Localized Tenosynovial Giant Cell Tumor Research Articles

Cytoplasmic PPARγ Significantly Correlates With P53 Immunohistochemical Expression and Tumor Size in Localized Tenosynovial Giant Cell Tumor.

Tenosynovial giant cell tumor (TGCT)is a monoarticular fibrohistiocytic benign or locally aggressive soft tissue tumor that originates from the synovium of joints, bursae, and tendon sheaths.It has an inflammatory neoplastic nature, with a clinical presentationranging from pain, swelling, stiffness, and limited range of movement to joint instability and blockage. Its uncommon incidence leads to a poorly understood pathogenesis. Localized formsof TGCT (LTGCT) can cause significant morbidity, interfere with daily patient activities, and decrease the patient's quality of life in challenging cases. This study aimed to investigate the immunohistochemical expression of PPARγ (peroxisome proliferator-activated receptor gamma) and P53 in LTGCT to understand the disease better and offer potential therapeutic targets. The study is cross-sectional, in which 27 LTGCT cases were collectedfrom the Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt.Solitary and multiple LTGCT cases retrieved between January 2018 and December 2022 were included, and immunohistochemically stained with anti-PPARγ and P53 antibodies. The TGCT samples were excluded if they were insufficient for sectioning, processing, and interpretation, over-fixed, had process artifacts, or were of the diffuse TGCT type. Scoring of stain expression was performed by ImageJ (National Institutes of Health, Bethesda, MD) analysis using the threshold method and was expressed in percent area/high power field. Clinicopathological correlations were analyzed. All the 27 collected LTGCT cases were located in the small joints of patients' hands. Cases with solitary LGTCTs constituted 55.6%(n = 15), while 44.4% (n = 12) had multipleLTGCTs related to one affected site/case (e.g., multiple tumors in one finger). PPARγ was expressed in the cytoplasm of mononuclear and multinucleated tumor cells and foamy histiocytes, while P53 expression was mainly in mononuclear cells' nuclei. PPARγ significantly correlated with P53 expression (r = 0.9 and P = 0.000). PPARγ (r = 0.4 and P = 0.02) and P53 (r = 0.5 and P = 0.01) were positively correlated with tumor size. Only P53 expression was positively correlated with tumor multiplicity (r = 0.4 and P = 0.03). Using the receiver operating characteristic curve test, the P53 cutoff score detecting the multiplicity of TGCTs was ≥20.5%, with a 75% sensitivity and 80% specificity. PPARγ and P53 have a significant role in LTGCT growth, while P53 plays a role in tumor multiplicity. They can be possible targets in LTGCTs unfit for excision.

Imaging characteristics of tenosynovial giant cell tumors on 18F-fluorodeoxyglucose positron emission tomography/computed tomography: a retrospective observational study

Background18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) is useful for assessing location, metastasis, staging, and recurrence of malignant tumors. Tenosynovial giant cell tumor (TSGCT) is a benign tumor; however, some studies have reported that TSGCTs have a high uptake of FDG. Few studies have reported on the detailed evaluation of TSGCT using 18F-FDG-PET/CT. The purpose of the current study is to evaluate the image characteristics and locations, particularly where possible, with or without, extra-articular invasion from TSGCT of the knee in 18F-FDG-PET/CT could occur.MethodsWe retrospectively reviewed the patients with TSGCT who were diagnosed pathologically either by biopsy or surgical specimen. Furthermore, we evaluated the difference of the maximum standardized uptake value (SUVmax) between diffused TSGCT with extra-articular invasion and TSGCT with intra-articular localization in the knee.ResultsThe study consisted of 20 patients with TSGCT. The mean SUVmax of TSGCT was 12.0 ± 6.50. There were five patients with TSGCT arising in the knee with extra-articular invasion and six with TSGCT with intra-articular localization. The mean SUVmax of TSGCT with extra-articular invasion and those with intra-articular localization were 14.3 ± 6.00 and 5.94 ± 3.89, respectively. TSGCT with extra-articular invasion had significantly higher SUVmax than TSGCT with intra-articular localization (p < 0.05).ConclusionsTSGCT revealed high FDG uptake. Furthermore, SUVmax was higher in diffused TSGCT with extra-articular invasion than in intra-articular localized TSGCT; this may reflect its local aggressiveness.

Localized tenosynovial giant cell tumor in children.

To investigate the clinical characteristics and surgical efficacy of localized tenosynovial giant cell tumors in children. The clinical data, surgery, and follow-up results of 17 children with localized tenosynovial giant cell tumors who visited our hospital from 2011 to 2021 were collected for statistical analysis. The median patient age was 7 years and 8 months, and the ratio of males to females was 1.43 (10/7). The predilection of disease was similar in hands and feet, and the common presenting symptom was mass. One patient experienced recurrence after surgery, and one child had postoperative functional limitations. Extremities are common sites of localized tenosynovial giant cell tumors in children. Complete surgical resection helps reduce the recurrence rate. Level III.

A phase 2, open-label, adaptive, dose-ranging study with long-term extension to evaluate the safety, tolerability, efficacy, and pharmacokinetics of intra-articular AMB-05X injections in patients with tenosynovial giant cell tumor.

TPS11585 Background: CSF1R is a clinically validated target for Tenosynovial Giant Cell Tumor (TGCT). CSF1 is overexpressed in TGCT and, via action at the colony-stimulating factor 1 receptor (CSF1R), leads to the proliferation of synovial-like mononuclear cells and recruitment of multinucleate giant cells, foam cells, siderophages, and inflammatory cells, which compose the bulk of the neoplasm. Although nonmetastatic in nature, TGCT can develop into locally destructive lesions that cause significant local tissue injury, loss of joint function, and impaired quality of life. When complete resection is achievable without significant morbidity, the standard of care for patients with TGCT is surgical resection. Recurrence after surgery occurs in up to 30% of patients with localized TGCT and 83% of patients with diffuse TGCT ( Mastboom 2019, Patel 2017). Repeat surgeries may be necessary but often leads to further morbidity, complications, and reduced function of affected joints. A safe, effective, and convenient pharmacotherapy is a desirable addition to the therapeutic armamentarium for TGCT. AMB-05X is a potent and selective anti-CSF1R monoclonal antibody in development for local treatment of TGCT. Intra-articular (IA) injection of AMB-05X enables high drug concentration at the tumor site while minimizing systemic exposure and toxicity. A proof-of-concept study of IA AMB-05X for TGCT found clinically meaningful improvement in objective response rate, functional (pain, stiffness, range of motion) and quality of life measures after 12 weeks of therapy with no serious and a low number of adverse events associated with targeting CSF1R. This phase 2 study aims to establish the optimal dosing regimen and local administration of AMB-05X and confirm the efficacy and safety of 24 weeks and longer treatment. Methods: AMB-051-07 (NCT05349643) is an open-label, multicenter, phase 2 study of AMB-05X in patients with TGCT. The trial is being conducted at multiple sites in North America, Europe, and Australia. The dosing schedule includes an injection interval of every 4 weeks and longer, including an extended dosing period. Adult patients with histologically confirmed symptomatic TGCT with one joint involvement whether surgically amenable or non-amenable with measurable disease and adequate organ function are being enrolled. After the initial cohort of patients with TGCT of the knee, other joints may be enrolled pending evaluation by the DMC. The primary study outcome measures are objective response rate (ORR) per RECIST v1.1 by central radiology review and safety. Secondary outcome measures include ORR per modified RECIST and Tumor Volume Score, duration of response, time to response, PRO/QOL (including range of motion, stiffness, pain), pharmacodynamics and pharmacokinetics. Clinical trial information: NCT05349643 .

Arthroscopic resection of localized tenosynovial giant cell tumor in the deep infrapatellar bursa: a case report

Tenosynovial giant cell tumor (TGCT) is a rare disease characterized by the proliferation of the synovial membrane of a joint, tendon sheath, or bursa. TGCTs in joints are subdivided into the diffuse or localized type. The localized TGCT most frequently affects the knee and may occur in any knee compartment. The most common localization is the Hoffa’s fat pad, followed by the suprapatellar pouch and the posterior capsule. Here, we describe a case of a histopathologically proven TGCT of the knee, found in an unusual localization in the deep infrapatellar bursa, which was diagnosed by magnetic resonance imaging. The tumor was entirely arthroscopically resected. The patient had no further complaints following the operation, and there was no recurrence at the 18-month follow-up. Even though TGCT of the knee is uncommon, it should not be overlooked by orthopedic and trauma surgeons, and excision should be regarded as a reliable treatment option. The form of surgical treatment, either open or arthroscopic, should be determined based on a combination of the surgeon's preference and the best approach to the anatomical location of the disease.

Effectiveness of arthroscopic excision based on the distribution of the tenosynovial giant cell tumor around knee joint

BackgroundThe mainstay treatment for tenosynovial giant cell tumor (TGCT) is open excision. However, open excision is associated with the risk of stiffness, infection, neurovascular injury, and prolonged hospital stay and rehabilitation. The purpose of this study was to evaluate the efficacy of arthroscopic excision of tenosynovial giant cell tumor (TGCT) of the knee joint, including the diffuse type of TGCT. MethodsPatients who underwent arthroscopic excision of TGCT between April 2014 and November 2020 were retrospectively analyzed. TGCT lesions were divided into 12 distributions (nine intra- and three extra-articular lesions). The distribution of TGCT lesions, portals used, degree of excision, recurrence, and magnetic resonance imaging (MRI) scans were evaluated. The prevalence of intra-articular lesions in diffuse TGCT was also analyzed to validate the existence of a connection between intra- and extra-articular lesions. ResultsTwenty-nine patients were included in the study. Fifteen patients (52%) had localized TGCT, and 14 patients (48%) had diffuse TGCT. The recurrence rates for localized, and diffuse TGCT were 0%, and 7%, respectively. Intra-articular posteromedial (i-PM), intra-articular posterolateral (i-PL), and extra-articular posterolateral (e-PL) lesions were found in all patients with diffuse TGCT. The prevalence rates of i-PM and i-PL lesions among e-PL lesions were both 100% (p = 0.026 and p < 0.001, respectively). Diffuse TGCT lesions were managed with posterolateral capsulotomy and viewed from the trans-septal portal. ConclusionsArthroscopic excision of TGCT was effective in both localized and diffuse TGCT. However, diffuse TGCT was associated with posterior and extra-articular lesions. Therefore, technical modification such as posterior, trans-septal portal, and capsulotomy were required. Study designRetrospective case series; level Ⅳ.

FNAC study of giant cell tumor of tendon sheath (localized tenosynovial giant cell tumor): Clinico-radiological correlation and cytopathological features.

Localized tenosynovial giant cell tumor (GCT) or giant cell tumor of tendon sheath (GCTTS), is a benign nodular lesion that arises from the synovium of the tendon sheath of the hands and foot. GCTTS is characterized by the presence of multinucleated giant cells and proliferation of synovial-like mononuclear cells. A clinical diagnosis of GCTTS is kept as a differential when a firm, nodular mass shows decreased signal intensity on both T1-and T2-weighted MR imaging. Treatment is usually marginal excision of the mass. It is a retrospective study, observed in the past 3 years at a tertiary care hospital. Those cases were included in the study in which histopathological confirmation was available or if clinico-radiological features were confirmatory of the diagnosis of GCTTS when correlated with cytological features. There was a total of 24 cases, out of which 16 were females and 8 males. The tumor was located in the upper limb in 21 cases and in 3 cases the tumor was present in the lower limb. In the upper limb, 18 cases were on the right side and three cases were on the left side. In the lower limb, 1 case was present on the left and 2 on the right side. The cytomorphology consisted of mononuclear stromal cells, multinucleated giant cells, and hemosiderin-laden macrophages in variable numbers. It is important to accurately diagnose and categorize giant cell-containing lesions because their prognosis depends on the exact categorization of the tumor.

Chondroid tenosynovial giant cell tumor of the temporomandibular joint presenting as a deep-lobe parotid tumor

Tenosynovial giant cell tumor (TGCT) is a rare benign craniofacial soft-tissue tumor characterized by overgrowth of the synovial tissue, tendon sheath, bursa, and joint structure. It is classified into two types, diffuse and localized TGCT, and has rarely been reported in the temporomandibular joint. The etiology of TGCT is unknown, and the management of TGCT varies depending on the tumor location and treatment-related morbidity. Here, we describe the case of a 47-year-old man who presented with a complaint of a right parotid mass that had slowly increased over 2 months and was associated with ear fullness. Initially, the lesion was painless, but pain during chewing without any limitation of the jaw movement developed subsequently. The patient was diagnosed with diffuse TGCT with chondroid metaplasia.

A New Simple and Practical Clinical Classification for Tenosynovial Giant Cell Tumors of the Knee.

ObjectiveTo propose a simple and practical clinical classification for tenosynovial giant cell tumor (TGCT) of the knee.MethodsA retrospective study was conducted to verify the value and significance of this clinical classification. TGCT growth patterns, knee joint capsule, and bone erosion were applied to establish this novel clinical classification. Seventy‐eight patients who underwent surgery for TGCT from 2008 to 2016 were identified. This novel clinical classification was retrospectively applied to patients' existing classification, and patients with different TGCT types were statistically compared to verify the significance of the clinical classification.ResultsThe clinical classification included three types and four subtypes. Type 1: localized TGCT, Subtype 1a: localized intra‐articular TGCT, Subtype 1b: localized extra‐articular TGCT. Type 2: diffuse TGCT, Subtype 2a: diffuse intra‐articular TGCT with bone normal, Subtype 2b: diffuse intra‐articular TGCT with bone destruction. Type 3: diffuse TGCT across the knee joint capsule. The mean follow‐up time for the 78 patients was 59.6 months. Twenty‐one patients were in Subtype 1a, four were Subtype 1b, 38 were Subtype 2a, seven were Subtype 2b, and eight were Type 3. Oncological results and surgical complications differed significantly (P = 0.000, P = 0.000). The mean Musculoskeletal Tumor Society functional scores differed significantly at 27.8 for Type 1 patients, 22.9 for Type 2 patients, and 17.0 for Type 3 patients (P = 0.000).ConclusionsThis clinical classification can be easily used to evaluate TGCT of all knees prior to surgery or other treatments and can help determine surgical options.

Tenosynovial Giant Cell Tumor in the Hand: Experience with 173 Cases.

Background: Tenosynovial giant cell tumor (TSGCT) is the second most common benign tumor of the hand. Even though it is a benign lesion there is still a high incidence of local recurrence (range, 7%-44%) according to data in published papers. In this study, the clinical and epidemiological features of 173 patients who underwent excision of localized TSGCT, the recurrence rates and possible reasons for recurrence were examined in the light of current literature. Methods: Medical records of 173 patients with TSGCT were reviewed. Data on demographic characteristics as well as clinical and intraoperative findings were collected. Patients were asked about the recurrence of the TSGCT and the QuickDASH scoring was applied at the final clinical evaluation after mean follow-up of 81 months. Results: Females were predominantly involved (73%). Patients aged mean 44 years at the time of surgery. There were 93 tumors in flexor zones and 80 tumors in extensor zones of the hand. Of the tumors with flexor zone localization, zone II was most predominantly involved with 46 tumors, and 18 of these were on the index finger. The extensor zones III and IV were mostly involved with 9 tumors each on the middle and ring fingers. A total of 12 recurrences (6.9 %) were determined over the mean follow-up period of 81 months. Conclusions: The characteristics of our patients identified were similar to the previous studies. Surgical excision provides good outcomes in the treatment of TSGCT especially when clear margins are obtained.

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.

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

Randomized placebo-controlled double-blind phase II study of zaltoprofen for patients with diffuse-type and unresectable localized tenosynovial giant cell tumors: a study protocol

BackgroundA tenosynovial giant cell tumor (TGCT) is a locally aggressive benign neoplasm arising from intra- or extra-articular tissue. Diffuse TGCT (D-TGCT) most commonly develops in the knee, followed by the hip, ankle, elbow, and shoulder. Surgical removal is the only effective treatment option for the patients. However, a local recurrence rate as high as 47% has been reported. Recently, we revealed that zaltoprofen, a nonsteroidal anti-inflammatory drug possessing the ability to activate peroxisome proliferator-activated receptor gamma (PPARγ), can inhibit the proliferation of TGCT stromal cells via PPARγ. PPARγ is a ligand-activated transcription factor that belongs to the nuclear hormone receptor superfamily. It plays an important role in the differentiation of adipocytes from precursor cells and exhibits antitumorigenic effects on certain malignancies. Therefore, we are conducting this investigator-initiated clinical trial to evaluate whether zaltoprofen is safe and effective for patients with D-TGCT or unresectable localized TGCT (L-TGCT).MethodsThis study is a randomized, placebo-controlled, double-blind, multicenter trial to evaluate the safety and efficacy of zaltoprofen for patients with D-TGCT or L-TGCT. For the treatment group, zaltoprofen 480 mg/day will be administered for 48 weeks; the placebo group will receive similar dosages without zaltoprofen. Twenty participants in each group are needed in this trial (40 participants total). The primary outcome is the progression-free rate at 48 weeks after treatment administration. “Progression” is defined as any serious events (1. Repetitive joint swelling due to hemorrhage, 2. Joint range of motion limitation, 3. Invasion of adjacent cartilage or bone, 4. Severe joint space narrowing, 5. Increase in tumor size) requiring surgical interventions. We hypothesize that the zaltoprofen group will have a higher progression-free rate compared to that of the placebo group at 48 weeks.DiscussionThis is the first study to evaluate the efficacy of zaltoprofen in patients with D-TGCT or unresectable L-TGCT. We believe that the results of this trial will validate a novel treatment option, zaltoprofen, to stabilize disease progression for TGCT patients.Trial registrationUniversity Hospital Medical Information Network (UMIN) Clinical Trials Registry (UMIN000025901) registered on 4/01/2017.

A Case of Infarcted Localized Tenosynovial Giant Cell Tumor of the Knee: Multimodality Imaging Features and Literature Review

: Localized tenosynovial giant cell tumor (L-TGCT), formerly called giant cell tumor of the tendon sheath, is one of the benign proliferative diseases of the synovium of a joint, bursa, or tendon sheath. L-TGCT occasionally involves a large joint such as the knee, and rarely it is combined with infarction by pedicle torsion. Neither the prevalence of torsion of L-TGCT nor the mechanism involved are known, but it is thought to be uncommon progress. Herein, we describe a rare case of infarcted L-TGCT in the knee involving torsion of a mass pedicle in a 47-year-old man. We utilized magnetic resonance imaging including diffusion-weighted imaging and axial apparent diffusion mapping, and sonographic appearance during the course of investigations, because radiologic findings showed characteristic features of infarcted L-TGCT.

The Patient Perspective on the Impact of Tenosynovial Giant Cell Tumors on Daily Living: Crowdsourcing Study on Physical Function and Quality of Life.

BackgroundTenosynovial giant cell tumor (TGCT) is a rare, benign lesion affecting the synovial lining of joints, bursae, and tendon sheaths. It is generally characterized as a locally aggressive and often recurring tumor. A distinction is made between localized- and diffuse-type. The impact of TGCT on daily living is currently ill-described.ObjectiveThe aim of this crowdsourcing study was to evaluate the impact of TGCT on physical function, daily activities, societal participation (work, sports, and hobbies), and overall quality of life from a patient perspective. The secondary aim was to define risk factors for deteriorated outcome in TGCT.MethodsMembers of the largest known TGCT Facebook community, PVNS is Pants!!, were invited to an e-survey, partially consisting of validated questionnaires, for 6 months. To confirm disease presence and TGCT-type, patients were requested to share histological or radiological proof of TGCT. Unpaired t tests and chi-square tests were used to compare groups with and without proof and to define risk factors for deteriorated outcome.ResultsThree hundred thirty-seven questionnaires, originating from 30 countries, were completed. Median age at diagnosis was 33 (interquartile range [IQR]=25-42) years, majority was female (79.8% [269/337]), diffuse TGCT (70.3% [237/337]), and affected lower extremities (knee 70.9% [239/337] and hip 9.5% [32/337]). In 299 lower-extremity TGCT patients (32.4% [97/299]) with disease confirmation, recurrence rate was 36% and 69.5% in localized and diffuse type, respectively. For both types, pain and swelling decreased after treatment; in contrast, stiffness and range of motion worsened. Patients were limited in their employment (localized 13% [8/61]; diffuse 11.0% [21/191]) and sport-activities (localized 58% [40/69]; diffuse 63.9% [147/230]). Compared with general US population, all patients showed lower Patient-Reported Outcomes Measurements Information System-Physical Function (PROMIS-PF), Short Form-12 (SF-12), and EuroQoL 5 Dimensions 5 Levels (EQ5D-5L) scores, considered clinically relevant, according to estimated minimal important difference (MID). Diffuse versus localized type scored almost 0.5 standard deviation lower for PROMIS-PF (P<.001) and demonstrated a utility score of 5% lower for EQ-5D-5L (P=.03). In localized TGCT, recurrent disease and ≥2 surgeries negatively influenced scores of Visual Analog Scale (VAS)-pain/stiffness, SF-12, and EQ-5D-5L (P<.05). In diffuse type, recurrence resulted in lower score for VAS, PROMIS-PF, SF-12, and EQ-5D-5L (P<.05). In both types, patients with treatment ≤1year had significantly lower SF-12.ConclusionsTGCT has a major impact on daily living in a relatively young and working population. Patients with diffuse type, recurrent disease, and ≥2 surgeries represent lowest functional and quality of life outcomes. Physicians should be aware that TGCT patients frequently continue to experience declined health-related quality of life and physical function and often remain limited in daily life, even after treatment(s).

Chondroid tenosynovial giant cell tumor of the toe: A case report

Localized tenosynovial giant cell tumor (TGCT) usually occurs in the hand and foot regions. However, localized TGCT with extensive cartilaginous metaplasia is rare, especially in the tendon sheath of the toe. Here, we report a case of localized TGCT with cartilaginous metaplasia in a 57-year-old man. The tumor presented as a lobular mass measuring 2.2 cm in its greatest dimension and arose in the flexor digitorum tendon sheath of the right 2nd toe. Clinically, the mass was palpable 1 year ago and brought pain during walking. Microscopically, the mass was composed of focal conventional TGCT and cartilaginous components. The conventional TGCT areas consisted of mononuclear cells, multinucleated giant cells, and hemosiderin deposition. The chondroid areas were extensive and comprised more than 90% of the whole tumor. In this case, the mononuclear cells in the conventional TGCT areas showed focal immunohistochemical staining for podoplanin and S100 protein as well as diffuse staining for CD68, which is consistent with the staining pattern of conventional TGCT. The mononuclear cells in the chondroid areas were focal positive for podoplanin and diffuse positive for S100 protein. Chondroid metaplasia in diffuse TGCT has been reported in 10 cases involving the temporomandibular, elbow, and hip joints. However, there has been no report of a localized form of chondroid TGCT involving an extra-articular region.

Intra-articular synovial sarcoma

A case of right knee intra-articular synovial sarcoma in a 26-year-old man is reported. The patient had experienced 12 to 18 months of chronic posterior right knee pain with flexion contracture of the leg. Magnetic resonance imaging (MRI) examination demonstrated nonspecific characteristics of a well-circumscribed, homogeneous mass within the posterior lateral compartment of the knee joint. The mass was isointense and hyperintense to muscle on T1- and T2-weighted sequences respectively, and initially clinically diagnosed as a localized tenosynovial giant cell tumor. However, histological examination showed the lesion to be a synovial sarcoma arising from the synovium of the knee joint. Synovial sarcoma may have a nonspecific MR appearance, especially when less than 5 cm in size, often simulating a less aggressive process. Primary intra-articular origin may predispose to earlier presentation, and therefore, radiological evaluation of smaller masses. Nonspecific MR characteristics of small, intra-articular masses provide a diagnostic dilemma. Synovial sarcoma should be considered in the differential diagnosis when distinguishing MR characteristics of other common joint-centered entities are not present.

Tenosynovial Giant Cell Tumor: Case Report and Review

Tenosynovial giant cell tumors are a group of generally benign intra-articular and soft tissue tumors with common histologic features. They can be roughly divided into localized and diffuse types. Localized types include giant cell tumors of tendon sheath and localized pigmented villonodular synovitis, whereas diffuse types encompass conventional pigmented villonodular synovitis and diffuse-type giant cell tumor. Localized tumors are generally indolent, whereas diffuse tumors are locally aggressive. Recent developments indicate that tenosynovial giant cell tumors are clonal neoplastic tumors driven by overexpression of CSF1. Herein, I report a case of intra-articular, localized tenosynovial giant cell tumor (or localized pigmented villonodular synovitis) and review the classification, histopathology, and recent developments regarding its pathogenesis.

A Case of Localized Tenosynovial Giant Cell Tumor in the Infrapatellar Fat Pad of the Knee

Localized giant cell tumor of the tendon sheath (GCTTS) usually occurs in extensor an tendon sheath of the fingers and toes. It has rarely been observed in the fat pad of the knee joint. We treated a case of a 2.5×3×4 cm mass arising from the infrapatellar fat pad, which presented with extension limitation and knee pain due to lateral femorotibial joint impingement. The tumor was successfully treated using arthroscopic excision with a motorized shaver. Histologic findings were diagnosed as localized GCTTS. Herein we report this case with a literature review.

Localized tenosynovial giant cell tumor in both knee joints

Tenosynovial giant cell tumor, previously called pigmented villonodular synovitis (PVNS), is a rare benign neoplastic process that may involve the synovium of the joint. The disorder is usually monoarticular and only a few cases have been reported on polyarticular involvement. Herein, we present a case of localized intra-articular tenosynovial giant cell tumor in a 29-year-old man involving both knee joints with a description of the MR imaging and histological findings.

Diffuse and localized tenosynovial giant cell tumor and pigmented villonodular synovitis: A clinicopathologic and flow cytometric DNA analysis

The DNA content and proliferative indexes of seven cases of tenosynovial giant cell tumor of tendon sheath, diffuse type (TGCT-D); 11 cases of tenosynovial giant cell tumor of tendon sheath, localized type (TGCT-L); and seven cases of pigmented villonodular synovitis (PVNS) were analyzed by flow cytometry in an attempt to assess objectively their biologic differences. Three cases of TGCT-D manifested an aneuploid DNA content and four had a diploid DNA pattern. All cases of TGCT-L and PVNS showed a diploid DNA content. The proliferative indexes for TGCT-D were significantly higher than those found in the other two groups. There was no histopathologic feature that correlated with the aneuploid DNA pattern found in two of the three cases of TGCT-D. Only one of the three aneuploid DNA content TGCT-D cases displayed marked cellular pleomorphism with dense fibrous stroma; in that case there was recurrence 4 years after initial excision. Our data further support that TGCT-D, TGCT-L, and PVNS are histopathologically similar but clinically distinct lesions. The high proliferative indexes of TGCT-D may reflect a rapid, uncontrolled growth that may explain its aggressive biologic behavior. The presence of an aneuploid DNA pattern in some cases of TGCT-D in this study, coupled with the reported chromosomal abnormalities and occurrence of malignant transformation in these lesions, clearly supports their neoplastic nature.