case_images: PMC8572034_01
case_images: Preoperative computed tomography (CT) findings. Initial CT image on admission showing tumor in the sphenoid sinus (a) and destructive changes in the left petroclival synchondrosis (arrow) (b).
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case_images: PMC8572034_01_SNI-12-500-g001.jpg
case_images: F1
case_images: Computed tomography (CT) revealed enlargement of the left petroclival synchondrosis with osteoclastic changes and a soft-tissue mass within the adjacent sphenoid sinus [Figure 1].
case_images: Preoperative magnetic resonance imaging findings. Contrast-enhanced T1-weighted image showed the sphenoid sinus lesion with homogenous enhancement (*) (a). The tumor involved several skull base structures and extend into posterior fossa (b).
case_images: SNI-12-500-g002.jpg
case_images: PMC8572034_01_SNI-12-500-g002.jpg
case_images: F2
case_images: Magnetic resonance imaging (MRI) revealed a heterogeneously enhanced en plaque lesion involving the left jugular foramen and hypoglossal canal, extending into the left sigmoid sinus [Figure 2a and b].
case_images: Intraoperative findings. The tumor exposed by the transsphenoidal approach underlying the edematous sphenoid sinus mucosa (a). The tumor was relatively fibrous and was resected using ultrasound aspirator (b). Residual tumor connected to the petroclival lesion through the destructive clivus (allows) (c).
case_images: SNI-12-500-g003.jpg
case_images: PMC8572034_01_SNI-12-500-g003.jpg
case_images: F3
case_images: Intraoperatively, the tumor was found to extend into the sphenoid sinus and underlie the edematous mucosa of the sinus [Figure 3a]. The tumor was soft and relatively hypovascular, and was resected in sections [Figure 3b]. The majority of the tumor was smoothly detached from the adjacent mucosa; however, it was partially adherent to the clival region, which was presumed to be a consecutive lesion with a petroclival component [Figure 3c].
case_images: Hematoxylin-eosin staining of tumor cells and immune histochemical staining of CD99. HE staining showed proliferation of atypical round cells with hyperchromatic nuclei, containing some myotonic figures (a). Immunohistochemical staining showing CD99 expressions in the cell membrane (b).
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case_images: PMC8572034_01_SNI-12-500-g004.jpg
case_images: F4
case_images: Histopathological examination revealed a lesion composed of round cells with clear cytoplasm and uniformly round nuclei [Figure 4a]. The tumor cells were immunohistochemically positive for CD99 [Figure 4b].
case_images: Postoperative magnetic resonance imaging findings (22 months after). Contrast-enhanced T1-weighted image showing that thickening of the sinus mucosa due to sinusitis, however, elimination of the petroclival tumor that had extended into the surrounding structures.
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case_images: PMC8572034_01_SNI-12-500-g005.jpg
case_images: F5
case_images: At the 22-month post-surgical follow-up, the patient had recovered well with no clinical or radiological evidence of recurrence or metastatic disease [Figure 5].