A Rare Case of Retroperitoneal Schwannoma in an Adult Male

Abstract

Objective: This study aims to illustrate a rare case of retroperitoneal schwannoma by presenting the clinical, imaging, and histological parameters.

Case report: A 36-year-old patient visited the outpatient clinic because of back pain experienced over the previous two months. There were no complaints regarding the nervous system or urinary system. Thorough imaging evaluation, including magnetic resonance for the lumbar spine, abdominal computed tomography, and positron emission tomography was conducted. An encapsulated mass was found in the retroperitoneal area, positioned in front of the O4 vertebra and in close proximity to the left psoas muscle, the left common iliac artery, and the left ureter. The lesion exhibited FDG radioisotope uptake, and a CT-guided biopsy confirmed a benign peripheral nerve tumor. The patient underwent laparotomy surgery, where the tumor was removed. The histological investigation, along with immunohistochemistry, confirmed the presence of a retroperitoneal schwannoma.

Conclusion: Schwannoma is a rare type of retroperitoneal tumor, with nonspecific clinical and radiological characteristics that make diagnosis difficult. Surgical resection is the primary treatment for symptomatic patients, with a favorable prognosis. Long-term follow-up is advised to reduce the chance of late recurrence.

Keywords: Case Report; Nerve Sheaths; Retroperitoneal Schwannoma; Retroperitoneal Tumor; Schwann Cells.

Figure 1

Sagittal lumbar MRI without contrast. A well-circumscribed lesion with signal isointense to the muscle in T1 weighed images (Panel A) and hyperintense signal in T2 weighed images (Panel B).

Figure 2

Computed tomography (CT) of the abdomen with intravenous contrast in coronal (A) and axial (B) sections. (A-B) A well-circumscribed mass with heterogeneous contrast enhancement, located anterior to the L4 vertebra, abutting the left ureter and left common iliac artery.

Figure 3

The surgical specimen. Macroscopic examination of the surgical specimen revealed a well circumscribed tumor, encased in a fibrous capsule and surrounded by fatty tissue.

Figure 4

Histopathology of the surgical specimen. A well-circumscribed nodular mass, encased in a fibrous capsule (panel A - thin black arrow). The lesion consists of hypercellular areas (Antoni A areas- bottom white arrow), and hypocellular areas (panel A - Antoni B areas - top white arrow) (magnification ×100). Microscopic image of a hypercellular – Antoni A area (panel B) (magnification × 200).