PMC8714914_01
Cervical spinal cord, cat. (A) Transversal section of formalin-fixed spinal cord with leptomeningeal pale, gray-beige mass (dashed line: junction tumor-spinal medulla). (B) Diffuse, basophilic cell infiltrates and edema within leptomeninges with compression of spinal cord. Spinal nerves (asterisks) are omitted by the tumor. HE stain. (C) Neoplastic infiltrates with junction to spinal medulla (bottom right) and necrosis (asterisk), HE stain. Scale bar: 50 mum. (D) High mitotic activity within the neoplasm (arrows), HE stain. Scale bar: 20 mum.
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F1
A radiological examination of the thorax, abdomen and the proximal hind limbs showed a mildly increased interstitial pattern in the craniodorsal lung, but no abnormalities in the skeleton or the spinal cord (Supplementary Figure 1A). CSF was excluded via PCR. Computed tomography (CT) of the entire body was performed but showed no abnormalities of the central nervous system (Supplementary Figures 1B,C). After formalin fixation, cross sections revealed a well demarcated, gray-beige, soft, subdural thickening within the whole circumference of the spinal cord, involving primarily the cervical part, and the medulla oblongata with partial compression of the neuroparenchyma (Figure 1A). Histopathological examination of representative localizations of the CNS (cerebral cortex, hippocampus, cerebellum, mesencephalon, medulla oblongata, and cervical, thoracic, lumbar, and sacral spinal cord) revealed a restriction of the mass to the subarachnoidal space (Figure 1B). Multifocally, large necrotic areas were present (Figure 1C). There was mild anisocytosis and -karyosis with a mitotic count of 20 mitoses per 2.37 mm2 (Figure 1D).
Spinal cord, cat. Tumor cells are diffusely immunopositive for OLIG2 (A), doublecortin (B), and MAP2 (C). The majority of tumor cells stained positive with synaptophysin (D). Positive vimentin reaction is mainly restricted to tumor:associated vasculature (E). High proliferation activity was demonstrated with positive nuclear staining for Ki-67 (F). Scale bars: 50 mum.
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F2
Neoplastic cells showed a diffuse, intranuclear expression of oligodendrocyte transcription factor 2 (OLIG2) and doublecortin (Figures 2A,B). Moreover, tumor cells exhibited a diffuse cytoplasmic expression of microtubule-associated protein 2 (MAP2) and synaptophysin (Figures 2C,D). Some of the neoplastic cells showed a cytoplasmic vimentin expression (Figure 2E). Ki-67 as a proliferation marker protein was detected in more than 50% of the neoplastic cells (Figure 2F).