MR Imaging Features of Malignant Tenosynovial Giant Cell Tumors

To examine MRI characteristics of malignant tenosynovial giant cell tumors (TSGCTs) and elucidate features to differentiate benign and malignant TSGCTs.

With IRB approval, the medical record was retrospectively reviewed from 2004-2024 for cases of pathologically-proven benign and malignant TSGCTs evaluated by MRI.

12 malignant TSGCTs (5F/7M, mean age 48.7 +/- 17.6 years) and 23 benign TSGCTs (13F/10M, mean age 43.7 +/- 18.7 years) were identified. There was no significant difference in age (p=0.45), gender (p=0.63), MRI signal characteristics (T1 signal p=0.57, T2 signal p=0.46, T2 signal heterogeneity p>0.99, presence of low T2 signal p>0.99), type of enhancement (presence of enhancement p=0.21, degree of enhancement p=0.12, heterogenous vs. homogenous enhancement p=0.21, presence of non-enhancing areas p=0.11), blooming artifact (p=0.065), or presence of perilesional edema (p=0.16) between benign and malignant TSGCTs. Four MRI features were more commonly associated with malignant TSGCTs: extra-articular location (p=0.009), irregular margins (p=0.0014), perilesional vessels (p=0.0014), and larger average maximal dimension (8.6 +/- 8.4 cm malignant vs. 2.8 +/- 2.2 cm benign, p=0.036).

Although there are overlapping MRI characteristics between benign and malignant TSGCTs, malignant TSGCTs are more likely to exhibit larger size, extra-articular location, irregular margins and prominent perilesional vessels compared to their benign counterparts. Some malignant TSGCTs may not be associated with a synovial-lined structure on imaging.