Giant cell tumours (GCT) of the synovium and tendon sheath can be classified into two forms: localised (giant cell tumour of the tendon sheath, or nodular tenosynovitis) and diffuse (diffuse-type giant cell tumour or pigmented villonodular synovitis). The former principally affects the small joints. It presents as a solitary slow-growing tumour with a characteristic appearance on MRI and is treated by surgical excision. There is a significant risk of multiple recurrences with aggressive diffuse disease. A multidisciplinary approach with dedicated MRI, histological assessment and planned surgery with either adjuvant radiotherapy or systemic targeted therapy is required to improve outcomes in recurrent and refractory diffuse-type GCT.

Although arthroscopic synovectomy through several portals has been advocated as an alternative to arthrotomy, there is a significant risk of inadequate excision and recurrence, particularly in the posterior compartment of the knee. For local disease partial arthroscopic synovectomy may be sufficient, at the risk of recurrence. For both local and diffuse intra-articular disease open surgery is advised for recurrent disease. Marginal excision with focal disease will suffice, not dissimilar to the treatment of GCT of tendon sheath. For recurrent and extra-articular soft-tissue disease adjuvant therapy, including intra-articular radioactive colloid or moderate-dose external beam radiotherapy, should be considered.

We have analysed the pattern of symptoms in patients presenting with synovial sarcoma to identify factors which led to long delays in diagnosis. In 35 children, the early symptoms and the results of clinical and radiological investigation were reviewed, along with the presumed diagnoses. The duration of symptoms was separated into patient delay and doctor delay.

Only half of the patients had one or more of the four clinical findings suggestive of sarcoma according to the guidance of the National Institute for Clinical Excellence at the onset of symptoms. Of the 33 children for whom data were available, 16 (48.5%) presented with a painless mass and in ten (30.3%) no mass was identified. Seven (21.2%) had an unexplained joint contracture. Many had been extensively investigated unsuccessfully. The mean duration of symptoms was 98 weeks (2 to 364), the mean patient delay was 43 weeks (0 to 156) and the mean doctor delay was 50 weeks (0 to 362). The mean number of doctors seen before referral was three (1 to 6) and for 15 patients the diagnosis was obtained after unplanned excision. Tumours around the knee and elbow were associated with a longer duration of symptoms and longer doctor delay compared with those at other sites. Delays did not improve significantly over the period of our study of 21 years, and we were unable to show that delay in diagnosis led to a worse prognosis.

Our findings highlight the variety of symptoms associated with synovial sarcoma and encourage greater awareness of this tumour as a potential diagnosis in childhood.