Background: Primary soft tissue giant cell tumor (GCT-ST) is a rare tumor with low malignant potential . Here we reported two cases of patients with soft tissue giant cell tumor in the limb, including their clinical and imaging findings (conventional Magnetic resonance imaging (MRI) and Diffusion-weighted imaging (DWI)). Methods: This retrospective study included two pathology-confirmed GCT-ST patients. Plain MRI, dynamic contrast enhancement MRI (DCE-MRI), and DWI were performed with a 3.0T whole-body MR scanner before surgery. The following characteristics of lesion were recorded: signal intensity on T 1 FSPGR and T 2 WI, morphology, maximum lesion size, time-intensity curve (TIC) on DCE-MRI, and apparent diffusion coefficient (ADC) value from DWI. Results: The maximum lesion size ranged from 4.0 cm to 6.0 cm. Signal intensities of all lesions were heterogeneous on T 1 FSPGR and T 2 WI. Nodular enhancements were observed for all lesions with either oval or irregular shapes on MRI. All lesion margins were blurred, and internal enhancements were heterogeneous on DCE-MRI. TIC appeared with a slow increase in type. Lesions on DWI (b=500s/mm 2 ) were hyperintense with a higher mean ADC value of 2.19×10 −3 mm 2 /s compared to surrounding normal soft tissue (1.03×10 −3 mm 2 /s). Conclusions: MRI features of these two GCT-STs include heterogeneous signal intensity within the lesion on T 2 WI and T 1 FSPGR, nodular enhancement with blurred margins, either oval or irregular shapes, and a slow increase enhancement of TIC on DCE-MRI. DWI may be a useful tool for differentiating benign soft tissue mass from giant cell-rich soft tissue neoplasms or malignant tumors. However, these findings need to be confirmed using a higher sample study.

Background Primary soft tissue giant cell tumor (GCT-ST) is a rare tumor with low malignant potential. Here we reported two cases of patients with soft tissue giant cell tumor in the limb, including their clinical and imaging findings (conventional Magnetic resonance imaging (MRI) and Diffusion weighted imaging (DWI)).Methods This retrospective study included two pathology-confirmed GCT-ST patients. Plain MRI, dynamic contrast enhancement MRI (DCE-MRI), and DWI were performed with a 3.0T whole-body MR scanner before surgery. The following characteristics of lesion were recorded: signal intensity on T 1 FSPGR and T 2 WI, morphology, maximum lesion size, time intensity curve (TIC) on DCE-MRI, and apparent diffusion coefficient (ADC) value from DWI.Results The maximum lesion size ranged from 4.0 cm to 6.0 cm. Signal intensities of all lesions were heterogeneous on T 1 FSPGR and T 2 WI. Nodular enhancements were observed for all lesions with either oval or irregular shapes on MRI. All lesion margins were blurred, and internal enhancements were heterogeneous on DCE-MRI. TIC appeared with a slow increase type. Lesions on DWI (b=500s/mm 2 ) were hyperintense with an higher mean ADC value of 2.19×10 −3 mm 2 /s compared to surrounding normal soft tissue (1.03×10 −3 mm 2 /s).Conclusions DWI may be a useful tool for differentiating benign soft tissue mass from giant cell-rich soft tissue neoplasms or malignant tumors.