Chondroid Synoviocytic Neoplasm: A Clinicopathologic, Immunohistochemical, and Molecular Genetic Study of a Distinctive Tumor of Synoviocytes.

Tumors resembling tenosynovial giant cell tumor (TGCT) but additionally forming chondroid matrix are rare and most often involve the temporomandibular joint (TMJ). We studied 21 tumors consisting of synoviocytes (large, eosinophilic mononuclear cells containing hemosiderin) and chondroid matrix to better understand these unusual neoplasms. The tumors occurred in 10 males and 11 females, in the age group of 31 to 80 years (median, 50 years) and involved the TMJ region (16), extremities (4), and spine (1). As in conventional TGCT, all were composed of synoviocytes, small histiocytes, foamy macrophages, siderophages, and osteoclast-like giant cells in variably hyalinized background. Expansile nodules of large, moderately atypical synoviocytes were present, in addition to "chondroblastoma-like," "chondroma-like," or "phosphaturic mesenchymal tumor-like" calcified matrix. The synoviocytes expressed clusterin (17/19) and less often desmin (3/15). The tumors were frequently CSF1 positive by chromogenic in situ hybridization (8/13) but at best weakly positive for CSF1 by immunohistochemistry (0/3). Background small histiocytes were CD163 positive (12/12). All were FGF23 negative (0/10). Cells within lacunae showed a synoviocytic phenotype (clusterin positive; S100 protein and ERG negative). RNA-Seq was successful in 13 cases; fusions were present in 7 tumors, including FN1::TEK (5 cases); FN1::PRG4 (2 cases); and MALAT1::FN1, PDGFRA::USP35, and TIMP3::ZCCHC7 (1 case each). Three tumors contained more than 1 fusion (FN1::PRG4 with TIMP3::ZCCHC7, FN1::TEK with FN1::PRG4, and FN1::TEK with MALAT1::FN1). Clinical follow-up (17 patients; median follow-up duration 38 months; range 4-173 months) showed 13 (76%) to be alive without evidence of disease and 4 (24%) to be alive with persistent/recurrent local disease. No metastases or deaths from disease were observed. We conclude that these unusual tumors represent a distinct category of synoviocytic neoplasia, which we term "chondroid synoviocytic neoplasm," rather than simply ordinary TGCT with cartilage. Despite potentially worrisome morphologic features, they appear to behave in at most a locally aggressive fashion.

MANEUVER: A Phase III study of pimicotinib to assess efficacy and safety in tenosynovial giant cell tumor patients.

Tenosynovial giant cell tumor (TGCT) is a rare, locally invasive soft tissue tumor arising from the synovium of joints, bursa and tendon sheaths and is associated with the overexpression of the colony-stimulating factor 1 (CSF-1) gene. Pimicotinib is an orally available, highly selective and potent small molecule CSF-1 receptor (CSF-1R) inhibitor with robust efficacy and safety profile in patients with TGCT and is under development in multiple diseases. In an open-label Phase I study in patients with TGCT not amenable to surgery, pimicotinib showed superior efficacy and safety. In this article, we elucidate the rationale and study design of the multi-region Phase III MANEUVER trial (NCT05804045), which is designed to assess the efficacy and safety of pimicotinib in patients with TGCT not amenable to surgical resection in Asia, North America and Europe.

Tenosynovial giant cell tumor (TGCT) is a rare soft tissue tumor which grows in the soft tissues around joints or parts of the body used for movement. It is caused by high levels of a type of protein called CSF-1. Even though surgery is a preferred treatment option, some patients may be unable to have surgery because of where the tumor is, how complicated it is, or the risk of serious problems or illness after the surgery. Therefore, new treatments that are safe, effective and that help people live well are still needed for this disease. Pimicotinib is a medicine which blocks CSF-1, and researches have shown that it is safe and effective for treating TGCT in smaller, early study. To confirm these results, researchers have started a larger study, known as MANEUVER, in some parts of Asia, North America and Europe. This study will confirm if pimicotinib is safe and effective in patients with TGCT who may not be able to have surgery.Clinical Trial Registration: NCT05804045 (ClinicalTrials.gov).

The MOTION study: a randomized, phase III study of vimseltinib for the treatment of tenosynovial giant cell tumor.

Tenosynovial giant cell tumor (TGCT) is a rare, locally aggressive neoplasm that occurs in the synovium of joints, bursae, or tendon sheaths and is caused by upregulation of the CSF1 gene. Vimseltinib is an oral switch-control tyrosine kinase inhibitor specifically designed to selectively and potently inhibit the CSF1 receptor. Here, we describe the rationale and design for the phase III MOTION trial (NCT05059262), which aims to evaluate the efficacy and safety of vimseltinib in participants with TGCT not amenable to surgical resection. In part 1, participants are randomized to receive vimseltinib 30 mg twice weekly or matching placebo for ≤24 weeks. Part 2 is a long-term treatment phase in which participants will receive open-label vimseltinib.

Tenosynovial giant cell tumor (or TGCT) is a rare, noncancerous tumor that grows in the soft tissue lining the spaces of joints and bursae (fluid-filled sacs that work to reduce friction in the joints). These tumors are linked to increased levels of a protein called CSF1. While this condition is typically treated with surgery, some patients may not be candidates for surgical removal of the tumor due to factors such as location or complexity of the tumor; therefore, drug treatments are needed to help these patients. Vimseltinib is an investigational oral drug specifically designed to inhibit the receptor to which the CSF1 protein binds. In this article, we describe the rationale and design for a phase III clinical trial that will test how well vimseltinib works in participants with TGCT who are not candidates for surgery. In the first part of the study, participants are randomly assigned to receive vimseltinib 30 mg twice weekly or a matching placebo (inactive substance) for up to 24 weeks. This first part is blinded, so participants will not know if they are receiving vimseltinib or the placebo. The second part of the study is a long-term treatment phase in which all participants will receive vimseltinib (unblinded). Clinical Trial Registration: NCT05059262 (ClinicalTrials.gov).

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.

Treatment patterns in patients with tenosynovial giant cell tumors in the USAThis database study is the first investigation of how drugs are used to treat patients with tenosynovial giant cell tumor (TGCT) in the real world. We researched adult TGCT patients from IQVIA's prescription and medical claims databases who started treatment with pexidartinib (N = 82) or other non-US FDA-approved systemic therapies (N = 263). The patients included in this analysis were mostly women (61.0 and 50.6%) and their median age was 47 and 54 years for pexidartinib and other non-FDA-approved systemic therapies, respectively. The patients treated with pexidartinib were most likely to remain on treatment (54.0%) at the end of the first year. Most patients (79.3%) started pexidartinib treatment at a total daily dose of 800 mg/day, as per the product label. Only 34.1% of patients had reduced medication dose during follow-up. Of note, this study found that TGCT patients were treated with other systemic therapies which remain unproven to be safe and effective in medical studies of TGCT. Given the unmet need, and with pexidartinib being the only approved systemic treatment in USA, there is an opportunity for the larger population of adult TGCT patients to benefit from its use. Further research is needed to identify barriers for access to pexidartinib and treatment of TGCT patients.

Contribution of the Ultrasound Techniques in the Evaluation of Knee Joint Damage in the Case of Pigmented Villonodular Synovitis and Rheumatoid Arthritis.

OBJECTIVES: This is a prospective study to evaluate the clinical value of high-frequency ultrasound (HFUS), superb microvascular imaging (SMI), and contrast-enhanced ultrasound (CEUS) in differentiation of pigmented villonodular synovitis (PVNS) and highly active rheumatoid arthritis (RA). METHODS: Twenty PVNS patients and 24 active RA patients were selected to undergo HFUS, SMI, and CEUS examinations. The characteristics of HFUS, SMI, and CEUS in PVNS and RA were compared, and the differential diagnosis performances of HFUS, SMI, and CEUS in PVNS and RA were evaluated by receiver operating characteristic (ROC) analysis. RESULTS: There were statistically significant in joint effusion, synovial thickness, synovial morphology, synovial echo, synovial vessel shape, synovial enhanced direction, and enhanced pattern between PVNS and RA (P < .05). However, no statistically significant were found in bone erosion, synovial boundary, blood signal grading of synovium, synovial enhanced strength, and CEUS quantitative parameters (including PI, TTP, S, MTT, and AUC) (P > .05). The AUC of HFUS, SMI, and CEUS for differential diagnosis PVNS and RA were 0.832, 0.675, and 0.817, respectively. The AUC of HFUS + SMI, HFUS + CEUS, SMI + CEUS, HFUS + SMI + CEUS were 0.923, 0.940, 0.817, and 0.940, respectively. The AUC of HFUS + SMI and HFUS + CEUS was higher than that of each alone (P < .05). CONCLUSIONS: HFUS, SMI, and CEUS can be used as supplementary methods for diagnosis and differential diagnosis in PVNS and active RA. What is more, the combination of HFUS + SMI and HFUS + CEUS was suggested.

Intra-labral pigmented villonodular synovitis: a rare case in two adult patients.

This article discusses two rare cases of intra-labral pigmented villonodular synovitis (PVNS) of the hip. The hip joint represents the second most common location of pigmented villonodular synovitis, second to the knee [1]. The majority of hip PVNS cases either diffusely involve the synovium or are focal lesions within the joint. The lesions and synovium show foci of low signal intensity related to hemosiderin deposition, a finding that differentiates PVNS from other causes of synovial proliferation. Our case report presents two rare manifestations of PVNS lesions localized within the hip labrum. This presentation could easily be mistaken for a cyst by imaging modality. Despite the rarity of this condition, we highlight the importance of questioning the possibility of intra-labral PVNS, when patients have persistent hip pain not responding to therapy and atypical imaging findings. Highlighting this rare presentation is crucial for establishing the correct diagnosis, guiding treatment, and obtaining the best clinical outcome.

Diffuse pigmented villonodular synovitis treated with arthroscopic total synovial peel.

BACKGROUND: Diffuse pigmented villonodular synovitis (PVNS) is prone to recurrence after surgery, and it is difficult to achieve a long-term complete cure. OBJECTIVE: To reduce the recurrence rate of PVNS, the author pioneered the arthroscopic total synovial peel (ATSP). METHODS: From March 2014 to July 2020, a total of 19 patients (6 males and 13 females) with diffuse PVNS of the knee were treated in our department and underwent ATSP. It's 'peel' rather than simple excision. This method is similar to peeling bark. Relapse rates and functional scores were determined, with follow-ups ranging from 12 to 72 months, on average 36 months. RESULTS: Treatment efficacy was assessed by imaging and functional scores. Imaging results indicated a recurrence rate of 10.5%. In patients without recurrence, the visual analog score (VAS) decreased from 4.76 ± 2.02 preoperatively to 1.56 ± 1.15 postoperatively. The Tegner-Lysholm knee function score (TLS) score increased from 67.76 ± 15.64 preoperatively to 90.32 ± 8.32 postoperatively. Compared with the literature, ATSP significantly reduces the postoperative recurrence rate of diffuse PVNS. The preliminarily findings suggest that this approach could greatly reduce the recurrence rate of postoperative PVNS in follow-up studies. CONCLUSION: This approach may be a viable option for treating diffuse PVNS via arthroscopy and is worthy of clinical consideration.

[Localized tenosynovial giant cell tumor : Results from the Histopathological Arthritis Register of the German Society for Orthopedic Rheumatology]. / Der lokalisierte tenosynoviale Riesenzelltumor (L-TSRZT) : Ergebnisse aus dem histopathologischen Arthritisregister der Deutschen Gesellschaft für Orthopädische Rheumatologie.

BACKGROUND: The tenosynovial giant cell tumor (pigmented villonodular synovitis) is a proliferative, mainly benign soft tissue tumor of the tendon sheaths, bursae and joints arising from the synovia. It can be divided into circumscribed localized and destructive diffuse types. Approximately 1% of all joint diseases are due to this entity. The tumor is considered as a rarity. Mostly case studies exist. For this study the focus was set on the localized type (L-TSRZT), which accounts for 90% of the diagnoses of this tumor. Given its rarity, data are limited. Therefore, the research aim was to provide data on prevalence, primary location and sensitivity of clinical versus histopathological diagnosis in a German sample. METHODS: Based on the Histopathological Arthritis Register of the German Society for Orthopedic Rheumatology, the data of the L­TSRZT were retrospectively analyzed (time frame 1 January 2018-28 December 2020). RESULTS: This database contained N = 7595 cases of arthropathy. A total of n = 45 patients with the diagnosis L­TSRZT were identified. The prevalence of the tumor was 0.6%, 95% CI [0.4%, 0.8%], or 5.9 cases per 1000. The primary location involved the finger (48.9%). In 14 of 45 cases the diagnosis was correctly determined from the clinical side, corresponding to a sensitivity of 31.1%, 95% CI [18.2%, 46.7%]. CONCLUSION: For the first time, this paper was able to provide data on a large sample for Germany. Notably, the low sensitivity of the clinical diagnosis confirms the importance of histopathology for diagnosing L­TSRZT.

Surgical management of 144 diffuse-type TGCT patients in a single institution: A 20-year cohort study.

BACKGROUND AND OBJECTIVES: Surgery is the mainstay of treatment for tenosynovial giant cell tumors (TGCTs). However, achieving a cure through surgery alone remains challenging, especially for the diffuse-type (D-TGCT). METHODS: Our goal was to describe the surgical management of patients with D-TGCT related to large joints, treated between 2000 and 2020. We analyzed the effect of (in)complete resections and the presence of postoperative tumor (POT) on magnetic resonance imaging (MRI) on radiological and clinical outcomes. RESULTS: A total of 144 patients underwent open surgery for D-TGCT, of which 58 (40%) had treatment before. The median follow-up was 65 months. One hundred twenty-five patients underwent isolated open surgeries, in which 25 (20%) patients' D-TGCT was intentionally removed incompletely. POT presence on the first postoperative MRI was observed in 64%. Both incomplete resections and POT presence were associated with higher rates of radiological progression (73% vs. 44%; Kaplan-Meier [KM] analysis p = 0.021) and 59% versus 7%; KM analysis p < 0.001), respectively. Furthermore, patients with POT presence clinically worsened more often than patients without having POT (49% vs. 24%; KM analysis p = 0.003). CONCLUSIONS: D-TGCT is often resected incompletely and tumor presence is commonly observed on the first postoperative MRI, resulting in worse radiological and clinical outcomes. Therefore, surgeons should try to remove D-TGCT in toto and consider other multimodal therapeutic strategies.

Clinical outcomes of patients with pigmented villonodular synovitis of the shoulder after arthroscopic synovectomy.

BACKGROUND: Shoulder pigmented villonodular synovitis (PVNS) is a severe clinical condition, while few studies have focused on this situation due to its rarity. This study was to investigate the efficacy of arthroscopic treatment of patients diagnosed with shoulder PVNS. METHODS: From Jan 1st, 2010 to Dec. 31st, 2019, 6 patients (5 females and 1 male) diagnosed with shoulder PVNS underwent arthroscopic synovectomy in our hospital and combined rotator cuff repair was performed in 3 of them. The outcomes of this study include Constant score, Visual Analogue Scale (VAS), University of California, Los Angeles (UCLA) score and American Shoulder and Elbow Surgeons (ASES) score. The data were retrieved from the patients' medical records. RESULTS: With a mean follow-up of 52.0 months (range, 28-92 months), the mean difference of Constant, VAS, UCLA and ASES scores were 27.83 ± 21.60, 2.83 ± 2.56, 11.67 ± 10.93 and 17.83 ± 25.35, respectively. Statistically significant improvements were detected in all the patient-reported outcomes except ASES score. One of the patients suffered from recurrence. Two patients suffered from mild complications after the surgeries while both of them achieved satisfactory recovery finally. CONCLUSION: Arthroscopic synovectomy in the setting of shoulder PVNS can improve patients' function. A concurrent rotator cuff repair is recommended if it is needed. The conclusion still needs testifying by further high-quality research with larger sample size.

Clinical outcomes of endoscopic synovectomy with adjuvant radiotherapy of pigmented villonodular synovitis of the hip: a case series of single center.

BACKGROUND: Though radiotherapy has been widely used for knee pigmented villonodular synovitis (PVNS), there is few literatures about radiotherapy for the treatment of PVNS hip. Thus, the purpose of this study was to analyze the clinical outcomes of endoscopic synovectomy with/without radiotherapy postoperatively of PVNS hip. METHODS: We performed a retrospective study of patients who underwent endoscopy in our hospital from November 2010 to January 2021. Inclusion criteria was patients with magnetic resonance image (MRI) signs, endoscopic findings and/or histological evidence of PVNS. Exclusion criteria was patients lost follow-up. All patients underwent synovectomy endoscopically and were divided into two groups depending on receiving postoperative radiotherapy or not. The primary outcome measurements were the recurrence of PVNS, receiving revision, and/or converting to total hip arthroplasty (THA). The secondary outcome measurements were the patient-reported outcome (PRO) collected at pre- and post-operation, which consist of Hip Outcome Score Activities of Daily Living (HOS-ADL), modified Harris Hip Score (mHHS), International Hip Outcome Tool-12 (IHOT-12), Non-arthritic Hip Scale (NAHS), and visual analog scale (VAS). RESULTS: In a case series of 16 patients (8 cases of male, 50%), 4 (25%) cases were localized type and 12 (75%) cases were diffuse type. The average follow-up was 44.8 ± 38.2 months (range,3 to 110). 8 (50%) cases (6 diffuse cases and 2 localized cases) received radiotherapy postoperatively, and the rest (6 diffuse cases and 2 localized cases) received endoscopic treatment alone. At the latest follow-up, 3 (18.75%) cases (2 diffuse cases and 1 localized case) who did not receive radiotherapy converted to arthroplasty. The preoperative HOS-ADL, mHHS, IHOT-12, NAHS, VAS scores of remaining 13 patients were 63.1 ± 19.1 (range,32.0 to 98.8), 54.8 ± 20.1 (range, 10.0 to 77.0), 50.9 ± 15.4 (range, 31.0 to 76.6),51.6 ± 15.9 (range, 20.0 to 84.4), 6.0 ± 1.4 (range,4.0 to 8.0) points, respectively. The latest HOS-ADL, mHHS, IHOT-12, NAHS, VAS scores of the 13 patients were 79.7 ± 10.8 (range, 58.0 to 97.6), 78.6 ± 9.1 (range,55.0 to 87.0), 74.7 ± 9.7 (range, 55.6 to 91.0), 78.9 ± 18.7 (range,20.0 to 92.5), 3.1 ± 1.2 (range,2.0 to 6.0) points respectively. CONCLUSION: Endoscopic synovectomy can achieve satisfactory PRO in PVNS hip patients. Besides, postoperative adjuvant radiotherapy can achieve higher hip survivability than synovectomy alone in this present study.

Tenosynovial giant cell tumor-diffuse type, treated with a novel colony-stimulating factor inhibitor, pexidartinib: initial experience with MRI findings in three patients.

Tenosynovial giant cell tumor-diffuse type (diffuse TSGCT) is a benign but locally aggressive proliferative disorder of the synovium. Treatment is usually surgical, although in cases of extensive disease complete synovectomy is not possible and local recurrence rates are high. Pexidartinib (trade name Turalio®), a colony-stimulating factor-1 (CSF-1) inhibitor, was shown in a recent phase III trial to effectively treat diffuse TSGCT and is FDA approved for the treatment of adult patients with symptomatic diffuse TSGCT associated with severe morbidity or functional limitations and not amenable to improvement with surgery. Pexidartinib is available only through a restricted program under a risk evaluation and mitigation strategy (REMS) because of the risk of hepatotoxicity. Magnetic resonance imaging (MRI) is the preferred imaging modality for the diagnosis and surveillance of TSGCT. Here we present three patients with diffuse TSGCT of the knee who underwent multiple MRIs over several years while on pexidartinib. We describe the disease burden and signal characteristics on MRI and correlate with the response reported in the patients' medical records. Given that the use of pexidartinib and other CSF inhibitors is likely to increase, musculoskeletal radiologists should be aware of this novel non-operative treatment and the MRI appearance of diffuse TSGCT during therapy.

Outcomes of arthroscopic management for pigmented villonodular synovitis of the hip.

INTRODUCTION: Early synovectomy is considered as the main treatment of pigmented villonodular synovitis (PVNS) of the hip in young patients with preserved cartilage. The purpose of the study is to evaluate outcomes of arthroscopic management for PVNS of the hip. METHODS: Patients who underwent primary hip arthroscopy for the treatment of histology-confirmed PVNS by the senior author between January 2012 and December 2016 were retrospectively reviewed. We excluded patients who had less than 1-year follow-up or had undergone primary surgeries with other surgeons and then received revision hip arthroscopic procedures by the senior author. The recurrence of PVNS and postoperative condition of affected hip were assessed by follow-up magnetic resonance imaging (MRI). Patient-reported outcomes of modified Harris hip score (mHHS) and 12-item International Hip Outcome Tool (iHOT-12) were collected at latest follow-up. RESULTS: Nine patients (2 males, 7 females) with a mean age of 24.3 ± 11.2 years (range 14-44 years) were included in this study. Localized PVNS was observed in four patients, and diffuse PVNS was observed in five patients. No patient presented with advanced osteochondral destruction. Five patients received single adjuvant radiosynoviorthesis. No patient had evidence of recurrence based on follow-up MRI. Patient-reported outcomes were obtained in eight patients at mean 55.8 ± 26.1 months (range 24-84 months) after the index surgery. The mean mHHS was 94.6 ± 4.9 (range 84.7-100) and the mean iHOT-12 was 93.3 ± 20.2 (range 50-120). No patient needed secondary surgery during the follow-up period. CONCLUSION: Arthroscopic subtotal synovectomy can offer favorable short to mid-term outcomes in the treatment of hip PVNS in case of no advanced osteochondral damage at presentation.

Tenosynovial giant cell tumor.

Tenosynovial Giant Cell Tumor (TGCT) is a group of typically benign lesions arising from the synovium of joints, bursae and tendon sheaths. Depending on their growth pattern and clinical course, they are divided into localized and diffuse types. It is predominantly caused by a mutation in the stromal cells of the synovial membrane leading to overexpression of the colony stimulating factor 1 that recruits CSF1R-expressing cells of the mononuclear phagocyte lineage into the tumor mass. The lesions contain mainly histiocyte-like and synovial cells accompanied by varying numbers of multinucleated giant cells, mononuclear cells, foam cells, inflammatory cells and hemosiderin deposits. The gold standard for detect- ing and monitoring the disease is MRI, where the characteristic hemosiderin accumulation can be best appreciated, but it is a histological examination that is most conclusive. The main treatment is surgical resection of all pathological tissue, but radio- and chemotherapy are also viable options for certain groups of patients.

Ultrasound-Assisted Posterior Knee Arthroscopy: A Description of the Technique.

Entering the posterior knee with arthroscopy can be difficult. Scar tissue, a tumor, and the obese patient can make instrument placement difficult and risk iatrogenic injury. Ultrasound can be used to visualize the posterior knee and provide direct guidance of instrumentation. We describe the technique and indications for using ultrasound during arthroscopy. Accurate and atraumatic insertion of instruments can be performed with no damage to total knee components or the knee joint. Ultrasound guidance should be considered during difficult posterior knee arthroscopy.

Open synovectomy treatment for intra- and extraarticular localized pigmented villonodular synovitis of the knee: a case report.

BACKGROUND: Pigmented villonodular synovitis (PVNS) is a rare, benign, proliferative neoplastic process that commonly affects synovial-lined anatomic spaces. The diffuse type (DPVNS) is characterized by invasion of the entire joint synovium, while the localized type (LPVNS) is characterized by a relatively normal synovial appearance. This report describes a unique case of massive intraarticular LPVNS with an extraarticular extension through the lateral patellar retinaculum. No similar cases have been found in the literature. CASE PRESENTATION: A 58-year-old woman had a history of hyperuricemia and knee trauma and presented with unilateral knee acute swelling and pain symptoms with sudden onset. Recent expansion of the LPVNS caused the development of a tender palpable soft tissue mass in the anterolateral aspect of the knee and acute reduced mobility. Preoperative magnetic resonance imaging of the knee revealed the presence of only the soft tissue mass and mild degenerative changes. Open synovectomy was performed successfully to excise the mass. Intraoperatively, macroscopic features of the bright brown inflamed synovium suggested LPVNS, which was confirmed histopathologically. Postoperatively, the symptoms of limited mobility and pain were appreciably relieved. Recurrence was not observed during the clinical follow-up at 1, 6 or 18 months after surgery. CONCLUSIONS: Here, we report the unique case of localized pigmented villonodular synovitis of the knee in a misdiagnosed patient with intra- and extraarticular lesion, which might be attributed to the history of knee trauma and the focal defect of the lateral patellar retinaculum. Open synovectomy effectively relieved the symptoms of limited mobility and pain and no recurrence was observed prior to 18 months postoperatively. To reduce misdiagnosis, MRI examinations are recommended for all patients suspected of having PVNS, including those who have a history of hyperuricemia.

Pediatric solid intra-articular masses of the knee: prevalence, imaging features and etiologies.

BACKGROUND: The etiologies of pediatric solid intra-articular soft-tissue masses are not well described and can present diagnostic dilemmas. OBJECTIVE: Our hypothesis was that these entities have a limited differential diagnosis and are mostly benign. MATERIALS AND METHODS: We reviewed knee magnetic resonance imaging (MRI) scans performed at our tertiary care institution between 2001 and 2019 (n=3,915). Our inclusion criterion was knee MRI with a solid intra-articular soft-tissue mass. Our exclusion criteria were cases with no masses or non-solid intra-articular lesions with clear radiologic diagnoses. Multiple radiologic characteristics were evaluated. Radiologic and histological diagnoses were collected when available. Cases without histology were assigned a suspected diagnosis. RESULTS: Twenty-five out of 3,915 (<1%) cases met the inclusion/exclusion criteria. Twenty patients underwent biopsy. Patient age ranged from 1 to 19 years with a mean age of 12 years. Lesion size ranged from 1 to 7 cm with a mean of 3.3 cm. The top three histological diagnoses were pigmented villonodular synovitis (PVNS) (7/20, 35%), vascular malformations (2/20, 10%) and inflammatory arthritis (2/20, 10%). There was one malignant case of synovial sarcoma (1/20, 5%). Of the five cases without biopsies, PVNS was the most common diagnosis (3/5, 60%). Five out of 10 (50%) PVNS cases were focal and 5/10 (50%) were multifocal. All PVNS cases (10/10, 100%) had hypointense signal on T2. CONCLUSION: Solid intra-articular soft-tissue masses of the knee in children are rare, with a prevalence of <1% in our study. The vast majority are benign with PVNS being the most common diagnosis.

Magnetic resonance imaging features of intra-articular tenosynovial giant cell tumor in children.

BACKGROUND: Magnetic resonance imaging (MRI) plays a critical role in disease characterization of intra-articular tenosynovial giant cell tumor. OBJECTIVE: To characterize the MRI features of intra-articular tenosynovial giant cell tumor in children with respect to disease subtype and anatomical location. MATERIALS AND METHODS: This retrospective study included children with tenosynovial giant cell tumor who underwent preoperative MRI between January 2006 and May 2020. Two radiologists reviewed each examination to determine disease subtype, signal intensities and the presence of an effusion, osseous changes, chondromalacia, juxtacapsular disease and concomitant joint involvement. Fisher exact, Mann-Whitney U, and Kruskal-Wallis H tests were used to compare findings between subtypes and locations. RESULTS: Twenty-four children (16 girls, 8 boys; mean age: 13.1±3.8 years) with 19 knee and 5 ankle-hindfoot tenosynovial giant cell tumor had either diffuse (n=15) or localized (n=9) disease. An effusion (P=0.004) was significantly more common with diffuse than localized disease. There was no significant difference in MRI signal (P-range: 0.09-1) or other imaging findings (P-range: 0.12-0.67) between subtypes. Children with knee involvement were significantly more likely to present with diffuse disease while those with ankle-hindfoot involvement all presented with focal disease (P=0.004). Juxtacapsular (n=4) and concomitant proximal tibiofibular joint involvement (n=5) were observed with diffuse disease in the knee. Erosions (P=0.01) were significantly more common in the ankle than in the knee. CONCLUSION: In our study, diffuse tenosynovial giant cell tumor was more common than localized disease, particularly in the knee where juxtacapsular and concomitant proximal tibiofibular joint disease can occur.

Limited usefulness of classic MR findings in the diagnosis of tenosynovial giant cell tumor.

OBJECTIVE: To determine the frequency with which MRI of tenosynovial giant cell tumor demonstrates hemosiderin, visible intralesional fat signal, and proximity to synovial tissue. MATERIAL AND METHODS: This is a retrospective study of 31 cases of tenosynovial giant cell tumors which had concomitant MRI. Images were examined for lesion size, morphology, origin, bone erosions, MRI signal characteristics, contrast enhancement, and blooming artifact, comparing prospective and retrospective reports. Histology was reviewed for the presence of hemosiderin and xanthoma cells. RESULTS: Eight lesions were diffuse and 23 were localized nodules. Three lesions were located in subcutaneous tissue and 4 adjacent to tendons beyond the extent of their tendon sheath. All lesions exhibited areas of low T1- and T2-weighted signal. Blooming artifact on gradient echo imaging was present in 86% of diffuse and only 27% of nodular disease. There was interobserver variability of 40% in assessing blooming. Iron was visible on H&E or iron stain in 97% of cases. Fat signal intensity was seen in only 3% of cases, although xanthoma cells were present on in 48%. The correct diagnosis was included in the prospective radiology differential diagnosis in 86% of diffuse cases and 62% of nodular cases. CONCLUSION: Blooming on GRE MRI has low sensitivity for nodular tenosynovial giant cell tumors and is not universal in diffuse tumors. There was high interobserver variability in assessment of blooming. Intralesional fat signal is not a useful sign and may occur adjacent to tendons which lack a tendon sheath and may occur in a subcutaneous location.

Pigmented Villonodular Synovitis of the Hip in Patients Undergoing Total Hip Arthroplasty: A Retrospective Case-Controlled Analysis.

BACKGROUND: Pigmented villonodular synovitis (PVNS) is a condition affecting larger joints such as the hip and knee. Little is known regarding the impact of PVNS on total hip arthroplasty (THA). Therefore, the aim of this study is to determine if patients with PVNS of the hip undergoing primary THA experience greater (1) in-hospital lengths of stay (LOS); (2) complications; (3) readmission rates; and (4) costs. METHODS: Patients undergoing primary THA for PVNS of the hip from the years 2005 to 2014 were identified using a nationwide claims registry. PVNS patients were matched to a control cohort in a 1:5 ratio by age, gender, and various comorbidities. The query yielded 7440 patients with (n = 1240) and without (n = 6200) PVNS of the hip undergoing primary THA. Endpoints analyzed included LOS, complications, readmission rates, and costs. Multivariate logistic regression was used to determine odds ratios (OR) of developing complications. Welch's t-tests were used to test for significance in LOS and cost between the cohorts. A P-value less than .001 was considered statistically significant. RESULTS: PVNS patients had approximately 8% longer in-hospital LOS (3.8 vs 3.5 days, P = .0006). PVNS patients had greater odds of (OR 1.60, P < .0001) medical and (OR 1.81, P < .0001) implant-related complications. Furthermore, PVNS patients were found to have higher odds (OR 1.84, P < .0001) of 90-day readmissions. PVNS patients also incurred higher day of surgery ($13,119 vs $11,983, P < .0001) and 90-day costs ($17,169 vs $15,097, P < .0001). CONCLUSION: Without controlling for global trends in LOS, complications, readmissions, or costs between 2005 and 2014, the findings of the study suggest that PVNS of the hip is associated with worse outcomes and higher costs following primary THA. The study is useful as orthopedic surgeons can use the study to educate patients of the complications which may occur following their hip surgery.