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

Diffuse-Type Tenosynovial Giant Cell Tumor: What Are the Important Findings on the Initial and Follow-Up MRI?

Tenosynovial giant cell tumor (TSGCT) is a rare soft tissue tumor that involves the synovial lining of joints, bursae, and tendon sheaths, primarily affecting young patients (usually in the fourth decade of life). The tumor comprises two subtypes: the localized type (L-TSGCT) and the diffuse type (D-TSGCT). Although these subtypes share histological and genetic similarities, they present a different prognosis. D-TSGCT tends to exhibit local aggressiveness and a higher recurrence rate compared to L-TSGCT. Magnetic resonance imaging (MRI) is the preferred diagnostic tool for both the initial diagnosis and for treatment planning. When interpreting the initial MRI of a suspected TSGCT, it is essential to consider: (i) the characteristic findings of TSGCT-evident as low to intermediate signal intensity on both T1- and T2-weighted images, with a blooming artifact on gradient-echo sequences due to hemosiderin deposition; (ii) the possibility of D-TSGCT-extensive involvement of the synovial membrane with infiltrative margin; and (iii) the resectability and extent-if resectable, synovectomy is performed; if not, a novel systemic therapy involving colony-stimulating factor 1 receptor inhibitors is administered. In the interpretation of follow-up MRIs of D-TSGCTs after treatment, it is crucial to consider both tumor recurrence and potential complications such as osteoarthritis after surgery as well as the treatment response after systemic treatment. Given its prevalence in young adult patents and significant impact on patients' quality of life, clinical trials exploring new agents targeting D-TSGCT are currently underway. Consequently, understanding the characteristic MRI findings of D-TSGCT before and after treatment is imperative.

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.

One-Stage Synovectomies Result in Improved Short-Term Outcomes Compared to Two-Stage Synovectomies of Diffuse-Type Tenosynovial Giant Cell Tumor (D-TGCT) of the Knee: A Multicenter, Retrospective, Cohort Study

Diffuse-type tenosynovial giant cell tumors' (D-TGCTs) intra- and extra-articular expansion about the knee often necessitates an anterior and posterior surgical approach to facilitate an extensive synovectomy. There is no consensus on whether two-sided synovectomies should be performed in one or two stages. This retrospective study included 191 D-TGCT patients from nine sarcoma centers worldwide to compare the postoperative short-term outcomes between both treatments. Secondary outcomes were rates of radiological progression and subsequent treatments. Between 2000 and 2020, 117 patients underwent one-stage and 74 patients underwent two-stage synovectomies. The maximum range of motion achieved within one year postoperatively was similar (flexion 123-120°, p = 0.109; extension 0°, p = 0.093). Patients undergoing two-stage synovectomies stayed longer in the hospital (6 vs. 4 days, p < 0.0001). Complications occurred more often after two-stage synovectomies, although this was not statistically different (36% vs. 24%, p = 0.095). Patients treated with two-stage synovectomies exhibited more radiological progression and required subsequent treatments more often than patients treated with one-stage synovectomies (52% vs. 37%, p = 0.036) (54% vs. 34%, p = 0.007). In conclusion, D-TGCT of the knee requiring two-side synovectomies should be treated by one-stage synovectomies if feasible, since patients achieve a similar range of motion, do not have more complications, but stay for a shorter time in the hospital.

MRI of diffuse-type tenosynovial giant cell tumour in the knee: a guide for diagnosis and treatment response assessment

Tenosynovial giant cell tumour (TGCT) is a rare soft-tissue tumour originating from synovial lining of joints, bursae and tendon sheaths. The tumour comprises two subtypes: the localised-type (L-TGCT) is characterised by a single, well-defined lesion, whereas the diffuse-type (D-TGCT) consists of multiple lesions without clear margins. D-TGCT was previously known as pigmented villonodular synovitis. Although benign, TGCT can behave locally aggressive, especially the diffuse-type. Magnetic resonance imaging (MRI) is the modality of choice to diagnose TGCT and discriminate between subtypes. MRI can also provide a preoperative map before synovectomy, the mainstay of treatment. Finally, since the arrival of colony-stimulating factor 1-receptor inhibitors, a novel systemic therapy for D-TGCT patients with relapsed or inoperable disease, MRI is key in assessing treatment response. As recurrence after treatment of D-TGCT occurs more often than in L-TGCT, follow-up imaging plays an important role in D-TGCT. Reading follow-up MRIs of these diffuse synovial tumours may be a daunting task. Therefore, this educational review focuses on MRI findings in D-TGCT of the knee, which represents the most involved joint site (approximately 70% of patients). We aim to provide a systematic approach to assess the knee synovial recesses, highlight D-TGCT imaging findings, and combine these into a structured report. In addition, differential diagnoses mimicking D-TGCT, potential pitfalls and evaluation of tumour response following systemic therapies are discussed. Finally, we propose automated volumetric quantification of D-TGCT as the next step in quantitative treatment response assessment as an alternative to current radiological assessment criteria.