Low-grade Myofibroblastic sarcoma: clinical and imaging findings

Low-grade myofibroblastic sarcoma (LGMS) is a rare type of tumor. Previous research has paid much attention to reporting pathological analyses of LGMS. However, only few systematic clinical and/or radiological studies have been conducted.

This study recruited 14 cases (8 males and 6 females) of LGMS. X-ray or computer tomography (CT) scan were performed on 11 cases. MRI was performed on 5 cases.

X-Ray and CT scan: Five cases developed LGMS in bones, including 3 cases in the distal femur, 1 in the right shoulder blade, and another 1 in the right inferior ramus. Massive infiltrative and vermiform bone destruction with poorly-circumscribed lesion margins and partial soft tissue masses were observed. The other 9 cases were developed in soft tissues. Out of them, 4 cases presented slightly irregular hyper- or lower-density masses with poorly-circumscribed margins. 2 cases presented massive calcification and ossification. Significant enhancement was observed in 1 case, while no obvious enhancement was seen in the other 2 cases. MRI: MR images of 5 cases revealed homogeneous iso- or hyper-signal intensity on T1WI and homogeneous or heterogeneous hyper-signal intensity on T2WI. Enhanced MRI revealed homogeneous enhancement in 2 cases and rim enhancement in 1 case.

Our findings show that LGMS is characterized by invasiveness, metastases and calcification. Different radiological tools should be employed to make an accurate diagnosis.