PMC8769407_01
CT and MRI images for screening test. (A) Contrasted CT showed multiple hypodensity lesions without contrast enhanced area. (B) FLAIR images demonstrating multiple hyperintensity lesions including right cerebellar and cerebral hemispheres. (C) Diffusion-weighted images demonstrated multiple hypointense lesions. (D) Gd-enhanced MRI images showed multiple ring-like enhanced lesions, and some lesions revealed open-ring sign (arrow). CT: computed tomography, FLAIR: fluid-attenuated inversion recovery, MRI: magnetic resonance imaging.
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F1
A head CT revealed multiple low-density lesions including right frontal, temporal and occipital lobes, and right cerebellar hemisphere and no contrast-enhanced lesions were detected (Fig. 1A). On brain magnetic resonance imaging (MRI), these lesions were hyperintense on T2-weighted imaging, fluid-attenuated inversion recovery and diffusion-weighted images (Figs. 1B and 1C). Most lesions demonstrated ring-like enhancement (Fig. 1D) and some parts showed open-ring enhancement (Fig. 1D, arrow) with gadolinium.
(A) Biopsy; surface of right frontal lobe after removal of arachnoid membrane. A grayish white and jelly-like soft tumor tissue was detected on cortical surface macroscopically. (B) Hematoxylin and eosin staining of a biopsy specimen from lesion of right frontal lobe showing small round cell tumor cells around the vessels. Immunohistochemical staining for CD3 (C), CD4 (D), CD5 (E), CD8 (F), CD45 (G) as T-cell markers were positive, and CD20 (H) CD79a (I) as B-cell markers, CD10 (J), CD30 (K), CD56 (L) as other markers were negative. (M) In situ hybridization for EBV encoded RNA was negative. EBV: Epstein-Barr virus.
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F2
A brain biopsy examination for a lesion of right frontal lobe was performed (Fig. 2A). Pathological examination showed a small round cell tumor around the vessels on hematoxylin and eosin staining (Fig. 2B), and immunohistochemical staining revealed that tumor cells were positive for CD3, CD4, CD5, CD8 and CD45(LCA) as T-cell markers (Fig. 2C-2G), and were negative for CD10, CD79a as B-cell markers (Fig. 2H and 2I), CD20, CD30, and CD56 as other markers (Fig. 2J-2L). RNA (EBER) was negative (Fig. 2M). Results of additional laboratory analyses after the pathological examination were as follows: soluble interleukin-2 receptor 566 U/mL, serum immunoglobulin G (IgG) to EBV virus capsid antigen (VCA) 320, serum IgM to EBV VCA <10, serum EBV-nuclear antigen (EBNA) 40.
Follow-up MRI (FLAIR): (A) 1 month, (B) 3 months, and (C) 9 months after MTX withdrawal. FLAIR: fluid-attenuated inversion recovery, MRI: magnetic resonance imaging, MTX: methotrexate.
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F3
The tumor regressed and the symptoms were resolved soon after MTX withdrawal (Fig. 3A). The patient started to take iguratimod again to control RA symptoms, and it did not affect tumor control. Cessation of iguratimod was 7 weeks. Complete remission has been obtained more than 9 months on MRI (Figs. 3B and 3C), and no recurrence of neurological symptom has occurred more than 20 months.