PMC5525461_01
T1-weighted, gadolium-enhanced MR images; a sagittal image shows a homogenously enhanced mass at the ventral foramen magnum, whose size is around 20 mm in diameter (a). On axial image, the tumor seemed to be attached to dura mater around C2. The tumor severely compressed the ventral medulla oblongata. (b and c) The axial, T2-weighted MR image showed no medullary edema (d)
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F1
T1-weighted magnetic resonance imaging (MRI) with gadolinium enhancement revealed a well-demarcated, solid mass at the ventral foramen magnum that was compressing the patient's medulla oblongata [Figure 1a-c]. A T2-weighted MRI showed no apparent edema inside the medulla [Figure 1d].
After opening the dura, the tumor, covered by the arachnoid, was identified. The tumor compressed the medulla (a). It had no severe adhesion to the brain stem or any cranial nerves. When approaching the tumor to detach it from the dura, massive hemorrhaging occurred that was difficult to control (b). After cutting the main feeder from the direction of the dura, the tumor became white and easy to manage. The whole dural attachment of the tumor was detached. Plate c shows the final view, after gross total removal of the tumor was achieved (Simpson Grade 2)
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F2
The tumor was gross totally removed (Simpson's grade 2) [Figure 2].
(a) Hematoxylin-eosin staining showing hypercellular tumor with staghorn appearance (arrow) (original magnification x10). (b) The arrow showed mitosis. (original magnification x40). (c) Ki-67 expressed in the HPC, nucleus positive, positive cells were less than 3% (original magnification x40). (d) The tumor was negative for EMA staining (original magnification x40)
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F3
Histologically, the tumor cells had high, dense nuclear, and branching vessels inside the tumors producing a staghorn appearance [Figure 3a and b]. The Ki-67 proliferation labelling index was less than 3% [Figure 3c and d].
No residual tumor in the images
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F4
Postoperative MRI showed no residual or occurrence of the tumor [Figure 4].