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

Pigmented villonodular synovitis/giant cell tumor in the knee

PURPOSE OF REVIEW

Pigmented villonodular synovitis (PVNS) is a rare diagnosis in pediatric patients and commonly presents with symptoms of swelling and pain. Early diagnosis is important to prevent secondary degeneration into the subchondral bone. This review will analyze the etiology, clinical signs/symptoms, diagnosis, treatment, and recent literature on PVNS in the pediatric population.

RECENT FINDINGS

Many theories of PVNS etiology have been described in the literature; however, an inflammatory response has been most widely accepted. PVNS can occur in any joint, but most commonly in the knee. The most common treatment for PVNS is synovectomy, and long-term follow-up is necessary to detect disease persistence or recurrence.

SUMMARY

Although uncommon, PVNS does occur in the pediatric population and this diagnosis should be included in the differential of atraumatic joint swelling and pain.

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.

Arthroscopic Excision of a Localized Tenosynovial Giant Cell Tumor of the Knee: A Case Report

BACKGROUND AND AIM

A tenosynovial giant cell tumor (TGCT) is a proliferative lesion of the synovial membrane of the joints, tendon sheaths and/or bursae. There are two described subtypes, including the localized and diffuse forms. A TGCT can also be intraarticular or extraarticular. An intraarticular localized tenosynovial giant cell tumor (L-TGCT) of the knee is characterized by nodular hyperplasic synovial tissue that can remain asymptomatic for a long time, but as the mass grows, it may cause mechanical symptoms that may require surgical treatment. The aim of our study is to present a rare case of an L-TGCT of the knee joint treated with an arthroscopic excision.

CASE REPORT

We describe the case of a 17-year-old female with pain, swelling and knee locking in the absence of trauma. The magnetic resonance imaging (MRI) displayed a well-circumscribed small mass in the anterior medial compartment, adherent to the infrapatellar fat pad. The lesion presented the typical MRI characteristics of an intraarticular localized TGCT. The patient was treated with an arthroscopic mass removal and partial synovectomy. The gross pathology showed an ovoid nodule that was covered by a fibrous capsule; a histopathology examination confirmed the diagnosis. The patient was able to return to normal daily activities one month after surgery; at the three-year follow-up, she was free of symptoms with no evidence of disease on the MRI.

CONCLUSION

In patients with a small-dimension L-TGCT in the anterior compartment of the knee that presents an MRI pattern and causes mechanical symptoms, an arthroscopic en-bloc excision can be performed that results in good outcomes and a rapid return to preinjury levels.

Localized tenosynovial giant cell tumor in children

Background

To investigate the clinical characteristics and surgical efficacy of localized tenosynovial giant cell tumors in children.

Methods

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.

Results

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.

Conclusion

Extremities are common sites of localized tenosynovial giant cell tumors in children. Complete surgical resection helps reduce the recurrence rate.

Level of evidence

Level III.

Pitfalls of Diffusion-Weighted Imaging: Clinical Utility of T2 Shine-through and T2 Black-out for Musculoskeletal Diseases

Diffusion-weighted imaging (DWI) with an apparent diffusion coefficient (ADC) value is a relatively new magnetic resonance imaging (MRI) sequence that provides functional information on the lesion by measuring the microscopic movement of water molecules. While numerous studies have evaluated the promising role of DWI in musculoskeletal radiology, most have focused on tumorous diseases related to cellularity. This review article aims to summarize DWI-acquisition techniques, considering pitfalls such as T2 shine-through and T2 black-out, and their usefulness in interpreting musculoskeletal diseases with imaging. DWI is based on the Brownian motion of water molecules within the tissue, achieved by applying diffusion-sensitizing gradients. Regardless of the cellularity of the lesion, several pitfalls must be considered when interpreting DWI with ADC values in musculoskeletal radiology. This review discusses the application of DWI in musculoskeletal diseases, including tumor and tumor mimickers, as well as non-tumorous diseases, with a focus on lesions demonstrating T2 shine-through and T2 black-out effects. Understanding these pitfalls of DWI can provide clinically useful information, increase diagnostic accuracy, and improve patient management when added to conventional MRI in musculoskeletal diseases.