To study MRI and clinical manifestation of posterior cranial fossa tumors in children, in order to improve the recognition of clinical and decrease the misdiagnosis rates on posterior cranial fossa tumors in children.

From February 2014 to April 2015, a total of 8 cases of children with posterior cranial fossa tumors in West China Second University Hospital, Sichuan University who diagnosed by postoperative pathological examination were enrolled in the study. MRI examination method to posterior cranial fossa tumors in children: craniocerebral scanning was performed by 1.5T MRI in all 8 cases of patients. MRI conventional scanning included T1WI, T2WI, T2W-flair and sagittal T1WI. Gadolinium (Gd) contrast enhanced T1WI was performed in 4 cases. MRI and clinical characteristics were retrospectively analyzed. The value of MRI in diagnosis and treatment of children with posterior cranial fossa tumors were evaluated. The causes of clinical misdiagnosis of were analyzed. The study protocol was approved by the Ethical Review Board of Investigation in Human Being of West China Second University Hospital, Sichuan University.

According to the criteria of pathological classifications of posterior cranial fossa tumors, 8 cases of posterior cranial fossa tumors were divided into medulloblastoma (2 cases), cerebellar hair cell astrocytoma (1 case), brain stem encephalitis (3 cases), ependymoma (1 case) and anaplastic ependymoma (1 case). The clinical manifestations of the 8 patients were non-specific, which were dyskinesia, headache, vomiting, cough and etc.. The common MRI features were tumors in the posterio cranial fossa which involved in brain stem, fourth ventricle and cerebellum. The specific clinical manifestations and MRI features of different pathological classifications of posterior cranial fossa tumors were as follows. ①Medulloblastoma (2 cases) was with dyskinesia, facial paralysis, and solid masses in the vermis cerebelli. ②Cerebellar hair cell astrocytoma (1 case) was with dyskinesia, gait abnormal, and obvious enhancement nodule in the cerebellar. ③Brain stem encephalitis (3 case) was with instability of gait, dysdipsia, dysphonia, and masses in the brain stem enhanced lightly. ④Ependymoma (2 case) was without specific clinical features and with tumor in the forth ventricle grew through the lateral aperture and with metastasis by cerebrospinal fluid. Among 8 cases, 3 cases were clinically misdiagnosed, 2 cases were brain stem encephalitis and 1 case was anaplastic ependymomas. The reasons of clinical misdiagnosis were the nonspecific signs and symptoms, and the delayed cranial MRI examination.

There were some significant MRI features in posterior fossa tumors in children. Early application of MRI and acquaintance with the clinical manifestations can reduce the clinical misdiagnosis rate. MRI is of great significance in diagnosis and differential diagnosis of posterior cranial fossa tumors in children.