Misdiagnosis of retroperitoneal schwannoma: A case report and literature review

Retroperitoneal schwannomas (RS) are exceedingly rare, accounting for 3% of schwannomas. The diagnosis of RS is extremely difficult based on imaging alone and is commonly misdiagnosed. Current evidence for misdiagnosis of RS comes from scattered case reports. We performed a literature review of the existing evidence on misdiagnosis of RS. In addition, we describe a rare case of RS masquerading as a small bowel gastrointestinal stromal tumor (GIST). A literature search was performed in the Medline, EMBASE, and Web of Science databases. Articles pertaining to misdiagnosis of RS on imaging were curated. Data points included patient demographics, imaging findings, and treatment. 46 patients from 43 case reports met inclusion criteria. Most commonly, RS were located in the pelvis and were misdiagnosed as adnexal masses (48%), either presenting with vague abdominal pain or incidentally discovered during pregnancy. Pelvic RS tumors tended to be larger with a mean size of 8.6cm. They were often cystic due to degeneration and mimicking ovarian tumors. RS also mimics tumors arising from adjacent organs including pancreas, liver, and kidney. In patients with previous history of cancer, most commonly testicular cancer, RS presents as necrotic lymph node metastasis. The majority of these patients received unnecessary radiation or chemotherapy. Universally, the imaging characteristics of RS were non-specific, making diagnosis difficult. Percutaneous biopsy rarely helped clinch the diagnosis prior to surgical extirpation. RS is extremely difficult to diagnose preoperatively based on imaging. Our comprehensive summary may help surgeons better understand the common scenarios of misdiagnosis of RS.