PMC10073555_01
Sagittal T2W fat-suppressed image (A), transverse T2W image (B), transverse FLAIR image (C), transverse T2*W image (D), transverse T1W image (E), and transverse post-contrast T1W image (F). There is a large, strongly contrast-enhancing intra-axial mass [white arrowheads, (A-F)] expanding the brainstem with resultant perilesional edema [black arrowhead, (A)]. Note the multiple regions of the signal void within the mass in (D). The mesencephalic aqueduct is dorsally displaced and compressed by the mass [white arrow, (F)]. The lateral ventricles are mildly asymmetrically dilated in (B-F).
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F1
MRI revealed a strongly contrast-enhancing intra-axial mass expanding the brainstem, which was heterogeneously T2W and FLAIR isointense to hyperintense and T1W isointense to hypointense compared to white matter (Figure 1). Multiple T2*W signal voids were identified within the mass, suggestive of hemorrhage (Figure 1). T2W and FLAIR hyperintense, presumed to represent mild perilesional edema (Figure 1). This mass caused the compression of the cerebellum, narrowing and right dorsal lateral displacement of the mesencephalic aqueduct, and dilation of the ventricular system rostral to the compression (obstructive hydrocephalus) (Figure 1).
The transverse section of the pons shows a focal, large, bulging hemorrhagic predominantly left-sided mass (1 cm).
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F2
A cut section revealed a 1.1 x 1.0 x 0.8-cm gelatinous, soft, well-circumscribed, left-sided mass extended from the crus cerebri of the midbrain caudally to the pons (Figure 2). The tumor effaced part of the reticular formation and the longitudinal fibers of the pons (Figure 2), accounting for the circling (compulsive gait), dull mentation, and proprioceptive ataxia.
Hemangioblastoma with a prominent network of congested capillary vessels and stellate interstitial cells; 20 mum scale bar, H&E, 40x.
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F3
The neoplasm was composed of an interstitial population of cells located between a prominent, congested capillary network (Figure 3).
Neuron-specific enolase immunolabels the cytoplasm of the widely dispersed interstitial cells, clarifying cell shapes and sizes; 20 mum scale bar NSE, 40x.
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F4
NSE immunohistochemistry of the interstitial cells had strong, diffuse, intracytoplasmic immunolabeling, and clarified the cell shape and size (Figure 4).
von Willebrand factor immunolabels the capillary endothelial cell cytoplasm of the capillaries, with negative interstitial cells (red circles); 20 mum scale bar vWF, 40x.
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F5
Vascular endothelial cells had strong, diffuse, intracytoplasmic immunolabeling for vWF (Figure 5).
Glial fibrillary acidic protein variably immunolabels the cytoplasm of the interstitial cells; 20 mum scale bar GFAP, 40x.
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F6
Interstitial cells also had variably positive intracytoplasmic immunolabeling for GFAP (Figure 6).