title: Hemangiopericytoma in the sacrococcygeal space: a case report.
abstract: BACKGROUND
  A hemangiopericytoma is a rare, soft-tissue tumor of vascular origin derived from a pericyte of Zimmerman, which is a modified smooth muscle cell that surrounds the small blood vessels. Hemangiopericytomas can occur wherever there are vascular capillaries. However, there are no previous reports of a hemangiopericytoma in the sacrococcygeal space.
  
  
  METHODS
  We describe the first reported case of a hemangiopericytoma found in the sacrococcygeal space. A 47-year-old Japanese woman presented with a palpable tumor on the left side of her anus. Preoperative imaging indicated that the tumor was in the sacrococcygeal space without invasion of other organs. A complete resection was performed via a parasacral incision. The histological and immunohistochemical staining patterns supported the diagnosis of a hemangiopericytoma.
  
  
  CONCLUSIONS
  A complete resection without piecemeal excision is the best way to treat a hemangiopericytoma. Recognizing the presence of a hemangiopericytoma in the sacrococcygeal space requires appropriate surgery.
authors.affiliation: Second Department of Surgery, Wakayama Medical University, School of Medicine, Kimiidera, Wakayama, 641-8510, Japan. yokoyama@wakayama-med.ac.jp.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kitahata
authors.forename: Shozo
authors.initials: S
authors.lastname: Yokoyama
authors.forename: Katsunari
authors.initials: K
authors.lastname: Takifuji
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Hotta
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsuda
authors.forename: Toshiji
authors.initials: T
authors.lastname: Tominaga
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Oku
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Junji
authors.initials: J
authors.lastname: Ieda
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yamaue