Clinical and image analysis of extrarenal non-central nervous system malignant rhabdoid tumors

Abstract

Objective To demonstrate the clinical and imaging features of extrarenal malignant rhabdoid tumor(MRT) outside the central nervous system(CNS) in children and to raise awareness of the disease. Methods A retrospective database review was made of 15 patients diagnosed with extrarenal MRT outside the CNS in Beijing Children′s Hospital, Capital Medical University from April 2008 to February 2017.The ultrasound, CT and magnetic resonance imaging(MRI) examinations were performed in 12, 10 and 7 cases, respectively, and the clinical and imaging features were analyzed. Results The 15 patients included 8 boys and 7 girls.The age at presentation varied from 11 days to 12 years and 9 months old with a median age of 4 years old.The primary tumors were predominant solid masses, most of which were irregular, with a length of 2.20-11.70 cm [(5.87±2.57) cm]. The primary tumors had variable locations, relatively tended to occur in the head and neck region (6 cases) and the mediastinum (4 cases). On ultrasound, 11 cases of the tumors were heterogeneous, 7 cases of the tumors were accompanied with cystic change, and the solid part was mainly hypoechoic.On CT, density of 6 cases of the tumors was uneven, 3 cases presented cystic change, 4 cases were with calcification, and the solid part had slightly low density, with enhancement of different degrees.On MRI, 7 cases of tumors showed mixed signal, 5 cases with cystic change of different degrees; the solid part mainly showed isointensity or slightly hypointensity on T1 weighted image and hyperintensity or slightly hyperintensity on T2 weighted image, with restricted diffusion and predominantly heterogeneous enhancement.Medical imaging showed definite hemo-rrhage within tumors in 5 patients, and metastases occurred in 6 patients at the time of diagnosis, the adjacent bone destruction occurred in 3 patients, and the tumor tissue of 3 patients extended into the spinal canal. Conclusion Extrarenal MRT outside the CNS is more common in preschool kids, most of which are large and heterogeneous solid masses, often with cystic change, sometimes with hemorrhage and calcification; the solid part with restricted diffusion and inhomogeneous enhancement.Some of the patients had metastasis and local invasion. Key words: Malignant rhabdoid tumor; Computed tomography; Magnetic resonance imaging; Child