PMC4306265_01
On dynamic CT examination, axial sections showed a characteristic contrast retention in the nodular lesions on the scalp. On the sections near vertex (A-C) and through the left ear (D-F) the lesions are hypodense in pre-contrast images (short arrows), there is central or eccentric contrast retention in the arterial series (long arrows) and heterogeneous hyperdensity in the venous series (thick arrows).
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Moreover, we found smaller multiple soft-tissue masses spreading on the left side of the scalp (Figure 1).
The demonstrative features revealed on reformatted and 3D CT images. A sagittal maximum intensity projection (MIP) reformatted image (A) revealed patchy enhancement at in the venous drainage areas (dashed-line area) around the concomitant arteries. On the series with an increased contrast dose (B-D), the location and distribution of soft tissue masses became clearer.
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When measuring the density of the lesion, we found that it had the same density as arteries in the arterial phase and the same density as veins in the venous phase (Figure 2).
In the superior, axial T2W MRI images (A, B) through the skull base and auricles, the lesion is isointense with respect to the scalp, there is no evidence of invasive or infiltrative growth pattern, and hypointense deposition due to slow flow. Signal loss in this lesion on SWI images (C, D) shows an intensely hypervascular nature of the tumor. The histologic sections (E, F) (H&E, E; x100, F; x400) revealed some vague papillary proliferations of epithelioid cells with fibrinous materials. The peripheral portions show fibroblastic proliferations with some metaplastic formation. In high-power view in f, there are vague papillary configurations of epitheloid endothelial cells with occasional distinctive nucleoli and vesicular nuclei.
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MRI images, the lesion was hyperintense when compared with the scalp and did not cause any lytic reactions within the external auditory canal or the cartilaginous tissue of the left ear. Moreover, there was no evidence of perilesional reactive changes (Figure 3).