Case report

We present the case of a 63-year-old female with no relevant medical history who underwent an abdominal ultrasound due to a recent diagnosis of chronic hepatitis B. A large right paravertebral adrenal mass was observed and the patient was asymptomatic. Magnetic resonance imaging (MRI) identified a 12 cm heterogeneous retroperitoneal tumor in thoracoabdominal transition (Fig. 1). MRI could not properly determine its origin and an additional positron emission tomography (PET) did not provide more information.

Fig. 1 Image of a retroperitoneal schwannoma via nuclear magnetic imaging. 

Laparoscopic surgery was decided upon due to uncertain origin of the tumor and its large size. A 15 cm mass was observed that was located partially abdominal and thoracic, with displacement of the cava. The thoracic cavity needed to be accessed in order to complete the tumor resection. The anatomical pathology was compatible with schwannoma.

Discussion

Schwannoma should be considered in the differential diagnosis of mesenchymal tumors. Even though it is a benign entity, it has malignant potential and is associated with neurofibromatosis ^2,3,4. As the retroperitoneum is flexible, these tumors can reach large sizes without symptoms, as observed in our patient. Therefore, the diagnosis is usually incidental during imaging tests requested for other reasons ³.

Surgical resection with free margins is the treatment of choice for retroperitoneal schwannomas, with a low recurrence risk ^3,4,5. The definitive diagnosis is obtained via a histological study, including inmunohistochemistry. Schwannoma cells are positive for the S-100 protein, as seen in our patient ¹.