title: Pelvic retroperitoneal pleomorphic hyalinizing angiectatic tumor (PHAT) of soft tissue: a case report.
abstract: BACKGROUND
  Pleomorphic hyalinizing angiectatic tumor (PHAT) is a rare soft tissue tumor of low malignant potential, which most often arises in the lower extremities. Lesions occurred in other anatomic locations have been rarely reported. Moreover, their imaging features have not been well discussed. Here we report a case of PHAT arising primarily in the pelvic retroperitoneum. To our knowledge, this is the first radiological description for retroperitoneum PHAT.
  
  
  METHODS
  A 26-year-old female was referred to our hospital for evaluation of a pelvic mass incidentally noted in routine pre-pregnancy ultrasonography examination. Magnetic resonance imaging (MRI) and computed tomography (CT) scan revealed an irregular mass with clear boundary in the pelvic retroperitoneum. Its signal intensity or density was inhomogeneous. On MRI images, it mainly showed isointense and slight hypointense on T1 weighted image and isointense and hyperintense on T2 weighted image. On contrast-enhanced images, it showed marked but heterogenous enhancement. With the delay time increasing, the enhanced area in the lesion increased but the CT value decreased. Dilated vessels and hemorrhage were detected in the tumor. With patience and careful separation, it was completely excised with great amount of bleeding during operation. Pathological and immunohistochemistry analysis confirmed the diagnosis of PHAT of the soft parts. We found no evidence of recurrence 18 months after operation.
  
  
  CONCLUSIONS
  We present an extremely rare case of PHAT arising primarily in the pelvic retroperitoneum. To our knowledge, this is the first radiological description for retroperitoneum PHAT. The provided information is useful for summarizing the characteristics of this kind of tumor. It should be included in the differential diagnosis of a well-defined, inhomogenously enhanced hypervascular soft-tissue mass in pelvic cavity.
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1# Youyi street, Chongqing, 400016, China.
authors.forename: Zhi-gang
authors.initials: ZG
authors.lastname: Chu
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1# Youyi street, Chongqing, 400016, China.
authors.forename: Meng-qi
authors.initials: MQ
authors.lastname: Liu
authors.affiliation: Department of Stomatology, The First Affiliated Hospital of Chongqing Medical University, 1# Youyi street, Chongqing, 400016, China.
authors.forename: Zhi-yu
authors.initials: ZY
authors.lastname: Zhu
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1# Youyi street, Chongqing, 400016, China.
authors.forename: Fa-jin
authors.initials: FJ
authors.lastname: Lv
authors.affiliation: Department of Radiology, The First Affiliated Hospital of Chongqing Medical University, 1# Youyi street, Chongqing, 400016, China. cyscitg@163.com.
authors.forename: Yu
authors.initials: Y
authors.lastname: Ouyang
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D010388:Pelvis / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000601:surgery; D012983:Soft Tissue Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D014057:Tomography, X-Ray Computed
keywords: Computed tomography; Magnetic resonance imaging; Pleomorphic hyalinizing angiectatic tumor