PMC3108444_01
(a) The first manifestation of the tumor. The axial and coronal T1-weighted, contrast-enhanced MR scan shows a strongly enhanced lesion in the Meckel's cave. The large tumor is compressing the prepontine cistern, the pontocerebellar cistern and the pons. A clear border among the tumor, trigeminal nerve and the internal cerebral artery is indistinguishable. (b) Pre-operative axial T1-weighted MRI with contrast media revealing the first reoccurrence of the tumor in the left Meckel's cave. The volume of the tumor in the medial fossa is approximately 2.5 x 1.8 cm. Regressive changes and cystic compartment with liquid mirror image are visible within the lesion. Part of the tumor is located in the posterior fossa; its volume is 1.3 x 1.6 cm. The left trigeminal nerve inside the tumor is no longer distinguishable. Additionally, a compression of the pons as well as the left cerebral peduncle in the ponto-mesencephalic junction can be seen. The part of the tumor in the middle fossa has contact with the C2-C5 segments of the left internal carotid artery
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F1
An MRI revealed a tumor in the left Meckel's cave, with partial compression of the trigeminal nerve and extension to the posterior cranial fossa [Figure 1a]. However, the patient was re-admitted to the hospital 1 year later, in 2008, because of progressive clinical disturbance and increased volume of the lesion seen in follow-up MRI scans [Figure 1b], and a decision for re-operation was made.
(a and b) Pathology photomicrographs with hematoxylin-eosin, showing Zellballen architecture, numerous sinusoidal vessels (a, x40; b, x100). (c) Positive immunohistochemical profile of neuron-specific enolase (NSE) for chief cells (x100). (d) Positive immunohistochemical profile of neurofilament (NF) proteins for chief cells (x100). (e) Gomori reticulin stain showing the septae delineating Zellballen (x100). (f) Elevated Ki67/MIB1 labeling index. Higher magnification in the inset (x100)
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F2
The histopathologic examination of the specimen [Figure 2a-f] showed fragments of well-organized, compacted and nested epitheloid cells of the tumor dispersed in lobules (Zellballen architecture, composed of nests of polygonal chief cells enclosed by trabecula of fibrous and sustentacular elongated cells) which were histologically and immunohistochemically classified as a paraganglioma (WHO grade I). In addition to the examination of hematoxylin and eosin-stained tumor tissue [ Figure 2a and b], an immunohistochemistry investigation was performed. NSE immunoreactivity was strongly positive [Figure 2c]. Immunostaining for NF was also positive [Figure 2d]. Gomori reticulin stain showed septae delineating Zellballen [Figure 2e]. Ki-67/MIB-1 staining [Figure 2f]. Ki-67/MIB-1 expression levels were similar in all primary and recurrent tumor specimens.
Pre-operative axial T1-weighted MRI with contrast media, axial T2-weighted MRI, and coronal T1-weighted contrast-enhanced MRI show a markedly enhanced lesion located at the site of the previously removed tumor in Meckel's cave
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Five months after the second surgical intervention, in 2009, another local recurrence of the tumor was diagnosed in a follow-up MRI [Figure 3].
Transmission electron microscopy shows identification of neurosecretory granules (arrow) in chief cells. Higher magnification in the inset
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Tokyo, Japan). The ultrathin sections permitted the identification of neurosecretory granules, which are the distinctive ultrastructural feature of chief cells and confirmed the diagnosis of paraganglioma in this case [Figure 4].