PMC4533480_01
Axial computed tomography scan showing an isodense subcutaneous mass associated with irregular deformities in the outer surface of the adjacent occipital bone (arrow).
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F1
Cranial computed tomography showed an isodense mass located subcutaneously associated with irregular deformities in the outer surface of the adjacent occipital bone (Fig. 1).
Sagittal T1-weighted (A) and axial T2-weighted (B) magnetic resonance (MR) images showing a hypointense epicranial tumor, 7.5 x 5.5 cm in diameter, and axial (C) and sagittal (D) T1-weighted MR images after gadolinium infusion showing intense tumor enhancement.
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F2
No concurrent intracranial or orbital tumor was found (Fig. 2).
Intraoperative photograph demonstrating the subcutaneous mass dissected circumferentially. L: left, R: right, S: superior.
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F3
The subcutaneous tumor was elastic, soft, well circumscribed, entirely encapsulated, and less vascular, with firm adhesion to the periosteum, so was dissected circumferentially and resected en bloc (Fig. 3).
Photomicrographs of the resected tumor showing spindle-shaped cells with round or fusiform nuclei and eosinophilic cytoplasm within a matrix of fine fibrillary collagen, without findings of cell atypia, endothelial proliferation, or intratumoral hemorrhage (A: hematoxylin and eosin [HE] stain). Immunohistochemical staining for tumor cells was positive for S-100 protein (B), but negative for CD34 (C). Ki-67 labeling index was less than 1% (D). Original magnification x50 (A-D). A: HE, x50; B: S-100, x50; C: CD 34, x50; D: MIB-1< 1%.
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F4
No cell atypia, endothelial proliferation, or intratumoral hemorrhage was found (Fig. 4).
A: Genomic exploration by the single nucleotide polymorphism identification method showing abnormal gains in NF1 gene (17q11.2) (arrows). B: Immunohistochemical staining for neurofibromin demonstrating negative staining. Original magnification x10.
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F5
NF1 gene (Fig. 5A). Immunohistochemical staining for neurofibromin, a protein coded on 17q11.2, was absent (Fig. 5B). No abnormalities in the neurofibromatosis type 2 (NF2) gene, located on the 22q11.23, were found.