PMC8081911_01
(A-D) MR-Images of the brain and spine showing multiple periventricular, parenchymal and leptomeningeal contrast enhancements at the time of diagnosis. T1-weighted contrast-enhancement MRI sequence of the brain (A-C) and T2- weighted MRI sequence of the spine (D). Arrow pointing to the site of biopsy (C). (E-H) MR-Images 6 weeks after high-dose steroid treatment showing near complete remission. T1-weighted contrast-enhancement MRI sequence of the brain after steroid treatment (E-G) and T2- weighted MRI sequence of the spine after steroid treatment (H). (I-L) Histology of the stereotactic biopsy. Demyelinated areas are shown in Kluver-Barrera staining (I) and CNP-ase staining (J), with numerous foamy macrophages [CD68, (K)]. Scattered CD45+ lymphocytes are present in the demyelinated areas (L).
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MRI conducted at that time showed multiple spot-shaped periventricular, leptomeningeal and parenchymal contrast enhancements suggestive of parenchymal and predominantly leptomeningeal metastasis ( Figures 1A-C ). MRI of the spine was consistent with leptomeningeal metastasis with nodular enhancement tracking along the cervical and thoracic segments and conus terminalis ( Figure 1D ). Since the MRI was strongly indicative of leptomeningeal metastasis whereas CSF was negative for tumor cells, the patient was subjected to stereotactic biopsy of a right-sided contrast-enhancing periventricular lesion ( Figure 1C ). The neuropathologic evaluation showed white matter tissue with reactive gliosis and sharply demarcated demyelinated areas (Kluver-Barrera staining ( Figure1I ), positive staining for myelin protein CNPase ( Figure 1J ) and MBP, as well as dense macrophagocytic infiltrates ( Figure 1K ) and perivascular accentuated lymphocytic CD45+ ( Figure 1L ) infiltrates containing CD3+ and CD20+ cells of low to moderate density. MRI were induced by ICI treatment, high-dose corticosteroid treatment was initiated (1g/d for five days) with consequent steroid tapering and prompt clinical improvement was observed. MRI and CSF re-evaluation were conducted six weeks later showing a near-complete remission ( Figures 1E-H ,  Table 1 , right column).