PMC6595646_01
Left retroauricular lesion.
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A 16-year-old girl was referred to our service for a rapidly progressive left retroauricular lesion incidentally discovered 3 weeks earlier (Figure 1).
Preoperative noncontrast CT scan showing an ill-defined lesion with sunburst periosteal reaction over the left mastoid bone (arrows). (A) Axial view. (B) Coronal view. CT indicates computed tomography.
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An aggressive periosteal reaction with a sunburst appearance was also described (Figure 2).
Preoperative MRI. (A) Axial T1W1 with isointense signal lesion (asterisk). (B) Coronal T2W1 with hypointense signal lesion (arrow). MRI indicates magnetic resonance imaging.
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The lesion was strictly confined to the outer cortex of the temporal bone (Figure 3).
Left partial mastoidectomy with wide surgical margins. (A) Surgical deficit following complete en bloc resection of the tumour. (B) Pathological specimen.
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The patient had a left partial mastoidectomy with gross surgical margins between 1 and 1.5 cm (Figure 4).
Hematoxylin and eosin (HE) immunostaining. (A) Low power view showing a low-grade fibro-osseous lesion (HE40x). (B) Bland spindle cells in a fibrous background, with islands of woven bone (HE100x). (C) Focus of woven bone which appears to be partially surrounded by osteoblasts (HE200x). (D) Bland spindle cells in a fibrous background, with islands of woven bone (HE200x).
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Woven bone with only scant lamellar bone was noted and no prominent osteoblastic population were found along bone trabeculae (Figure 5).