PMC4901813_01
Preoperative images. A skull X-ray with dynamic range compression (a), axial computed tomography of the skull (b), F-18 fluorodeoxyglucose positron emission tomography (c), axial T2-weighted imaging (d), and postcontrast T1-weighted imaging of the axial plane (e) and coronal plane (f). Arrows and arrowheads indicate the enhanced outer and inner membranous structures, respectively
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F1
A skull X-ray at the first hospital showed no bone defects or expansion; however, a skull X-ray with dynamic range compression modification showed a sunburst appearance on the left temporal bone [Figure 1a]. Computed tomography (CT) of the head also showed a sunburst appearance due to bony spicule formation in a soft mass that was attached to the surface of the left temporal bone, without osteolysis, bone expansion, or cortical destruction [Figure 1b]. F-18 fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) detected a highly-labeled extracranial mass lesion on the nonlabeled temporal bone without metastasis [Figure 1c]. The mass lesion exhibited isointensity on T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI) and was heterogeneously enhanced on the postcontrast T1WI [Figure 1d-f]. Postcontrast T1WI showed the enhancement of the outer and inner membranous structures that were connected to the pericranium [Figure 1e, f; arrows and arrowheads].
The histopathological features of the tumor. Hematoxylin and eosin staining of the tumor (a) and the outer surface of the temporal bone (b-d). The tumor infiltrated some of the marrow cavities (black arrows in [b]), but not others (white arrow in [b]). The tumor invaded the compact bone (c) and infiltrated the marrow cavities under the thin compact bone (d). The black arrowheads in (b-d) show the surface of the temporal bone. Scale bars: 50 mum (a, c, d); 200 mum (b)
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F2
The histopathological findings were consistent with Ewing's sarcoma [Figure 2a]. The tumor was positive for EWS-FLI-1 translocation. The tumor was mainly an extracranial mass that was attached to the outer surface of the temporal bone with bone reaction on the surface, and with local invasion into the temporal bone [Figure 2b-d]. It infiltrated into some marrow cavities under very thin compact bone [Figure 2b-d].