case_images: PMC10794010_01
case_images: PMC10794010_02
case_images: Initial Brain MRI at one year of age. The axial (A) and sagittal (B) contrast-enhanced T1-weighted images depict lesions arising from the ventricular lining (yellow arrows), causing noncommunicating hydrocephalus due to the obstruction of the aqueduct of Sylvius. In addition, two additional axial images (C and D), also contrast-enhanced T1-weighted, reveal multiple enhancing brain parenchymal lesions within the supratentorial and infratentorial compartments (indicated by blue arrows).
case_images: cureus-0016-00000052453-i01.jpg
case_images: PMC10794010_02_cureus-0016-00000052453-i01.jpg
case_images: FIG1
case_images: MRI, performed at the age of one year, revealed at least three enhancing lesions with restricted diffusion arising from the ventricular lining, measuring up to 26x28 mm, causing noncommunicating hydrocephalus. Multiple additional intra-axial enhancing lesions, measuring up to 18 mm, were observed in the cerebral hemispheres, cerebellar hemispheres, and brainstem (Figure 1).
case_images: Whole body PET scan shows no evidence of extracranial disease
case_images: cureus-0016-00000052453-i02.jpg
case_images: PMC10794010_02_cureus-0016-00000052453-i02.jpg
case_images: FIG2
case_images: Subsequently, a positron emission tomography (PET) scan was performed, which yielded negative results for extracranial disease, confirming the isolation of the disease to the CNS (Figure 2).
case_images: RDD in brain lesion biopsy. (A) Hematoxylin and eosin (H&E) stain, 100X magnification, showing sheets of monotonous histiocytes with a moderate amount of dense cytoplasm with intaking individual small lymphocytes with peripheral halos (navy arrows). (B) and (C), both 200X magnifications, histiocytes are highlighted by immunohistochemistry for CD 68 and CD163, respectively. (D) 200X magnification, CD1a is negative and it is seen only in a few cells (yellow arrows).. RDD - Rosai-Dorfman disease
case_images: cureus-0016-00000052453-i03.jpg
case_images: PMC10794010_02_cureus-0016-00000052453-i03.jpg
case_images: FIG3
case_images: Scattered histiocytes were identified, each containing a single intact lymphocyte with a peripheral halo in the cytoplasm (emperipolesis, Figure 3A). The immunohistochemistry (IHC) panel showed positive results for CD68, CD163, vimentin, integrase Interactor 1 (INI-1), CD1a in a few cells, and Ki67 in 10% of histiocytes, while being negative for oligodendrocyte transcription factor 2 (Olig2), CD56, cytokeratin, myeloperoxidase (MPO), and CD34 (Figures 3B, C, and D).