Intrapelvic sciatic notch schwannoma: microsurgical excision using the infragluteal approach

Case report

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Benign neurogenic tumors at the sciatic notch that are purely intrapelvic have rarely been reported. Because of this tumor's particular position, a transabdominal or combined transabdominal-gluteal approach is usually used to achieve total resection. However, the transabdominal approach carries a remarkable surgical risk because of the manipulation of intraperitoneal organs. Here, the authors describe a 59-year-old woman harboring a purely intrapelvic sciatic notch schwannoma extrinsic to the sciatic nerve, which was totally removed via the infragluteal approach preserving sciatic function. The postoperative course was uneventful. The infragluteal approach can be safely used for the effective resection of intrapelvic benign neurogenic tumors at the sciatic notch that are extrinsic to the sciatic nerve, avoiding the more invasive and risky transabdominal approach.

Article Information

Address correspondence to: Quintino Giorgio D'Alessandris, M.D., Department of Neurosurgery, Catholic University School of Medicine, Largo Agostino Gemelli, 8, Rome 00168, Italy. email:

Please include this information when citing this paper: published online April 12, 2013; DOI: 10.3171/2013.3.JNS121161.

© AANS, except where prohibited by US copyright law.



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    Axial (left) and coronal (right) pelvic CT scans showing an intrapelvic rounded mass at the entry of the left sciatic notch. Asterisks indicate tumor. AR = acetabular roof; Co = coccyx; GM = gluteus maximus; Gm = gluteus minimus; IA = internal iliac artery; IPs = iliopsoas muscle; IR = ischial ramus; Pi = piriformis muscle; PV = internal pudendal vein; RM = rectus abdominis muscle; Sa = sacrum.

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    Preoperative axial (A) and coronal (B) T2-weighted pelvic MR images showing a dishomogeneous hyperintense ovoid mass under the piriformis muscle at the left sciatic notch. Three-month postoperative axial (C) and coronal (D) T2-weighted pelvic MR images showing complete removal of the tumor and the normal course of sciatic nerve. Asterisks indicate tumor. AIIS = anterior inferior iliac spine; I = ilium; IT = ischial tuberosity; Me = mesentery; Re = rectum; SN = sciatic nerve; SP = sacral plexus.

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    High-magnification intraoperative views. A and B: Progressive dissection of the schwannoma. C: Complete tumor removal.

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    Photomicrographs obtained for pathological examination of the tumor. Left: The tumor is characterized by the presence of spindle cell areas (white asterisk) with palisaded arrangement and double rows of nuclei separated by eosinophilic material, termed “Verocay bodies” (inset), alternating with loosely textured areas (black asterisk) mimicking a neurofibroma. H & E, original magnification ×100. Right: On immunohistochemistry a diffuse and uniform nuclear and cytoplasmic staining for S100 protein was observed in all tumor cells, supporting the diagnosis of schwannoma. Original magnification ×100.

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    Schematic drawings of axial pelvic sections to show the relationships between the tumors and the width of the sciatic notch. A: Spinner et al. Case 1. B: Consales et al. case. C: The present case (as seen in Fig. 1 left). Notice that the sciatic notch (yellow oval) width was the smallest in the present case (6 cm vs 8.5 cm in the Spinner case and 6.5 cm in the Consales case). Asterisk indicates tumor (blue). Printed with the permission of Quintino Giorgio D'Alessandris, 2013.



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