[Neuronal intranuclear inclusion disease: a clinicopathological study of two cases]

Objective: To investigate the clinical manifestations, imaging features, histopathologic, immunohistochemical (IHC) and ultrastructure features of neuronal intranuclear inclusion disease (NIID). Methods: HE, IHC staining and EM were performed in cases of NIID diagnosed at the Department of Pathology, Jinling Hospital from 2018 to 2019. Results: Two cases were identified, including one male and one female; both patients were 76 years old. They were hospitalized because of nervous system dysfunction. MRI showed abnormal high signal intensity in corticomedullary junction of bilateral frontal lobes (male patient) and bilateral cerebral hemispheres (female patient). Light eosinophilic transparent inclusion bodies were seen in the nuclei of neurons in both rectal mucosa and cutaneous sweat glands, and these were positive for p62 by IHC. By scanning EM, the inclusion bodies in the sweat gland cells nuclei were round membranous structures consisting of 8-18 nm microfilaments. Conclusions: NIID is a rare, multi-system and slowly progressive neurodegenerative disease. Its clinical manifestations are highly diverse and easily misdiagnosed or missed. Neuroimaging can make a preliminary diagnosis. In the past, NIID can only be diagnosed through autopsy, and this study demonstrates that NIID can be confirmed through skin or rectal mucosal biopsy.