case_images: PMC9679371_01
case_images: Plain X-ray film of the lateral view of the head. Radiolucent mass shadows in the occipital region (*) and opacification of the occipital bone (arrowhead) were observed.
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case_images: F1
case_images: Head radiographs showed a mass with increased internal permeability and bone obscuration in the occipital area (Figure 1); however, the thoracic radiographs were unremarkable.
case_images: Head MR images. Transverse T2 weighted (A), FLAIR (B), T1 weighted (C), and T1 weighted post-contrast (D) images at the level of posterior fossa, and sagittal T2 weighted (E) and T1 weighted post-contrast (F) at the level of the left cerebellum. A large mass lesion was found in the left occipital subcutaneous tissue, posterior fossa, and left cerebellar bridge angle region. The mass showed mixed hyper intensity was recognized extracranial region (*) and strong enhancement on the margins and near the meninges (arrow).
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case_images: F2
case_images: TR/TE = 8,292/78), and T1-weighted images (T1WI: spin-echo [SE], TR/TE = 400/15) with and without intravenous (IV) gadodiamide (0.2 mL/kg, OMNISCAN, GE Healthcare Pharma, Tokyo, Japan) in the transverse, sagittal, and dorsal planes. The MRI findings demonstrated a large oval space-occupying mass located from the subcutaneous tissue in the left occipital region to the posterior fossa and left cerebellar bridge angle region. The mass showed mixed hyperintensity on T2WI and FLAIR, mild hypointensity on T1WI, and strong enhancement on the margins and near the meninges on post-contrast T1WI (Figure 2).
case_images: Cranial CT images [(A) bone conditions, (B) soft tissue conditions]. Contrast-enhanced CT image of the head. Soft tissue mass formation was observed mainly in the left temporal-occipital region (*). Furthermore, the region showed destruction of the occipital bone (arrowhead) and an unclear boundary with the brain parenchyma. No obvious metastatic findings were found in the chest or abdomen. CT, computed tomography.
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case_images: F3
case_images: Tochigi, Japan) showed occipital bone destruction at the lesion site (Figure 3). Since no obvious abnormal findings were found on chest and abdominal CT, the head mass was considered the primary lesion. Tru-cut biopsy was then performed to identify the lesion.
case_images: Histopathology of the tumor lesions. A bundle-like growth of spindle-shaped mesenchymal tumor cells was observed between the myofibril and the collagen bundles. The tumor cells were moderately irregular in size and had eosinophilically stained cytoplasm. The tumor cells were highly atypical, and mitotic figures were rare. No intravascular invasion of the tumor in the search area was detected.
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case_images: F4
case_images: The cells were highly atypical and had rare mitotic figures, whereas no intravascular tumor invasion was observed within the search area (Figure 4).
case_images: Immunohistochemical staining of the tumor. The tumor cells were stained positively for S-100, glial fibrillary acidic proteins, Olig-2, and SOX10 (x 600).
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case_images: F5
case_images: Neoplastic cells were positive for S100, GFAP, Olig-2, and SOX10 (Figure 5).
case_images: Immunohistochemical staining of the tumor. The tumor cells were stained negatively for NF, E-cadherin, and Claudin-1 (x 600).
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case_images: F6
case_images: However, they were negative for NF, E-cadherin, and Claudin-1 (Figure 6).