Hemorrhagic Tumefactive NMOSD Mimicking Glioma: AQP4-IgG-mediated Cortical Vascular Vulnerability
Shilin Yang1, Wei Yan2, Siyuan Song3
1Department of Neurology, Huashan Hospital, Fudan University, 2Department of Neurology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, 3Baylor College of Medicine
Objective:
To describe a rare case of hemorrhagic tumefactive neuromyelitis optica spectrum disorder (NMOSD) mimicking glioma and to illustrate the potential mechanism of aquaporin-4 immunoglobulin G (AQP4-IgG)–mediated cortical vascular vulnerability.
Background:
Although tumefactive demyelinating lesions can occur in a small subset of patients with NMOSD, concomitant intracerebral hemorrhage is exceedingly rare.
Design/Methods:
Case report
Results:

A 28-year-old woman presented with a 1-month history of headache and difficulty finding words. Neurological examination revealed mild expressive aphasia. Brain MRI revealed a left frontotemporal mass-like lesion with heterogeneous signals, marked edema, and intralesional hemorrhage causing midline shift. Magnetic resonance spectroscopy showed decreased N-acetylaspartate and elevated choline (Cho/NAA > 2.0), suggesting glioma. Positron emission tomography–computed tomography (PET-CT) demonstrated mild fluorodeoxyglucose (FDG) uptake. During the preparation for surgery, her headache and speech problem improved spontaneously, and follow-up MRI two weeks after the initial MRI showed partial hemorrhage resorption with appearance of a new small right temporal lesion. Susceptibility-weighted imaging confirmed multifocal microhemorrhage within both lesions. In view of the partial spontaneous improvement of symptoms and the initial radiological finding, alternative etiologies other than glioma were explored. Serum AQP4-IgG was positive (titer 1:32, cell-based assay). No spinal cord or optic nerve involvement was observed on MRI. The patient was diagnosed with NMOSD based on the 2015 criteria.

The patient was treated with intravenous methylprednisolone at 240 mg/day for 5 days with tapering, followed by oral mycophenolate mofetil at 500 mg twice daily. Her headache resolved completely, and MRI three weeks after treatment showed substantial regression of the lesions and surrounding edema. Over two years of follow-up, she remained relapse-free with full radiological resolution.

Conclusions:

Hemorrhagic tumefactive NMOSD represents a reversible astrocytopathic phenotype caused by AQP4-IgG–induced cortical microvascular fragility. The coexistence of a hemorrhagic mass lesion and mild or spontaneously resolving symptoms should prompt AQP4-IgG testing to avoid unnecessary biopsy or surgery.

10.1212/WNL.0000000000215360
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