A giant pelvic infiltrating schwannoma misdiagnosed as an ovarian neoplasm that was resected using a laparoscopic approach: A case report

Abstract

Introduction and importance: Large retroperitoneal schwannomas are rare and present significant challenges in surgical management, particularly when located in the pelvic region. Gynecologists can encounter rare problems when a pelvic schwannoma is mistaken for an adnexal pathology. Case Presentation: A 62-year-old woman presented with a giant retroperitoneal mass suspected of a potentially malignant ovarian tumor preoperatively. Computed tomography revealed a large mixed solid-cystic mass near the right adnexa measuring 118 × 100 × 80 mm. The cancer antigen 125 level was 196 U/mL. We performed a diagnostic-operative laparoscopy, which showed a retroperitoneal neoformation below the cava and aortic bifurcation adherent to the sacrum, right pelvic vessels, and hypogastric nerve up to the vagina. We carefully detached the mass from the nearby tissues using the most appropriate laparoscopic devices. The entire neoplasm was removed through the vagina into a surgical bag. The surgery lasted 180 min without complications. Histology revealed a grade I benign schwannoma. At the 12-month follow-up, the patient was asymptomatic without signs of recurrence. Clinical Discussion: Pelvic retroperitoneal schwannomas can mimic ovarian carcinomas; misdiagnosis may occur due to their rarity and the difficulty of interpreting preoperative imaging. In case of unexpected giant presacral schwannomas surgical management is challenging due to their peculiar location. Conclusion: This case underscores the need for a skilled, experienced team of gynecological oncologists to achieve favorable outcomes when performing laparoscopic surgery of giant pelvic retroperitoneal schwannoma. Adequate knowledge of the complex pelvic anatomy, careful surgical planning, and familiarity with the most appropriate surgical tools are critical points.

Keywords: Laparoscopy; Large retroperitoneal mass; Minimally invasive surgery; Presacral space; Schwannoma.

Fig. 1

Computed tomography sagittal scan showing the large mixed solid cystic mass measuring approximately 118 × 100 × 80 mm extending from the right ovary and occupying the entire pelvis.

Fig. 2

The main steps of the surgical procedure: (a) identification of the mass attached to the right ovary; (b) visualization of the mass in the presacral space and identification of the right ureter that is moved up by the mass; (c) identification of the mass in the retroperitoneal presacral space below the cava bifurcation, with the aortic bifurcation clearly visible; (d–e) resection of the mass and placement in a surgical bag; and (f) view of the surgical bed after the resection of the mass.

Fig. 3

Histological examination of the resected mass. 1a (10×) and 1b (20×): hematoxylin and eosin staining showed two patterns of alternating Antoni A and Antoni B areas; in Antoni A areas, compact spindle cells with indistinct cytoplasmic borders were arranged in short bundles or interlacing fascicles, whirling and sometimes ill-defined fascicles. Antoni B areas are less orderly and cellular with spindle or oval cells arranged haphazardly in the hyalinized matrix, collagen fibers, and inflammatory cells; mitotic figures were occasionally present. 1c (20×): the S100 protein is highly expressed in the schwannoma. 1d (20×): at immunohistochemistry, Ki67 is expressed in scattered tumoral cells.