PMC2902057_01
CT. The tympanum and mastoid were filled with an isodensity shadow with bone erosion. The wall of the carotid artery and jugular bulb appeared to be thick and erosive. CA: carotid artery, JB: jugular bulb, TMJ: temporomandibular joint, EAC: external auditory canal, VII: the seventh nerve, PP: Petrous pyramid.
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fig1
The tympanum and mastoid were filled with an isodensity shadow indicating bone erosion, and the wall of the carotid artery canal and the jugular bulb appeared to be thick and erosive on CT (Figure 1).
Dynamic enhanced MRI. The mass close to the carotid artery and jugular bulb through the tympanum and mastoid was enhanced in the early phase of the dynamic MRI (white arrows).
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fig2
The enhanced mass also appeared on the underside of the promontory of the middle ear (Figure 2).
Pathological findings. The histopathological findings revealed a solid tubuloglandular pattern, resembling an adenomatous tumor of the middle ear ((a) examination on low power). One cell type, the A-type cells lining the glandular lumina, was observed with a lower frequency. These slender darkly staining cells had the appearance of endothelial cells. The other cells, the B-type cells, were observed in glandular structures and were characterized by a round or oval nucleus and an abundant, pale cytoplasm ((b) examination on high power). The B-type cells were typically positive for cytokeratin, chromogranin A, and synaptophysin, and 6.6% of the carcinoid tumor cells were positive for MIB-1 staining.
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The tumor cells had round, oval, or slightly irregular nuclei with finely-dispersed chromatin, and occasionally formed glandular or tubular structures (Figures 3(a) and 3(b)). The positive rate of MIB-1 was 6.6% (Figure 3).