demyelinating pseudotumor
A large demyelinating lesion that mimics a neoplasm clinically and radiologically.
Full Definition
Demyelinating pseudotumor, also known as tumefactive demyelination, refers to large demyelinating lesions that clinically and radiologically simulate brain tumors. These lesions are typically greater than 2 cm in diameter and show mass effect, edema, and sometimes ring enhancement on neuroimaging. Histologically, they demonstrate active demyelination with relative axonal preservation, macrophage infiltration, and reactive gliosis. The lesions may be part of multiple sclerosis, acute disseminated encephalomyelitis, or other inflammatory demyelinating conditions. Biopsy may be necessary for diagnosis when imaging cannot distinguish the lesion from a neoplasm, and corticosteroid therapy often results in dramatic improvement.
Usage
Usage note: Emphasize mimicry of neoplasm; note steroid responsiveness.
In Context
- "The large enhancing lesion proved to be demyelinating pseudotumor rather than glioblastoma." — Stereotactic biopsy report
- "Demyelinating pseudotumor showed dramatic response to corticosteroid therapy." — Clinical follow-up note