PMC10184201_01
PMC10184201_02
Non-injected cerebral CT showing an iso to hyper dense, extra-axial left frontal and right parieto-occipital processes.
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Tomography (CT) revealed bifocal hyperdense and compressive extra-axial masses with perilesional edema in the right parieto-occipital region and the left frontal region. These masses produce a mass effect on the lateral ventricles and the middle line (Figure 1).
(a) Axial FLAIR magnetic resonance imaging showing expansive bifocal lesions, isointense on FLAIR with mass effect and vasogenic type edema (arrow); (b) Iso intense signal on T2; (c) Axial gadolinium-enhanced image; and (d) Axial sequence diffusion in b1000 revealing no restriction of diffusion.
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Gadolinium-injection demonstrated a strong and homogeneous enhancement (Figure 2).
(a) Macroscopic appearance of the mass; (b) Histologically, the lesion is constituted of large histiocytes having an eosinophilic and foamy cytoplasm (Hematoxylin-Eosin x20); (c) Many images of emperipolesis have been observed (arrow, Hematoxylin-Eosin x40); and (d) Note an inflammatory infiltrate rich in plasma-cells (Hematoxylin-Eosin x40).
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Macroscopically, the lesion was firm; greyish-white and lobulated (Figure 3a). Many images of emperipolesis were observed, that were highly suggestive of a Rosai-Dorfman disease (Figure 3).
At immunohistochemistry, histiocytes express S-100 protein (a) and CD163 (b).
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Immunostaining for BRAFV600E was negative (Figure 4).