Tenosynovial giant cell tumour in children. Our experience with 24 patients in a third level Children's Hospital, an...

Tenosynovial giant cell tumour (TGCT) is a benign fibrohistiocytic proliferation that can lead to intraarticular inflammation causing secondary degenerative arthropathy. Surgery is the preferred treatment to avoid complications. Paediatric TGCT is rarely reported, mostly in case studies. This revision presents the largest paediatric series. This observational study involved 24 paediatric patients reported between 1998 and 2023 with confirmed histological diagnosis of TGCT. Descriptive statistics were used for analysis. Twenty-four patients (mean age 12.25 years, SD 3.78; 1:1 gender ratio) were included with the anatomopathological diagnosis of TGCT. The knee was the most affected joint (75%), with localized nodular presentation (66.7%). Initial symptoms were mechanical pain in all patients, joint effusion in 79.1%, and limp in 25%. Mean duration of symptom duration before diagnosis was 9 months (range 4-15). Magnetic Resonance Imaging (MRI) findings were consistent with TGCT in all cases, and alter confirmed by arthroscopic biopsy. Radiographs showed soft tissue changes in five patients. Treatment included arthroscopic synovectomy (70.8%) or open surgery (29.2%). Over a mean follow-up of 98 months (range 6-288), six recurrences occurred, all with diffuse presentation at the knee.

MRI is the preferred method for diagnosis and follow-up. Surgery is the main treatment, with low recurrence if nodular lesions are accurately removed. Outcomes and recurrence depend on diffuse presentation. We recommend open surgery for recurrences and local adjuvant treatment.

• Tenosynovial Giant Cell Tumour (TGCT) is an uncommon benign synovial lesion usually described as isolated case reports in children. • MRI is the preferred imaging technique due its superior tissue contrast and ability to differentiate diffuse and localized forms.

• We present the largest known pediatric series of TGCT including 24 histolgically confirmed cases and with outcome data. • The study provides insight into recurrence patterns and supports a tailored surgical approach based on lesion type.