title: Hemorrhagic, calcified, and ossified benign retroperitoneal schwannoma: First case report.
abstract: BACKGROUND
  Schwannomas are mesenchymal tumors arising from the neural sheaths of peripheral nerves. They can almost develop in any part of the body, while head, neck and extremities are the most common sites. Occurrence in the retroperitoneum is rare. Schwannomas can show secondary degenerative changes including cyst formation, hyalinization, hemorrhage, and calcification, whereas the ossified retroperitoneal schwannoma was only reported in a malignant one.
  
  
  METHODS
  We first present a benign ossified retroperitoneal schwannoma in a 61-year-old female. The mass was found by a routine health examination. Computed tomography (CT) and magnetic resonance imaging (MRI) showed a well-defined mass in the area among duodenum, right liver, and kidney. Definitive preoperative diagnosis of the mass was difficult. By laparotomy, the mass was found in the retroperitoneum. We completely removed the tumor and gross specimen showed a mass with a capsule and 6 × 6 × 4.8 cm in size. Microscopic examination showed the tumor is composed of spindle-shaped cells with degenerative changes of hemorrhage, calcification, and ossification. Immunohistochemically, S-100 protein was strongly positive. Finally, the mass was diagnosed as a hemorrhagic, calcified, and ossified benign schwannoma in the retroperitoneum. The patient was followed up for a period of 21 months, during which she was well with no evidence of recurrence.
  
  
  CONCLUSIONS
  We report the first case of a benign retroperitoneal schwannoma with secondary degenerative changes including hemorrhage, calcification, and ossification. Precise preoperative diagnosis of the tumor is challenging even with multiple preoperative imaging modalities. After complete resection, patients with benign retroperitoneal schwanommas generally have good prognosis.
authors.affiliation: Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health Key Laboratory of Organ Transplantation Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases Department of pathology, First Affiliated Hospital, School of Medicine, Zhejiang University, Zhejiang Province, Hangzhou,China.
authors.forename: Shao-Yan
authors.initials: SY
authors.lastname: Xu
authors.forename: Ke
authors.initials: K
authors.lastname: Sun
authors.forename: Hai-Yang
authors.initials: HY
authors.lastname: Xie
authors.forename: Lin
authors.initials: L
authors.lastname: Zhou
authors.forename: Shu-Sen
authors.initials: SS
authors.lastname: Zheng
authors.forename: Wei-Lin
authors.initials: WL
authors.lastname: Wang
mesh_terms: D002114:Calcinosis / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D005260:Female; D006470:Hemorrhage / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D006801:Humans; D033162:Incidental Findings; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009442:Neurilemmoma / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D009999:Ossification, Heterotopic / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D012186:Retroperitoneal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D014057:Tomography, X-Ray Computed