MRI manifestations of primary intracranial malignant melanoma

CHEN Menglu; HE Haobo; LI Chun; QIU Qiande

doi:10.20258/j.cnki.1006-9011.2025.06.005

Abstract：Objective To explore the MRI features of primary intracranial malignant melanoma(PIMM)in order to improve the diagnostic accuracy of PIMM.Methods The MRI images and clinical data of 15 patients with PIMM confirmed by surgery and pathology were collected,and the MRI manifestations of PIMM patients were analyzed retrospectively,and the related litera-tures were reviewed.Results There were 3 multiple cases(7 lesions),among which two cases were located in frontal lobe and temporal lobe(4 lesions)and one case(3 lesions)was located in the frontal,temporal and occipital lobes.12 cases(12 lesions)were single,including 3 cases in frontal lobe,3 cases in parietal lobe,2 cases in occipital lobe,2 cases in temporal lobe,1 case in cerebellum,and 1 case in brain stem.The tumor size ranged from 1.8～5.3 cm,with an average of 3.2 cm.12 lesions were round or quasi-round,7 lesions presented with irregular shape.There were mild and moderate edemas in the tissues around the lesions,among which 12 lesions were adjacent to the surface of the brain and 7 lesions were located in the deep brain.Plain scan signal performance showed that seven lesions were melanotic type,the lesions showed high signal intensity on T1WI,low signal intensity on T2WI and high signal intensity on DWI.Two lesions were non-melanoma type,the lesions showed low signal intensity on T1WI and high signal intensity on T2WI and DWI.Five lesions were mixed type,the lesion signal showed mixed high and low signal on T1WI and T2WI,and high signal on DWI.Five lesions were hematoma type,the lesions showed mixed high and low signals on T1WI,high signals on T2WI and low signals on DWI.Enhanced MRI showed that after enhanced scanning,8 lesions were significantly enhanced and 11 lesions were moderately enhanced.Five lesions showed"meningeal tail sign".Conclusion Primary intracranial malignant melanoma is rare,with characteristic features such as high signal on T1WI,low signal on T2WI,and high signal on DWI.Atypical cases have diverse MRI manifestations,and diagnosis depends on pathology.