OBJECTIVE: Intracranial inflammatory demyelinating pseudotumor is a specific subtype of multiple sclerosis, commonly found in the peri-lateral ventricles and occasionally in the spinal cord and optic nerve, and is easily misdiagnosed as glioma on imaging and pathology because it is characterized by the formation of limited masses and astrocytic proliferative nodules on the basis of demyelinating changes, and thus its clinical presentation, imaging and pathological features are summarized in this paper. METHODS: A total of 725 stereotactic brain tissue biopsies were retrospectively analyzed from November 2001 to December 2008, of which 32 rare inflammatory demyelinating pseudotumors were detected, accounting for 4.41% of the total number of biopsies, and their epidemiology, pathological manifestations, imaging features, diagnosis and treatment prognosis were discussed in the context of literature review. Results: The age of our patients ranged from 6 to 63 years old, with an average of 33.6 years old, 17 males and 15 females, with males concentrated in the age group of 30 to 48 years old (12/17), and the duration of the disease ranged from a few days to several years. There were 10 cases with a history of more than 2 years. There were 3 cases with a clear history of viral infection before consultation and 1 case with a history of vaccination. There were 14 cases (43.7%) of isolated single intracranial lesions and 18 cases (56.3%) of multiple lesions, most of which were located in the bilateral paraventricular white matter or brainstem, pontocerebellar arms, and some cases could involve the spinal cord. The clinical manifestations included headache, nausea, vomiting, visual field loss, confusion, slowness of speech, paralysis, positive pathological signs and other localized symptoms and signs of brain parenchymal damage and increased intracranial pressure, which may have transient remission and recurrence, with symptoms and signs similar to those of tumors. Most of them have nodular or ring-like enhancement, and the occupying effect and edema are not proportional to the size of the lesion; “open ring-like enhancement” is a typical feature, accounting for about 62% of the cases with ring-like enhancement. Biopsy pathology showed abundant cells in the lesion, mostly foamy phagocytes, lymphocytes and plasma cells. The lymphocytes were mainly found in the perivascular area and were distributed in a “cuff” pattern. Lymphocyte and macrophage infiltration was a distinctive feature of demyelinating pseudotumor; myelin staining showed heterogeneous staining, and the myelin sheath in the focal area was faded and lost, but the axon of the demyelinating area was preserved and its travel was not interrupted, and blue-stained myelin debris could be seen in the cytoplasm of macrophages; the treatment and prognosis of different pathological types were very different. Conclusion Intracranial inflammatory demyelinating pseudotumor is easily confused with intracranial tumor, with certain imaging features, more than multiple foci, and stereotactic brain tissue biopsy is the best option for definitive diagnosis.