Objective To investigate the clinical phenotype， imaging features， and skin pathological changes in patients with sporadic adult-onset neuronal intranuclear inclusion disease （NIID）.Methods A retrospective analysis was performed for the clinical data of seven patients with adult-onset NIID who attended Peking University People's Hospital from March 2018 to March 2021 and were diagnosed based on NOTCH2NLC genetic testing， including clinical， imaging， and skin pathological manifestations.Results The age of onset ranged from 33 to 73 years in these patients， with a mean of （54.43±15.47） years. Besides the core symptoms such as cognitive impairment and encephalopathy-like episode， the main clinical manifestations also included gastrointestinal symptoms such as nausea， vomiting， abdominal pain， and diarrhea in the early stage. Among the seven patients， five were found to have abnormal hyperintensity on diffusion-weighted imaging along the corticomedullary junction. All seven patients were found to have abnormal GGC repeat expansion in the untranslated region of the NOTCH2NLC gene， which ranged from 93 to 177 times. Skin biopsy revealed intranuclear inclusions in sudoriferous duct epithelial cells and fibroblasts. Immunohistochemical staining showed positive p62， and thin filamentous material without a membrane structure was observed under an electron microscope.Conclusions Sporadic adult-onset NIID has high clinical heterogeneity， and dermal pathology and genetic testing are necessary means to make a confirmed diagnosis.