticulous rehabilitation and monitoring following the procedure, to reduce the emergence of recurrence and overall complications.

Pigmented villonodular synovitis and rheumatoid arthritis: diagnostic challenges and therapeutic considerations in a case of knee pain

We present a case of a woman in her 30s who visited the rheumatology clinic due to her persistent knee pain for 5 years, which spread to multiple joints. She was diagnosed with seropositive rheumatoid arthritis (RA). While most joints responded well to methotrexate and subsequently etanercept, persistent unilateral knee pain prompted further investigation. Imaging revealed synovitis and joint effusion in her knee, prompting arthroscopy and synovial biopsy, revealing pigmented villonodular synovitis (PVNS). Despite initial success with a tricompartmental synovectomy, her disease recurred. The decision was made to pursue medical therapy, with pexidartinib initiated by the oncology team. Our case report highlights the importance of considering other underlying conditions in patients with RA who do not achieve full clinical improvement despite standard treatment. Physicians should remain vigilant for atypical presentations and imaging features in patients with RA, for early recognition of PVNS can significantly impact treatment decisions and patient outcomes.

Real-world drug utilization and treatment patterns in patients with tenosynovial giant cell tumors in the USA

Aim: Real-world treatment patterns in tenosynovial giant cell tumor (TGCT) patients remain unknown. Pexidartinib is the only US FDA-approved treatment for TGCT associated with severe morbidity or functional limitations and not amenable to improvement with surgery. Objective: To characterize drug utilization and treatment patterns in TGCT patients. Methods: In a retrospective observational study using IQVIA's linked prescription and medical claims databases (2018-2021), TGCT patients were stratified by their earliest systemic therapy claim (pexidartinib [N = 82] or non-FDA-approved systemic therapy [N = 263]). Results: TGCT patients treated with pexidartinib versus non-FDA-approved systemic therapies were predominantly female (61 vs 50.6%) and their median age was 47 and 54 years, respectively. Pexidartinib-treated patients had the highest 12-month probability of remaining on treatment (54%); 34.1% of pexidartinib users had dose reduction after their first claim. Conclusion: This study provides new insights into the unmet need, utilization and treatment patterns of systemic therapies for the treatment of TGCT patients.

Identification of potential diagnostic biomarkers for tenosynovial giant cell tumour by integrating microarray and single-cell RNA sequencing data

PURPOSE

Tenosynovial giant cell tumour (TGCT) is a benign hyperplastic and inflammatory disease of the joint synovium or tendon sheaths, which may be misdiagnosed due to its atypical symptoms and imaging features. We aimed to identify biomarkers with high sensitivity and specificity to aid in diagnosing TGCT.

METHODS

Two scRNA-seq datasets (GSE210750 and GSE152805) and two microarray datasets (GSE3698 and GSE175626) were downloaded from the Gene Expression Omnibus (GEO) database. By integrating the scRNA-seq datasets, we discovered that the osteoclasts are abundant in TGCT in contrast to the control. The single-sample gene set enrichment analysis (ssGSEA) further validated this discovery. Differentially expressed genes (DEGs) of the GSE3698 dataset were screened and the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of DEGs were conducted. Osteoclast-specific up-regulated genes (OCSURGs) were identified by intersecting the osteoclast marker genes in the scRNA-seq and the up-regulated DEGs in the microarray and by the least absolute shrinkage and selection operator (LASSO) regression algorithm. The expression levels of OCSURGs were validated by an external dataset GSE175626. Then, single gene GSEA, protein-protein interaction (PPI) network, and gene-drug network of OCSURGs were performed.

RESULT

22 seurat clusters were acquired and annotated into 10 cell types based on the scRNA-seq data. TGCT had a larger population of osteoclasts compared to the control. A total of 159 osteoclast marker genes and 104 DEGs (including 61 up-regulated genes and 43 down-regulated genes) were screened from the scRNA-seq analysis and the microarray analysis. Three OCSURGs (MMP9, SPP1, and TYROBP) were finally identified. The AUC of the ROC curve in the training and testing datasets suggested a favourable diagnostic capability. The PPI network results illustrated the protein-protein interaction of each OCSURG. Drugs that potentially target the OCSURGs were predicted by the DGIdb database.

CONCLUSION

MMP9, SPP1, and TYROBP were identified as osteoclast-specific up-regulated genes of the tenosynovial giant cell tumour via bioinformatic analysis, which had a reasonable diagnostic efficiency and served as potential drug targets.

A severe headache due to pigmented villonodular synovitis in a rare location: facial nerve on temporomandibular joint. A case report

BACKGROUND

Pigmented villonodular synovitis (PVNS) is an infrequent benign tumor-like proliferative lesion developing from the synovial membranes of the joint, tendon sheath, and bursa.

CLINICAL PRESENTATION

A 44-year-old woman with numbness on the right side of her face, severe headaches, and swelling in temporomandibular region is presented. On head and neck magnetic resonance imaging, an encapsulated mass approximately 2 cm was detected. The fine-needle aspiration biopsy resulted as suspicion of mesenchymal tumor. A complete resection with the capsule was performed over the temporal branch by monitoring of the facial nerve. The final histopathologic examination resulted as a giant cell tendon sheath tumor.

CONCLUSION

Headache is not the main symptom in PVNS, but in severe pain spreading from the temporomandibular region, physical examination should be done carefully for slight swelling, and the possibility of pigmented villonodular synovitis should be considered. Because of the high recurrence rate, en bloc resection is necessary.

MRI Prediction Model for Tenosynovial Giant Cell Tumor with Risk of Diffuse-type

RATIONALE AND OBJECTIVES

To propose a magnetic resonance imaging (MRI) prediction model for diffuse-type tenosynovial giant cell tumors (D-TSGCTs).

MATERIALS AND METHODS

Anatomic locations were classified and then nodularity, margin, peripheral and internal hypointensity, and bone and cartilage involvement were evaluated on MRI. Student's t-test, chi-square test, diagnostic performance, logistic regression analysis, and decision tree were performed.

RESULTS

Nineteen intra-articular (11 localized; eight diffuse) and 55 extra-articular (44 localized; 11 diffuse) TSGCTs were included. Extra-articular D-TSGCTs showed significantly more frequent multinodular (72.7% vs. 25.0%, p = 0.009), and infiltrative lesions (90.9% vs. 34.1%, p = 0.002), without peripheral hypointensity (90.9% vs. 18.2%, p < 0.001), and contained granular internal hypointensity (72.7% vs. 31.8%; p = 0.003) with more frequent bone (81.8% vs. 27.3%; p = 0.003) and cartilage (50.0% vs. 0.0%; p = 0.038) involvement than localized-type. Intra-articular D-TSGCT also showed significance in all MRI features (100.0% vs. 9.1%, p = 0.001; 100.0% vs. 27.3%, p = 0.007; 100.0% vs. 36.4%, p = 0.018; 100.0% vs. 27.3%, p = 0.007; 50.0% vs. 0.0%, p = 0.038), except bone involvement (37.5% vs. 9.1%, p = 0.352) than localized-type. Cartilage involvement revealed the highest specificity (88.6-100.0%), regardless of location. Nodularity (100.0%; odds-ratio [OR]: 70.000) and peripheral hypointensity (90.9%; OR: 62.250) demonstrated the highest sensitivities ORs for D-TSGCT in intra-articular and extra-articular cases, respectively. MRI models for D-TSGCG beginning with the cartilage involvement in both anatomic locations and next on nodularity and peripheral hypointensity in intra-articular and extra-articular locations, respectively, exhibited sensitivity and specificity of 100% and 90.9% for intra-articular and 100% and 77.2% for extra-articular TSGCTs, respectively.

CONCLUSION

MRI can suggest the risk of D-TSGCT by combining imaging features with anatomic locations.

Understanding the Effect of Osteoarthritis on Surgical Treatment Patterns, Healthcare Resource Utilization, and Costs Among Patients With Tenosynovial Giant Cell Tumors

BACKGROUND

Tenosynovial giant cell tumor (TGCT) may be misdiagnosed as osteoarthritis (OA), or the chronic course of TGCT may lead to development of secondary OA. However, little is known about the effect of comorbid OA on long-term surgical patterns and costs among TGCT patients.

METHODS

This cohort study used claims data from the Merative MarketScan Research Databases. The study included adults diagnosed with TGCT from January 1, 2014, to June 30, 2019, who have at least 3 years of continuous enrollment before and after the first TGCT diagnosis (date of the first TGCT diagnosis = index date) and no other cancer diagnosis during the study period. Patients were stratified by the presence of an OA diagnosis relative to the index date. Outcomes included surgical procedure patterns, healthcare resource utilization, and costs in the 3-year pre- and postindex periods. Multivariable models were used to assess the effect of OA on the study outcomes, controlling for baseline characteristics.

RESULTS

The study included 2856 TGCT patients: 1153 (40%) had no OA before or after index (OA[-/-]), 207 (7%) had OA before index but not after (OA[+/-]), 644 (23%) had OA after index but not before (OA[-/+]), and 852 (30%) had OA before and after index (OA[+/+]). The mean age was 51.6 years, and 61.7% were female. During the postperiod, joint surgery was more common among OA(-/+) and OA(+/+) patients compared with OA(-/-) and OA(+/-) patients (55.7% vs 33.2%). The mean all-cause total costs in the 3-year postperiod were $19,476 per patient per year. Compared with OA(-/-) patients, OA(-/+) and OA(+/+) patients had a higher risk of undergoing recurrent surgery and higher total healthcare costs postindex.

DISCUSSION

Higher rates of surgery and increased healthcare cost observed in TGCT patients with postindex OA underscore the need for effective treatment options to reduce joint damage, especially among patients with comorbid OA.

Tenosynovial giant cell tumors of digits: MRI differentiation between localized types and diffuse types with pathology correlation

OBJECTIVE

To compare the MRI findings between the localized- and diffuse-type tenosynovial giant cell tumors (TSGCTs) of digits with pathology correlation.

METHODS

Twenty-eight patients with newly diagnosed TSGCTs of digits (22 localized and 6 diffuse types) who underwent preoperative MRI and surgical excision were included from Jan. 2015 to September 2021. MRI findings regarding nodularity, margins, morphology of hypointensity with pathology correlation, and disease extent (bone erosion, articular involvement, muscle involvement, tendon destruction, and neurovascular encasement) were assessed.

RESULTS

Diffuse type was significantly larger (P = 0.006), more multinodular on both MRI and pathology (P = 0.038, both) with significant agreement, and infiltrative on both MRI and pathology (P < 0.001, both) with substantial agreement, and showed central granular on MRI and strong hemosiderin deposition on pathology (P = 0.022 and P = 0.021) with moderate agreement than localized type. Localized type showed significantly more frequent peripheral capsules on both MRI and pathology (P < 0.001, both) with moderate agreement than diffuse type. However, the septum on both MRI and pathology showed no statistically significant difference between the two groups (P = 0.529 and P = 0.372) without significant agreement. The disease extent was more severe in the diffuse type than the localized type regarding articular involvement (P < 0.001), muscle involvement (P < 0.001), and tendon destruction (P = 0.010). No statistically significant differences were found between the two groups regarding bone erosion (P = 0.196) or neurovascular bundle encasement (P = 0.165).

CONCLUSIONS

Diffuse-type TSGCTs of digits presented as locally aggressive lesions with larger, multinodular, infiltrative masses exhibiting stronger hemosiderin deposition and more severe disease extents of articular, muscle, and tendon involvement than the localized type.

Immune Cell Infiltration Characteristics of Pigmented Villous Nodular Synovitis and Prediction of Potential Diagnostic Markers Based on Bioinformatics

Background

Pigmented villous nodular synovitis (PVNS) is a tumor-like proliferative disease characterized by impairment of daily activities, decreased quality of life, and a high recurrence rate. However, the specific pathological mechanisms are still ill-defined and controversial. The purpose of this study was to define potential diagnostic markers and evaluate immune cell infiltration in the pathogenesis of PVNS.

Method

The expression profile of GSE3698 was reanalyzed in the Gene Expression Omnibus (GEO) database. First, differentially expressed genes (DEGs) were identified using the R package “limma” and analyzed by Gene Ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Next, the DEGs were imported into the STRING database and Cytoscape to construct a protein–protein interaction (PPI) network. Then, cytoHubba and ROC curve analyses were used to determine potential diagnostic biomarkers of PVNS. Finally, we used CIBERSORT to estimate the proportions of 22 immune cell subtypes in PVNS and analyzed the correlation between diagnostic markers and infiltrating immune cells.

Result

We found 139 DEGs (including 93 upregulated genes and 46 downregulated genes). TYROBP, FCER1G, LAPTM5, and HLA-DPB1 were identified as potential diagnostic biomarkers of PVNS. Immune cell infiltration analysis indicated that neutrophils and M2 macrophages might be associated with the genesis and progression of PVNS. Furthermore, our correlation analysis of diagnostic markers and infiltrating immune cells found that TYROBP, FCER1G, LAPTM5, and HLA-DPB1 were positively correlated with M2 macrophage infiltration and that neutrophils, TYROBP, FCER1G, and LAPTM5 were negatively correlated with plasma cell infiltration.

Conclusions

We identified TYROBP, FCER1G, LAPTM5, and HLA-DPB1 as potential diagnostic markers for PVNS and concluded that immune cell infiltration plays an important role in the genesis and progression of PVNS.

CSF1 receptor inhibition of tenosynovial giant cell tumor using novel disease-specific MRI measures of tumor burden

Aim: Monitoring treatment of tenosynovial giant cell tumor (TGCT) is complicated by the irregular shape and asymmetrical growth of the tumor. We compared responses to pexidartinib by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 with those by tumor volume score (TVS) and modified RECIST (m-RECIST). Materials & methods: MRIs acquired every two cycles were assessed centrally using RECIST 1.1, m-RECIST and TVS and tissue damage score (TDS). Results: Thirty-one evaluable TGCT patients were treated with pexidartinib. From baseline to last visit, 94% of patients (29/31) showed a decrease in tumor size (median change: -60% [RECIST], -66% [m-RECIST], -79% [TVS]). All methods showed 100% disease control rate. For TDS, improvements were seen in bone erosion (32%), bone marrow edema (58%) and knee effusion (46%). Conclusion: TVS and m-RECIST offer potentially superior alternatives to conventional RECIST for monitoring disease progression and treatment response in TGCT. TDS adds important information about joint damage associated with TGCT.

Turalio risk evaluation and mitigation strategy for treatment of tenosynovial giant cell tumor: framework and experience

For drugs with enhanced serious safety risks, Risk Evaluation and Mitigation Strategy (REMS) may be required. Pexidartinib is approved for treatment of adult symptomatic tenosynovial giant cell tumor (TGCT) associated with severe morbidity or functional limitations and not amenable to improvement with surgery. Its approval was conditional on its prescription via a mandatory REMS due to serious and potentially fatal liver injury seen in clinical trials. Turalio^® REMS aims to mitigate this risk by ensuring provider education on pexidartinib use and required REMS components, prescriber adherence to baseline and periodic monitoring, and enrolling patients in a registry to further assess safe use and acute, chronic and irreversible hepatotoxicity. Through Turalio REMS, benefits of treating patients with pexidartinib may be preserved.

Giant Cell Tumor of Bone Versus Tenosynovial Giant Cell Tumor - Similarities and Differences

Giant cell tumor of bone (GCTB) and tenosynovial giant cell tumor (TGCT) share misleadingly similar names, soft texture and brown color macroscopically, osteoclast-like multinucleated giant cells microscopically and localisation in the musculoskeletal system. However, these two tumor types are biologically and clinically two distinct entities with different natural courses of progression and considerably different modes of surgical and medical treatment. In this article, we provide a detailed update on the similarities and the differences between both tumor types.GCTB is a locally aggressive osteolytic bone tumor, commonly seen in patients in their third decade of life. It usually occurs as a solitary lesion in the meta-epiphyseal region of long bones. It can be diagnosed using plain radiographic imaging, CT radiography or MRI to estimate the tumor extent, soft tissue and joint involvement. GCTB is usually treated with intralesional excision by curettage. Systemically, it can be treated with bisphosphonates and denosumab or radiotherapy.TGCT is a rare, slowly progressing tumor of synovial tissue, affecting the joint, tendon sheath or bursa, mostly seen in middle-aged patients. TGCT is usually not visible on radiographs and MRI is mostly used to enable assessment of potential bone involvement and distinguishing between two TGCT types. Localised TGCT is mostly treated with marginal surgical resection, while diffuse TGCT is optimally treated with total synovectomy and is more difficult to remove. Additionally, radiotherapy, intraarticular injection of radioactive isotopes, anti-TNF-α antibodies and targeted medications may be used.

Diffuse-Type Tenosynovial Giant Cell Tumor of the Knee with Concurrent Polymicrobial Infection (Klebsiella oxytoca and Group B Streptococcus)

Tenosynovial giant cell tumors (TGCT) are a rare class of benign proliferative tumors that are classified according to their presentation: localized-type (L-TGCT) or diffuse-type (D-TGCT). TGCT is synonymous with pigmented villonodular synovitis (PVNS). We describe the unique case of a 56-year-old obese male with type 2 diabetes who had polymicrobial septic arthritis of his left knee joint with concurrent D-TGCT in the same knee. While on a vacation, he noticed spontaneous left knee pain and swelling with an acute onset of fever. He was diagnosed with septic arthritis that was attributed to hematogenous spread from a leg laceration. The septic arthritis was treated with arthroscopic lavage and debridement, including simultaneous excision of the D-TGCT lesions, followed by intravenous ceftriaxone. Cultures of the synovial tissue that were obtained during arthroscopy grew Klebsiella oxytoca and beta-hemolytic (group B) Streptococcus agalactiae. We were not able to find another reported case of any joint with (1) a polymicrobial bacterial infection that included Klebsiella oxytoca and (2) concurrent bacterial septic arthritis and TGCT.

Case Report: Extra-Articular Diffuse Tenosynovial Giant Cell Tumor of the Temporomandibular Joint

Diffuse tenosynovial giant cell tumor (D-TSGCT) is a benign but locally destructive tumor of synovium that may involve joints, tendon sheaths, and bursae. Its occurrence in the temporomandibular joint (TMJ) is extremely rare. The authors reported a case of 48-year-old man with an extra-articular D-TSGCT in the TMJ with medial cranial fossa extension. computed tomography (CT) and magnetic resonance imaging (MRI) features are described. The lesion was a cystic-solid mass centered at the temporal bone without involvement of the condylar head, and its solid component presented high-density on CT and hypointensity on MRI. No signs of recurrence or metastasis was observed during 12-months of follow-up. The present report suggested the potential characteristics of radiologic imaging of D-TSGCT in TMJ.

Tenosynovial giant cell tumor in the foot and ankle

BACKGROUND

Tenosynovial giant cell tumor (TSGCT) originates from the synovial cells of the tendon sheath and is the most common soft tissue tumor of the foot and ankle. Due to the lack of clinical data about TSGCT in the foot and ankle, this study was performed with the aim of investigating the clinical characteristics, and surgical outcomes that might predict the likelihood of recurrence.

METHODS

Clinical data, obtained from the pathology records and the clinic files, along with the tumor subtype, local recurrence, and patient functional status among 26 cases of TSGCT were evaluated with the mean 73 months follow-up period.

RESULTS

There were 26 patients including 16 males and 10 females with a mean age of 40 years, who underwent surgery. There were 15 localised TSGCT and 11 diffuse TSGCT. The diffuse TSGCT was more likely to be in the hindfoot dorsum (54,5%, 6/11). The localised TSGCT was mostly located in the forefoot (80%, 12/15). The recurrence rate in the diffuse TSGCT was 27,3% (3/11). In the localised TSGCT, recurrence was seen in 6,6% of patients (1/15). The mean AOFAS score was 79.

CONCLUSION

Diffuse TSGCT is more likely to occur in the hindfoot and localised TSGCT is more common in the forefoot. Excision with clear margins is an effective treatment for TSGCT, with good oncological and clinical outcomes. But the orthopaedic surgeons should consider the equilibrium between surgical margins and the functional status of the patient.

Unusual manifestations of diffuse-type tenosynovial giant cell tumor in two patients: importance of radiologic-pathologic correlation

Diffuse-type tenosynovial giant cell tumor (TSGCT) is a rare, locally aggressive neoplasm. It most commonly occurs in the knee, followed by the hip, and has distinctive imaging features, including mass-like foci of low T2 signal intensity, "blooming" on gradient-echo MRI, and pronounced uptake on FDG PET/CT. Histologically, TSGCT demonstrates a neoplastic population of mononuclear cells admixed with hemosiderin-laden macrophages, foamy histiocytes, inflammatory cells, and osteoclast-like giant cells. In cases where diffuse-type TSGCT presents in an uncommon location or with atypical features, the imaging diagnosis may be challenging. Furthermore, because of its polymorphous appearance, it may be mistaken microscopically for other neoplastic and non-neoplastic histiocytic lesions. Herein, we present two cases of diffuse-type TSGCT presenting as large masses, and underscore the importance of radiologic-pathologic correlation for accurate diagnosis.

Long-term efficacy of imatinib mesylate in patients with advanced Tenosynovial Giant Cell Tumor

Tenosynovial giant cell tumors (TGCT), are rare colony stimulating factor-1(CSF-1)-driven proliferative disorders affecting joints. Diffuse-type TGCT often causes significant morbidity due to local recurrences necessitating multiple surgeries. Imatinib mesylate (IM) blocks the CSF-1 receptor. This study investigated the long term effects of IM in TGCT. We conducted an international multi-institutional retrospective study to assess the activity of IM: data was collected anonymously from individual patients with locally advanced, recurrent or metastatic TGCT. Sixty-two patients from 12 institutions across Europe, Australia and the United States were identified. Four patients with metastatic TGCT progressed rapidly on IM and were excluded for further analyses. Seventeen of 58 evaluable patients achieved complete response (CR) or partial response (PR). One- and five-year progression-free survival rates were 71% and 48%, respectively. Thirty-eight (66%) patients discontinued IM after a median of 7 (range 1–80) months. Reported adverse events in 45 (78%) patients were among other edema (48%) and fatigue (50%), mostly grade 1–2 (89%). Five patients experienced grade 3–4 toxicities. This study confirms, with additional follow-up, the efficacy of IM in TGCT. In responding cases we confirmed prolonged IM activity on TGCT symptoms even after discontinuation, but with high rates of treatment interruption and additional treatments.

Surgical Treatment of Localized-Type Tenosynovial Giant Cell Tumors of Large Joints: A Study Based on a Multicenter-Pooled Database of 31 International Sarcoma Centers

BACKGROUND

Localized-type tenosynovial giant cell tumor (TGCT) is a rare, neoplastic disease with only limited data supporting treatment protocols. We describe treatment protocols and evaluate their oncological outcome, complications, and functional results in a large multicenter cohort of patients. A secondary study aim was to identify factors associated with local recurrence after surgical treatment.

METHODS

Patients with histologically proven localized TGCT of a large joint were included if they had been treated between 1990 and 2017 in 1 of 31 tertiary sarcoma centers. Of 941 patients with localized TGCT, 62% were female. The median age at initial treatment was 39 years, and the median duration of follow-up was 34 months. Sixty-seven percent of the tumors affected the knee, and the primary treatment at the tertiary center was 1-stage open resection in 73% of the patients. Proposed factors for predicting a first local recurrence after treatment in the tertiary center were tested in a univariate analysis, and those that demonstrated significance were subsequently included in a multivariate analysis.

RESULTS

The localized TGCT recurred in 12% of all cases, with local-recurrence-free rates at 3, 5, and 10 years of 88%, 83%, and 79%, respectively. The strongest factor for predicting recurrent disease was a prior recurrence (p < 0.001). Surgical treatment decreased pain and swelling in 71% and 85% of the patients, respectively, and such treatment was associated with complications in 4% of the patients. Univariate and multivariate analyses of the patients who had not undergone therapy previously yielded positive associations between local recurrence and a tumor size of ≥5 cm versus <5 cm (hazard ratio [HR] = 2.50; 95% confidence interval [CI] = 1.32 to 4.74; p = 0.005). Arthroscopy (versus open surgery) was significantly associated with tumor recurrence in the univariate analysis (p = 0.04) but not in the multivariate analysis (p = 0.056).

CONCLUSIONS

Factors associated with recurrence after resection of localized-type TGCT were larger tumor size and initial treatment with arthroscopy. Relatively low complication rates and good functional outcomes warrant an open approach with complete resection when possible to reduce recurrence rates in high-risk patients.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Pigmented Villonodular Synovitis Presenting as Unilateral Hearing Loss: Review of the Literature and Case Report

BACKGROUND/AIMS

To review the existing literature on pigmented villonodular synovitis (PVNS) of the temporomandibular joint (TMJ) and report a rare case of PVNS of the TMJ presenting with unilateral hearing loss.

METHODS

Review of the existing literature and a description of personal experience with PVNS of the TMJ presenting with unilateral hearing loss.

RESULTS

Review of the existing literature revealed 76 reported cases of PVNS of the TMJ. The most common presenting symptom was of a slowly enlarging mass or swelling of the preauricular area, with dysfunctional TMJ also frequently reported. All patients underwent surgical excision with some pursuing radiation as adjuvant therapy. Presented Patient: A 46-year-old man presented with several months of unilateral subjective hearing loss and aural fullness. Imaging revealed a mass centered along the superior TMJ with expansion through the squamous temporal bone and extra-axial intracranial extension into the middle cranial fossa. Imaging characteristics and fine-needle aspiration biopsy were consistent with PVNS.

INTERVENTION

The patient underwent near-total excision of the mass via frontotemporal craniectomy and lateral temporal bone resection.

FOLLOW-UP

At the 16-month follow-up there was no evidence of disease recurrence.

CONCLUSION

PVNS of the TMJ represents a rare entity that can present with a variety of symptoms including unilateral hearing loss.

The effect of surgery in tenosynovial giant cell tumours as measured by patient-reported outcomes on quality of life and joint function

AIMS

The aim of this study was to evaluate health-related quality of life (HRQoL) and joint function in tenosynovial giant cell tumour (TGCT) patients before and after surgical treatment.

PATIENTS AND METHODS

This prospective cohort study run in two Dutch referral centres assessed patient-reported outcome measures (PROMs; 36-Item Short-Form Health Survey (SF-36), visual analogue scale (VAS) for pain, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)) in 359 consecutive patients with localized- and diffuse-type TGCT of large joints. Patients with recurrent disease (n = 121) and a wait-and-see policy (n = 32) were excluded. Collected data were analyzed at specified time intervals preoperatively (baseline) and/or postoperatively up to five years.

RESULTS

A total of 206 TGCT patients, 108 localized- and 98 diffuse-type, were analyzed. Median age at diagnosis of localized- and diffuse-type was 41 years (interquartile range (IQR) 29 to 49) and 37 years (IQR 27 to 47), respectively. SF-36 analyses showed statistically significant and clinically relevant deteriorated preoperative and immediate postoperative scores compared with general Dutch population means, depending on subscale and TGCT subtype. After three to six months of follow-up, these scores improved to general population means and continued to be fairly stable over the following years. VAS scores, for both subtypes, showed no statistically significant or clinically relevant differences pre- or postoperatively. In diffuse-type patients, the improvement in median WOMAC score was statistically significant and clinically relevant preoperatively versus six to 24 months postoperatively, and remained up to five years' follow-up.

CONCLUSION

Patients with TGCT report a better HRQoL and joint function after surgery. Pain scores, which vary hugely between patients and in patients over time, did not improve. A disease-specific PROM would help to decipher the impact of TGCT on patients' daily life and functioning in more detail. Cite this article: Bone Joint J 2019;101-B:272-280.

Chondroid Tenosynovial Giant Cell Tumor of the Temporomandibular Joint: A Rare Case Report

Tenosynovial giant cell tumor of diffuse type (TGCT-d) or pigmented villonodular synovitis (PVNS) is a locally aggressive lesion that mostly affects the joints of long bones. Chondroid tenosynovial giant cell tumor (CTGCT) or PVNS with chondroid metaplasia is a rare distinct subset of synovial tumors that has a predilection for the TMJ. We report a rare case of CTGCT in the TMJ, initially misdiagnosed as temporomandibular disorder (TMD). A 51-year-old woman was referred to the surgeon with the chief complaint of TMJ pain for 5 years and a past history of an unsuccessful TMD treatment. Extraoral examination revealed discrete preauricular swelling and restricted mandibular range of motion. Panoramic radiograph and computerized tomography showed destruction of the mandibular fossa and condyle. Histologically, the tumor was composed by large mononuclear cells with prominent eosinophilic cytoplasm and grooved nuclei, small histiocytoid cells, osteoclast-like multinucleated cells, brown pigmentation and areas of chondroid metaplasia. Morphological and immunohistochemical characteristics lead to the final diagnosis of CTGCT. The rarity of CTGCT could be attributed to the lack of recognition of this lesion, with cases diagnosed as chondroblastomas, synovial chodromatosis and chondrosarcoma. The patient received immediate reconstruction and recurrence was found 22 months after initial intervention. TGCT-d and CTGCT of the TMJ can present similar symptoms to TMD, but clinicians must distinguish both lesions by complete examination, imaging and, when necessary, histopathologic evaluation.

Burden of Illness Associated with Tenosynovial Giant Cell Tumors

PURPOSE

Little is known about the burden of illness in patients with tenosynovial giant cell tumors (TGCT), which are rare, typically benign, lesions of the synovial tissue including giant cell tumor of the tendon sheath (GCT-TS) and pigmented villonodular synovitis (PVNS). The objective of this study was to describe health care resource use and costs for patients with GCT-TS and PVNS, which are rare and typically benign TGCT.

METHODS

A retrospective cohort study design was used to analyze administrative claims for adult commercial and Medicare Advantage health plan enrollees with evidence of GCT-TS and PVNS from January 1, 2006 through March 31, 2015. Participants were continuously enrolled for 12 months before (pre-index period) and 12 months after (post-index period) the date of the first tenosynovial giant cell tumor (TGCT) claim (index date). Preindex and postindex measures were compared using the McNemar test and Wilcoxon signed-rank test. Results were stratified by TGCT type.

FINDINGS

The study identified 4664 patients with TGCT, 284 with GCT-TS, and 4380 with PVNS. Mean age (GCT-TS group: 50 years; PVNS group: 51 years) and sex distributions (GCT-TS group: 60.2% female; PVNS group: 59.5% female) were similar for each group. Most patients with GCT-TS (78.2%) had at least one postindex surgery, compared with 38.7% of patients with PVNS. Mean total health care costs increased from $8943 in the preindex period to $14,880 in the postindex period (P < 0.001) for GCT-TS and from $13,221 in the preindex period to $17,728 in the postindex period (P < 0.001) for PVNS. Preindex to postindex ambulatory costs increased nearly 120% for patients with GCT-TS ($4340 to $9570, P < 0.001) and 50% for patients with PVNS ($6782 to $10,278, P < 0.001), and physical therapy use increased significantly during the same period (GCT-TS: 18% to 40%, P < 0.001; PVNS: 38% to 60%, P < 0.001).

IMPLICATIONS

Costs increased substantially 1 year after the first TGCT claim, with more than half the costs covering ambulatory care. These results suggest a high health care burden once TGCT is identified.

Higher incidence rates than previously known in tenosynovial giant cell tumors

Background and purpose - Tenosynovial giant cell tumors (TGCT) are rare, benign tumors, arising in synovial lining of joints, tendon sheaths, or bursae. 2 types are distinguished: localized, either digits or extremity, and diffuse lesions. Current TGCT incidence is based on 1 single US-county study in 1980, with an incidence of 9 and 2 per million person-years in localized (including digits) and diffuse TGCT, respectively. We aim to determine nationwide and worldwide incidence rates (IR) in TGCT affecting digits, localized-extremity TGCT and diffuse-type TGCT. Material and methods - Over a 5-year period, the Dutch Pathology Registry (PALGA) identified 4,503 pathology reports on TGCT. Reports affecting digits were solely used for IR calculations. Reports affecting extremities were clinically evaluated. Dutch IRs were converted to world population IRs. Results - 2,815 (68%) digits, 933 (23%) localized-extremity and 390 (9%) diffuse-type TGCT were identified. Dutch IR in digits, localized-extremity, and diffuse-type TGCT was 34, 11 and 5 per million person-years, respectively. All 3 groups showed a female predilection and highest number of new cases in age category 40-59 years. The knee joint was most often affected: localized-extremity (46%) and diffuse-type (64%) TGCT, mostly treated with open resection: localized (65%) and diffuse (49%). Reoperation rate due to local recurrence for localized-extremity was 9%, and diffuse TGCT 23%. Interpretation - This first nationwide study and detailed analyses of IRs in TGCT estimated a worldwide IR in digits, localized-extremity and diffuse TGCT of 29, 10, and 4 per million person-years, respectively. Recurrence rate in diffuse type is 2.6 times higher, compared with localized extremity. TGCT is still considered a rare disease; however, it is more common than previously understood.

CSF-1R Inhibitor Development: Current Clinical Status

PURPOSE OF REVIEW

Colony-stimulating factor 1 receptor (CSF-1R) and its ligands, CSF-1 and interleukin 34 (IL-34), regulate the function and survival of tumor-associated macrophages, which are involved in tumorigenesis and in the suppression of antitumor immunity. Moreover, the CSF-1R/CSF-1 axis has been implicated in the pathogenesis of pigmented villonodular synovitis (PVNS), a benign tumor of the synovium. As advanced or metastatic malignant solid tumors and relapsed/refractory PVNS remain unresolved therapeutic problems, new approaches are needed to improve the outcome of patients with these conditions.

RECENT FINDINGS

In solid tumors, targeting CSF-1R via either small molecules or antibodies has shown interesting results in vitro but limited antitumor activity in vivo. Concerning PVNS, clinical trials assessing CSF-1R inhibitors have revealed promising initial outcomes. Blocking CSF-1/CSF-1R signaling represents a promising immunotherapy approach and several new potential combination therapies for future clinical testing.

Tenosynovial Giant Cell Tumor: Incidence, Prevalence, Patient Characteristics, and Recurrence. A Registry-based Cohort Study in Denmark

OBJECTIVE

Tenosynovial giant cell tumor (TGCT) is a rare benign proliferative and inflammatory disease arising from synovia of joints, bursae, or tendon sheaths. We aimed to estimate incidence rate and prevalence of TGCT in Denmark, to describe patient characteristics and treatment modalities among patients with TGCT, and to estimate risk of TGCT recurrence.

METHODS

Using registry data on pathology examinations and inpatient and outpatient hospital diagnoses, we identified adult patients with diagnoses of diffuse TGCT (D-TGCT) or localized TGCT (L-TGCT) between 1997 and 2012, followed through 2012. We described patients' characteristics, treatment modalities, and recurrence.

RESULTS

We identified 2087 patients with L-TGCT and 574 patients with D-TGCT. Their incidence rates per million person-years were 30.3 (95% CI 29.1-31.7) and 8.4 (95% CI 7.7-9.1), respectively. At the end of 2012, prevalence per 100,000 persons was 44.3 (95% CI 42.4-46.3) for L-TGCT and 11.5 (95% CI 10.6-12.6) for D-TGCT. Women made up 61% of the patients with L-TGCT and 51% of the patients with D-TGCT. Median age at diagnosis was 47 years. Ten-year risk of recurrence was 9.8% (95% CI 8.4-11.3%) after L-TGCT and 19.1% (95% CI 15.7-22.7%) after D-TGCT.

CONCLUSION

This study contributes evidence about epidemiology of TGCT based on routinely collected population-based data gathered in a setting of universal equal access to healthcare and complete followup.

Multifocal pigmented villonodular synovitis coexisting in both the knee joint and the patella: a case report and literature review

BACKGROUD

Pigmented villonodular synovitis (PVNS) is an uncommon entity of proliferative lesion of the synovium, presenting with different clinical signs and symptoms. PVNS rarely forms an osteolytic lesion in a bone. Here we report a unique case of PVNS with a nodular lesion in the left patella.

CASE PRESENTATION

A 37-year-old female was referred to our hospital with complaints of ongoing left knee pain and a painful and palpable mass in her left popliteal fossa. MRI demonstrated a nodular lesion in the left patella, diffuse affected synovial tissue in the left knee and an extra-articular mass in the left popliteal fossa. After a primary diagnosis of PVNS had been established, combined arthroscopic synovectomy and open resection were performed. The postoperative pathological diagnoses of the resected mass from the popliteal fossa, the affected synovial tissue and the lesion in the patella were consistent with PVNS. At 1-year follow-up, no evidence of recurrence was noted.

CONCLUSIONS

Based on brief literature review of PNVS, we presented a very rare case of PVNS with a nodular lesion in the left patella, diffuse affected synovial tissue in the left knee and an extra-articular mass in the left popliteal fossa.

Cryosurgery as Additional Treatment in Tenosynovial Giant Cell Tumors

Introduction. Tenosynovial giant cell tumors (TGCT) emerge from the synovium and can behave aggressively. Surgical resection is the standard treatment. However, up to half of the patients with diffuse type show recurrences. Several additional treatments have been applied to reduce recurrences; none of these treatments was proven to be superior to surgical resection solely. This article describes the results of additional cryosurgery to surgical resection. Materials and Methods. We retrospectively evaluated 141 TGCT patients, between 1999 and 2007. Twelve patients had additional cryosurgery. The knee (n = 8), hip (n = 2), ankle (n = 1), and elbow (n = 1) were affected. Primary outcome variables were treatment indications, recurrences, and complications. Results. Indications for additional cryosurgery were extended disease, bone involvement, and locations that are difficult to surgically get disease-free such as cruciate ligaments. Five patients had recurrent disease, all of which had prior treatments. None of the primary treated patients had recurrent disease. One patient had a deep infection. Discussion. Cryosurgery may serve as an additional treatment for diffuse TCGT in selected cases. However, because of the small number of patients and the heterogeneous group we could not prove an advantage of additional cryosurgery over surgical resection only. Cryosurgery should be considered for further evaluation in a prospective study. If there is any effect it would be helpful, especially in patients with multiple TGCT recurrences.

Arthroplasty for tenosynovial giant cell tumors

Background and purpose - Tenosynovial giant cell tumors (t-GCTs) can behave aggressively locally and affect joint function and quality of life. The role of arthroplasty in the treatment of t-GCT is uncertain. We report the results of arthroplasty in t-GCT patients. Patients and methods - t-GCT patients (12 knee, 5 hip) received an arthroplasty between 1985 and 2015. Indication for arthroplasty, recurrences, complications, quality of life, and functional scores were evaluated after a mean follow-up time of 5.5 (0.2-15) years. Results - 2 patients had recurrent disease. 2 other patients had implant loosening. Functional scores showed poor results in almost half of the knee patients. 4 of the hip patients scored excellent and 1 scored fair. Quality of life was reduced in 1 or more subscales for 2 hip patients and for 5 knee patients. Interpretation - In t-GCT patients with extensive disease or osteoarthritis, joint arthroplasty is an additional treatment option. However, recurrences, implant loosening, and other complications do occur, even after several years.

Structure-Guided Blockade of CSF1R Kinase in Tenosynovial Giant-Cell Tumor

BACKGROUND

Expression of the colony-stimulating factor 1 (CSF1) gene is elevated in most tenosynovial giant-cell tumors. This observation has led to the discovery and clinical development of therapy targeting the CSF1 receptor (CSF1R).

METHODS

Using x-ray co-crystallography to guide our drug-discovery research, we generated a potent, selective CSF1R inhibitor, PLX3397, that traps the kinase in the autoinhibited conformation. We then conducted a multicenter, phase 1 trial in two parts to analyze this compound. In the first part, we evaluated escalations in the dose of PLX3397 that was administered orally in patients with solid tumors (dose-escalation study). In the second part, we evaluated PLX3397 at the chosen phase 2 dose in an extension cohort of patients with tenosynovial giant-cell tumors (extension study). Pharmacokinetic and tumor responses in the enrolled patients were assessed, and CSF1 in situ hybridization was performed to confirm the mechanism of action of PLX3397 and that the pattern of CSF1 expression was consistent with the pathological features of tenosynovial giant-cell tumor.

RESULTS

A total of 41 patients were enrolled in the dose-escalation study, and an additional 23 patients were enrolled in the extension study. The chosen phase 2 dose of PLX3397 was 1000 mg per day. In the extension study, 12 patients with tenosynovial giant-cell tumors had a partial response and 7 patients had stable disease. Responses usually occurred within the first 4 months of treatment, and the median duration of response exceeded 8 months. The most common adverse events included fatigue, change in hair color, nausea, dysgeusia, and periorbital edema; adverse events rarely led to discontinuation of treatment.

CONCLUSIONS

Treatment of tenosynovial giant-cell tumors with PLX3397 resulted in a prolonged regression in tumor volume in most patients. (Funded by Plexxikon; ClinicalTrials.gov number, NCT01004861.).

CSF1R inhibition with emactuzumab in locally advanced diffuse-type tenosynovial giant cell tumours of the soft tissue: a dose-escalation and dose-expansion phase 1 study

BACKGROUND

Diffuse-type tenosynovial giant cell tumour (dt-GCT) of the soft tissue (alternatively known as pigmented villonodular synovitis), an orphan disease with unmet medical need, is characterised by an overexpression of colony-stimulating factor 1 (CSF1), and is usually caused by a chromosomal translocation involving CSF1. CSF1 receptor (CSF1R) activation leads to the recruitment of CSF1R-expressing cells of the mononuclear phagocyte lineage that constitute the tumor mass in dt-GCT. Emactuzumab (RG7155) is a novel monoclonal antibody that inhibits CSF1R activation. We have assessed the safety, tolerability and activity of emactuzumab in patients with Dt-GCT of the soft tissue.

METHODS

In this phase 1, first-in-human dose-escalation and dose-expansion study, eligible patients were aged 18 years or older with dt-GCT of the soft tissue with locally advanced disease or resectable tumours requiring extensive surgery, an Eastern Cooperative Oncology Group performance status of 1 or less, measurable disease according to Response Evaluation Criteria In Solid Tumors version 1.1, and adequate end-organ function. Patients with GCT of the bone were not eligible. Patients received intravenous emactuzumab at 900 mg, 1350 mg, or 2000 mg every 2 weeks in the dose-escalation phase and at the optimal biological dose in a dose-expansion phase. The primary objective was to evaluate the safety and tolerability of emactuzumab, and to determine the maximum tolerated dose or optimal biological dose. All treated patients were included in the analyses. Expansion cohorts are currently ongoing. This study is registered with ClinicalTrials.gov, number NCT01494688.

FINDINGS

Between July 26, 2012, and Oct 21, 2013, 12 patients were enrolled in the dose-escalation phase. No dose-limiting toxicities were noted in the dose-escalation cohort; on the basis of pharmacokinetic, pharmacodynamic, and safety information, we chose a dose of 1000 mg every 2 week for the dose-expansion cohort, into which 17 patients were enrolled. Owing to different cutoff dates for safety and efficacy readouts, the safety population comprised 25 patients. Common adverse events after emactuzumab treatment were facial oedema (16 [64%] of 25 patients), asthenia (14 [56%]), and pruritus (14 [56%]). Five serious adverse events (periorbital oedema, lupus erythematosus [occurring twice], erythema, and dermohypodermitis all experienced by one [4%] patient each) were reported in five patients. Three of the five serious adverse events-periorbital oedema (one [4%]), lupus erythematosus (one [4%]), and dermohypodermitis (one [4%])-were assessed as grade 3. Two other grade 3 events were reported: mucositis (one [4%]) and fatigue (one [4%]). 24 (86%) of 28 patients achieved an objective response; two (7%) patients achieved a complete response.

INTERPRETATION

Further study of dt-GCT is warranted and different possibilities, such as an international collaboration with cooperative groups to assure appropriate recruitment in this rare disease, are currently being assessed.

FUNDING

F Hoffmann-La Roche.

Long-term follow-up results of primary and recurrent pigmented villonodular synovitis

OBJECTIVE

Adequate documentation of the outcome of treatment of pigmented villonodular synovitis (PVNS) is sparse. Available case series show relatively short follow-up times and often combine locations or subtypes to increase patient numbers. This article describes the long-term follow-up of a single institution's large consecutive series of PVNS.

METHODS

Retrospectively, 107 PVNS patients were identified between 1985 and 2011 by searching pathology and radiology records. Treatment complications, recurrences and quality of life were evaluated. Most patients (85.2%) were primarily or secondarily treated at our institution.

RESULTS

Both subtypes, localized PVNS [29 (27%)] and diffuse PVNS [75 (70%)] were represented. The knee was affected in 88% of patients. Treatments received were surgery, external beam radiotherapy, radiosynovectomy, targeted therapy, immunotherapy or combinations of these. Forty-nine (46%) patients had prior treatment elsewhere. The mean follow-up from diagnosis until last contact was 7.0 years (range 0.3-27.4) for localized PVNS and 14.5 years (range 1.1-48.7) for diffuse PVNS. The 1- and 5-year recurrence-free survival rates for diffuse PVNS were 69% and 32%, respectively. Quality of life, estimated by 36-item Short Form Health Survey (SF-36) scores, were not significantly different between localized and diffuse PVNS. However, both patient groups scored lower than the general population norms on the general health component (59.2 and 56.3, respectively, P < 0.05).

CONCLUSION

Recurrence rates of PVNS increase with time. Long-term follow-up shows, particularly in diffuse PVNS, it is a continually recurring problem, and over time it becomes increasingly difficult to cure. The quality of life is decreased in patients with PVNS compared with the general population.