PMC7573284_01
Post-contrast MRI (A-C) showing a large irregular mass with heterogeneous enhancement in the left frontal lobe with mild peritumoral edema. Plain CT demonstrating a large mass mixed hypo- and isodensity (D). Magnetic resonance venography showing no development was seen in the superior sagittal sinus of the frontal area (E). Diffusion tensor imaging showing compression, displacement, and partial interruption of nerve fibers in the lesion area (F). Postoperative CT (G) and MRI 7-days postoperatively (H,I) revealed that the lesion was completely removed with no signs of recurrence.
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F1
After gadolinium administration, obvious heterogenous enhancement was observed (Figures 1A-C). Computerized tomography (CT) showed a heterogeneous hypo-and isoindense mass in the left frontal lobe with a CT value of 15-37 HU (Figure 1D). Magnetic resonance venography indicated that the forehead sagittal sinus was not visible as it was compressed by the tumor (Figure 1E). Diffusion tensor imaging showed that the nerve fibers in the lesion area were compressed, displaced, and partially interrupted (Figure 1F). Postoperative CT (Figure 1G) and MRI 1 week postoperatively (Figures 1H,I) demonstrated that the lesion was completely removed, and no signs of recurrence were observed.
Light microscopic image showing a number of small, round, oval, undifferentiated cells, with intense staining of the nuclei and basophilic cytoplasm (A). Immunohistochemical staining showing positivity for CD99 (B). FISH revealing positive results for EWSR1 rearrangement as indicated by the separation of red and green signals (C,D).
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F2
Hematoxylin and eosin-stained paraffin sections predominantly showed closely packed small, round to oval, undifferentiated cells with hyperchromatic nuclei, increased mitotic activity, and little basophilic cytoplasm (Figure 2A). MAP-2, vimentin, synaptophysin, and the progesterone receptor, and was negative for TTF-1, CK-pan, CK5/6, CD56, CgA, LCA, S-100, glial fibrillary acidic protein, myeloperoxidase, MyoD1, NeuN, Olig-2, STAT6, and epithelial membrane antigen. Moreover, fluorescence in situ hybridization (FISH) with a EWSR1 break apart probe showed 41.0% of split signals, thereby confirming the diagnosis of ES/pPNETs (Figures 2C,D).