[Analysis of pathological characteristics of acute and chronic cerebral tumefactive demyelinating lesions].

OBJECTIVE: To summarize the clinical features, neuroimaging findings and pathological characteristics of pathologically confirmed tumefactive demyelinating lesions (TDL). METHODS: The clinical features, neuroimaging findings and pathological characteristics were retrospectively collected and analyzed for 58 patients with pathologically confirmed TDLs.For pathological studies, a combination of hematoxylin and eosin staining, myelin staining (Luxol fast blue/periodic acid-Schiff or immunohistochemistry for myelin basic protein), macrophage-specific marker (immunohistochemistry for KiM1P or CD68) and staining for axons (Bielschowski silver impregnation or immunohistochemistry for neurofilament protein) were employed. RESULTS: The mean age of onset was 6-56 (36 ± 13) years. The onsets were acute (n = 21, 36%), subacute (n = 27, 46.5%) and chronic (n = 10, 17.5%). The diagnoses of TDL were confirmed by repeat biopsy and pathological examinations (n = 2, 3.4%).In acute phase, the plaques of lesions were characterized by massive demyelination with relatively axonal preservation associated with prominent reactive astrocytosis and profound infiltrates of macrophages.In plaques of chronic lesions, demyelinated lesions with relative axonal preservation and sharply defined margins were major findings. And myelin-laden macrophages accumulated at the edges of plaques and stayed relatively inactive with densely gliotic center and processbearing astrocytosis. CONCLUSION: TDL is a distinct entity of demyelinating disease.Even though it is often misdiagnosed as neoplasm in brain, bilateral brain involvements and multiple lesions are more common in TDL. The pathological features of TDL are important for the early diagnosis of this disease and helpful for differentiating with brain tumors and central nervous system vasculitis.