PMC5563365_01
Ptosis of the right eye and fixed and dilated right pupil.
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F1
MRI brain with contrast showing Merkel cell carcinoma (MCC) metastasis to the clivus and invasion into the cavernous sinus. (A) Transverse view. Arrow is pointing to the mass in the clivus. (B) Sagittal view. Arrow is pointing to the mass in the clivus. (C) Coronal view. (D) Magnified view of the cavernous sinus from (C). There is invasion of the metastatic MCC into the cavernous sinus with likely impingement on the cranial nerves.
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F2
Brain MRI showed infiltrative, peripherally enhancing tumor centered within the clivus with soft tissue extension into the cavernous sinus (Figure 2). The left V3 nerve can be secondary to the clival mass or to extension of the cavernous sinus tumor infiltration since V3 is located adjacent to both structures (Figure 2D).
Histological and immunophenotypical features of the clival mass. (A) H&E stain at 20x showing small round blue cells. (B) CD56 stain positive. (C) Cytokeratin CAM 5.2 stain positive. (D) Magnified view of the cytokeratin CAM 5.2 stain showing perinuclear dot-like pattern.
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F3
TTF-1, leukocyte common antigen (LCA), S-100, and melan-A (Figure 3). These findings were consistent with metastatic MCC.
PMC5563365_02