Giant Intraosseous Schwannoma of the Ileopubic Ramus

Abstract

Schwannomas are the most common tumors of the peripheral nerves. Intraosseous schwannoma is a rare entity; approximately 200 cases are described in the world literature, with only 1 involving the ileopubic ramus. To the authors' knowledge, this article is the first to describe a giant intraosseous schwannoma of the ileopubic ramus, its clinical presentation and radiographic aspect, its histological findings, its biological behavior, and the differential diagnosis. It is also the first to describe surgical treatment of this entity. A 63-year-old woman presented with paroxysmal pain at the right groin. Radiographs showed a multilocular lytic lesion of the right ileopubic ramus, extending from the acetabulum to the pubic symphysis. Magnetic resonance imaging revealed extraosseous extension in the pelvis and in the anteromedial region of the right thigh. An incisional biopsy revealed fibroconnective tissue with sparse spindle cells in a myxoid stroma; diffuse expression of S100 protein was observed by immunohistochemistry. Intraosseous neurofibroma was the first histopathologic diagnosis. The 12×8×4-cm lesion was entirely removed via a Letournel ileoinguinal approach. Reconstruction of the ileopubic ramus was performed with an autologous bone graft taken from the omolateral iliac crest and fixed by a pelvic reconstruction plate. Histopathological examination revealed Antoni A and B patterns with Verocay bodies, no mitosis or cellular atypia, and diffuse expression of S100 protein by immunohistochemistry, all features indicative of a benign schwannoma. The patient returned to activities of daily living with no limitations. No recurrence had occurred 24 months postoperatively.

Management and retrospective analysis of pelvic ramus tumors and tumor-like lesions: Evaluation with 31 cases

“…In the literature, benign tumors such as chondromyxoid fibroma, intraosseous schwannoma, extracranial meningioma, ABC, simple bone cyst, GCT, and OC localized to the pelvic ramus have been reported. [2,4,11,15,16,18,19] In the present study, there were also cases of enchondroma, fibrous dysplasia, LCH, and ossifying fibroma that we had not seen before in the literature. In addition, tumor-like lesions such as insufficiency fractures, brown tumors, and synchondrosis have been reported in the literature.…”

“…There are also case reports of benign or malignant tumors located in the ramus in the literature. [8][9][10][11][12][13][14][15][16][17][18][19][20] In the series of 24 tumor patients we reported, 50% of the tumors in the pelvic ramus were malignant.…”

“…[24] In recent years, case reports of benign or malignant tumors and tumor-like lesions located in the ramus ischium or pubic ramus have been reported. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] In this study, which included 31 cases, the statistical analysis of the data found that the lesions were located more frequently in the pubic ramus, and the lesions located in the ramus ischium were found to have significantly higher risk of malignancy than tumor-like lesions.…”

“…[ 10 , 15 ] Patients usually present with symptoms of inguinal pain, swelling, or both. [ 2 , 15 , 16 ] Examination findings usually include a mass or sensitivity in that area. Some patients are detected by coincidental lesions on radiographs.…”

“…Follow-up, excision/curettage + adjuvant therapies or en-bloc resection can be performed in benign tumors. [ 2 , 4 , 6 , 15 , 16 , 19 ] In malignant tumors and metastases, wide resection (en-bloc resection of the involved ramus section) and/or combinations of non-surgical medical treatments such as chemotherapy and radiotherapy are performed according to the type and stage of the tumor. [ 3 , 4 , 8 - 10 , 20 ]…”