[MRI and CT diagnosis of rhabdomyosarcoma in the extremities:a report of nine cases].

ABSTRACT

BACKGROUND & OBJECTIVE: Imaging studies on rhabdomyosarcoma in the extremities have seldom been reported. This study was to explore the MRI and CT features of rhabdomyosarcoma in the extremities. METHODS: MRI and CT data of 9 patients with rhabdomyosarcoma in the extremities were analyzed. RESULTS: Among the 8 cases that received MRI examination, as compared with muscle, all tumors showed mixed low and intermediate signal intensity on T1WI, with the later being predominant; all tumors showed intermingling areas of hyper-, iso-, and/or hypo-signal intensity on T2WI; after Gd-DTPA injection, all tumors showed strong and heterogeneous enhancement. Five of them showed ill-defined margin and surrounding edema, the other 3 were well-circumscribed without conspicuous edema. Of the 3 cases that received CT examination, all tumors showed both low and intermediate density as compared with muscle on un-enhanced images, with the later being predominant; none of them showed calcification; 2 of them were ill-defined and the other 1 was well-circumscribed. The case that received contrast-enhanced CT examination showed strong and heterogeneous enhancement. Among all 9 cases, 8 showed necrosis or cystic changes, none showed hemorrhage and invasion of adjacent bone, but 3 showed adjacent blood vessel encasement and 1 showed tumor thrombosis in the adjacent vein. CONCLUSION: When MRI or CT reveals a soft tissue mass in the extremity with necrosis and strong and heterogeneous enhancement, especially when hemorrhage, calcification and adjacent bone invasion is not present,rhabdomyosarcoma should be considered.