Synovial Sarcoma of the Thyroid Gland, Diagnostic Pitfalls and Clinical Management

Synovial sarcoma is a soft tissue sarcoma that tends to affect young adults. There are few reports on primary synovial sarcoma of the thyroid and the aim of this study was to document the clinical and pathological features of synovial sarcoma occurring at this site.

A retrospective review of a prospectively maintained database was performed to identify patients with synovial sarcoma of the thyroid treated at the Royal Marsden Hospital between 2000 and 2017. Five patients were identified that underwent initial surgical management of localized disease. The mean age at presentation was 38 years, and male to female ratio was 4:1. In 3 out of 5 cases, the diagnosis of synovial sarcoma was made on the post-operative excision specimen. Two of these patients were treated at our institution on the development of metastatic disease. We conducted a literature review and identified 12 previously reported cases of synovial sarcoma of the thyroid.

Synovial sarcoma of the thyroid is rare and can be challenging to diagnose. The clinical presentation is typically indistinguishable from that of thyroid cancer and most cases are diagnosed post-operatively on an excision specimen. The clinical and pathological features are similar to synovial sarcoma arising at other sites. In our experience, the rarity of the diagnosis can lead to difficulty in establishing the correct diagnosis and determining the appropriate treatment pathway. It is important that physicians are aware of this diagnosis to facilitate prompt referral to a specialist centre, for specialist follow-up and treatment which is different to the thyroid cancer pathway.