PMC9309514_01
Imaging and magnetic resonance spectroscopy findings. (A) Body trunk computed tomography showed enlargement of the left testicle with heterogeneous content (arrow) and retroperitoneal lymph node (arrowhead). (B-D) Brain magnetic resonance imaging (MRI) on admission showed a high-intensity lesion in diffusion-weighted and fluid-attenuated inversion recovery (FLAIR) images, with iso-intensity in apparent diffusion coherence images. (E, F) The brain lesion enlarged afterward, but with no gadolinium enhancement. (G) Magnetic resonance spectroscopy showed high choline (Cho) peak, preserved N-acetyl aspartate (NAA) peak, and lactate (Lac) peak. Cr, creatine.
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F1
Whole-body CT showed enlargement of the left testicle and retroperitoneal lymph nodes (Figure 1A). Brain MRI revealed a T2 high-intensity lesion in the left internal capsule (Figures 1B-D) without gadolinium enhancement or a mass effect, which did not suggest brain metastasis. Gadolinium enhancement was still absent (Figures 1E,F). MR spectroscopy revealed an increased choline peak and an abnormal lactate peak, but the N-acetyl aspartate peak was preserved (Figure 1G).
Pathological findings of the brain biopsy. (A) Hematoxylin and eosin (HE) stains showed gliosis with widespread infiltration of inflammatory cells without neoplastic tissue. Perivascular inflammation was absent (arrowhead). (B) High-magnification HE showed diffuse foamy macrophage infiltration associated with reactive astrocytes (arrowheads). (C) CD68-immunostaining revealed clusters of macrophages. (D,E) Kluver-Barrera staining demonstrated myelin loss with myelin-laden macrophages (arrowheads). (F) Phosphorylated neurofilament immunostaining revealed axonal fragmentation and spheroids (arrowheads). The axonal loss was milder than myelin loss. Scale bars: (A) 100 mum. (B-E) 20 mum. (F) 10 mum.
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F2
The sampled specimen consisted of gliotic brain tissue with marked myelin loss and infiltration of inflammatory cells, including numerous macrophages, however, neither malignant tissue nor infarct lesion, was observed (Figure 2).
MRI findings before and after treatment. (A,B) Before treatment, brain magnetic resonance imaging showed a high-intensity lesion in the left basal ganglia (arrows). (C,D) After chemotherapy and immunotherapy, the brain lesion was reduced in size (arrows).
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F3
The hemiparesis and hemianopia remained, and he was referred to a rehabilitation hospital with MRI amelioration (Figures 3A-D).