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Lee, Park, and Lee: Ancient Schwannoma of the Thigh mimicking a Plexiform Malignant Peripheral Nerve Sheath Tumor: A Case Report
Case Report
Journal of the Korean Society of Magnetic Resonance in Medicine

Journal of the Korean Society of Magnetic Resonance in Medicine 2011; 15(2): 170-175.

Published online: 31 August 2011

DOI: https://doi.org/10.13104/jksmrm.2011.15.2.170

Ancient Schwannoma of the Thigh mimicking a Plexiform Malignant Peripheral Nerve Sheath Tumor: A Case Report

Yeon Soo Lee1, Sang Eun Park2, Jung Uee Lee3

1Department of Radiology, Daejeon St. Mary's Hospital, The Catholic University of Korea, Korea.

2Department of Orthopedic Surgery, Daejeon St. Mary's Hospital, The Catholic University of Korea, Korea.

3Department of Pathology, Daejeon St. Mary's Hospital, The Catholic University of Korea, Korea.

Corresponding author: Yeon Soo Lee, M.D., Department of Radiology, Daejeon St. Mary' Hospital, The Catholic University of Korea, 520-2, Deaheung-dong, Jung-gu, Daejeon 301-723, Korea. Tel. 82-42-220-9644, Fax. 82-42-220-9087, yslee1074@medimail.co.kr

Received 30 May 2011       Revised 22 July 2011       Accepted 28 July 2011

Copyright © 2011 Korean Society of Magnetic Resonance in Medicine

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Ancient schwannoma is a rare variant of schwannoma and a slow growing benign tumor associated with degeneration that may be diagnosed as a malignant tumor, because it presents with a large size and an inhomogeneous signal intensity. The main differential diagnosis of plexiform soft tissue tumor includes plexiform neurofibroma, malignant peripheral nerve sheath tumor (MPNST). In this case, we describe the MRI findings in a case of ancient schwannoma involving left thigh of a 63-year-old woman mimicking a plexiform MPNST. The tumor appeared as an inhomogeneous signal intensity and multinodular appearance, causing misdiagnosis as a plexiform MPNST.

Keywords: Schwannoma, Plexiform, Thigh, Magnetic resonance (MR)

Figures and Tables

Fig. 1
Plain lateral radiograph of the left femur shows a noncalcified soft tissue mass (arrows) in the posterior thigh.
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Fig. 2
Sagittal fat suppressed T2-weighted (a) and coronal T2-weighted (b) MR images show heterogeneous signal intensity mass (white arrow) associated with the multinodular, non fat-suppressed high signal lesions with proximal and distal extension in the sciatic nerve (arrows). The mass shows heterogeneous low signal intensity with mixed high signal intensity and peripheral dark signal rim (white arrow) on coronal T2 and T1-weighted image (b, c). Longitudinal extension of the low signal intensity fusiform or multinodular lesions adjacent to the mass along the sciatic nerve (arrows) on coronal T1-weighted image. Contrast enhanced coronal fat suppressed T1-weighted image (d) shows heterogeneous nodular and peripheral enhancement of the mass including non enhanced focus. However, plexiform-multinodular lesions along the sciatic nerve show no enhancement (white arrows).
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Fig. 3
Intraoperative photograph demonstrates an encapsulated mass (white arrows) associated with proximal extending multinodular yellowish lesion (black arrows) involving the sciatic nerve.
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Fig. 4
Photomicrograph of the encapsulated mass demonstrates hemorrhage (a), fibrosis (b), myxoid change and inflammatory cell infiltrate (hematoxylin and eosin staining, ×100). This tumor is positive immunostaining for S100 protein (c).
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Fig. 5
Photomicrograph of multinodular yellowish lesion shows myxoid change and inflammatory cell infiltrate (arrows) in the nerve tissue (hematoxylin and eosin staining, ×100).
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