case_images: PMC10900506_01
case_images: MRI in December 2021. (A-E) The nodule in the pre-pontine cistern showed a low-intensity signal on T1-weighted imaging, a high-intensity signal on T2-weighted imaging, a high-intensity signal on diffusion-weighted imaging (DWI), a low-intensity signal on an apparent diffusion coefficient plot (ADC), and no enhancement on contrast-enhanced T1-weighted imaging; (F-I) the lesion is adjacent to the right edge of the pons and shows patch-like enhancement, the boundary is not clear; (C,J-L) the lesion extends from the optic chiasm to the beginning of the right abducens nerve, the lesion is in close proximity to the right trigeminal nerve, abducens nerve, and optic chiasm nerve.
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case_images: fig1
case_images: On December 28, 2021, a cranial MRI scan revealed a nodular abnormal signal in the pre-pontine cistern with unclear borders and irregular morphology, which was consistent with the imaging findings of epidermoid cysts (Figures 1A-E). However, a patchy enhancement lesion was shown in the adjacent pons, and the clinician thought that this feature might due to inflammation in the pons adjacent to the epidermoid cyst and could not rule out the possibility of a tumor (Figures 1F-I). The lesion extends from the optic chiasm to the beginning of the right abducens nerve, the lesion is in close proximity to the right trigeminal nerve, abducens nerve, and optic chiasm nerve (Figures 1C,J-L).
case_images: Imaging taken in July 2022. (A) Cystic lesions are visible on the right side of the pons on T1-weighted imaging; (B-D) contrast-enhanced scan image showing that the lesion had a ring shape and nodular enhancement features, and the lesion invaded the brachium pontis and was considered to be a neoplastic lesion.
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case_images: fig2
case_images: On July 6, 2022, the patient underwent another MRI scan, which showed that the right pontine edge enhancement lesion was larger than it was on December 28, 2021, and that cystic lesions had appeared (Figure 2).
case_images: Imaging examination in October 2022. (A-D) A cystic solid shadow was observed in the right pons, brachium pontis, and right cerebellar hemisphere; (E) the adjacent meninges were slightly thickened; (F) speckled calcification appeared in the low-density lesion area; and (G) single-voxel 1H + MR spectroscopy (MRS).
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case_images: The results showed that the lesion was further expanded than it was on July 6, 2022 (Figures 3A-D). The lesions were in close proximity to the right abducens nerve, some lesions invaded the brainstem, and the meninges adjacent to the brainstem were thickened (Figure 3E). CT of the brain showed an area of low-density lesions with speckled calcifications (Figure 3F). The area of the lesion located in the pontine and right brachium pontis showed an elevated Cho peak, a decreased NAA peak, and a Lac peak (Figure 3G).
case_images: Histopathology. (A) Histopathology taken from the anterior pre-pontine cistern shows lamellar keratoses with a stratified squamous epithelium lined with a sac wall, consistent with the characteristics of an epidermoid cyst (HE x 100). (B) Histopathology taken from within the brainstem shows carcinoma invasion (HE x 100). (C-F) IHC results were taken from brainstem lesions: CK (AE1/AE3) was positive (C), GATA3 (D) was positive, Vimentin was focal-expressing (E), and Ki-67 proliferation index was 20%.
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case_images: fig4
case_images: Histopathological examination of tissue taken from the anterior pre-pontine cistern showed features consistent with epidermoid cysts (Figure 4A). Histopathological results of tissue taken from the brainstem showed invasion by carcinoma (Figure 4B); immunohistochemistry (IHC) confirmed that CK (AE1/AE3) was positive (Figure 4C), GATA3 (Figure 4D) was positive, vimentin was focally expressed (Figure 4E), GFAP, S-100, IDH-1, Oligo-2, TTF-1, PAX8, CK20, and CDX-2 were negative, and the Ki-67 proliferation index was 20% (Figure 4F).
case_images: MRI-enhanced image of postoperative lesions. (A) The image of some unresected lesions in the brainstem area before postoperative radiotherapy; (B) unresected cystic solid lesions in the brainstem on January 6, 2023; (C) the image of brainstem lesions on February 25, 2023; (D) diffuse meningeal metastases on February 25, 2023; (E) diffuse meningeal metastases on July 6, 2023; and (F) diffuse meningeal metastases on October 06, 2023.
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case_images: October 18, 2022, the patient underwent the first cranial MRI enhancement examination (Figure 5A) after surgery, and the patient underwent radiation therapy in another hospital for 1 month. On January 6, 2023 (Figure 5B), magnetic resonance enhancement revealed that the unresected cystic solid lesions in the brainstem were slightly smaller than on October 18, 2022. On February 25, 2023, the lesions (Figure 5C) were slightly larger than before, with diffuse meningeal metastases (Figure 5D). During this period, on July 6, 2023 (Figure 5E), MRI showed that the condition of cranial metastases has improved compared to before. On October 06, 2023, the cranial metastases (Figure 5F) progressed than it was on July 6, 2023, and chemotherapy was performed with temozolomide.