title: Report of a case: Retroperitoneal mucinous cystadenocarcinoma with rapid progression.
abstract: BACKGROUND
  Retroperitoneal mucinous cystic neoplasms are uncommon, and little is known about the etiology of the disease. Malignant forms of these are extremely rare. Here, we report a case of primary retroperitoneal mucinous cystadenocarcinoma (PRMC), which demonstrated unexpectedly aggressive progression despite finding only a limited area of adenocarcinoma.
  
  
  METHODS
  A 62-year-old woman with a complaint of abdominal discomfort was admitted to the hospital. Abdominal CT and MRI showed multiple large retroperitoneal cysts dislocating the right kidney nearly to the center of the abdomen. Transabdominal resection of the cysts was performed. Those cysts contained 1100ml of mucinous fluids in total. Cytological examination of those fluids revealed no malignant cells. The cyst wall was lined with mucinous epithelial cells, and contained some ovarian-type stroma. Also, there was a focal area of adenocarcinoma in the cyst wall, and the lesion was diagnosed as primary retroperitoneal mucinous cystadenocarcinoma. Eight months later, the patient developed lumbar bone metastasis. Chemotherapy with S-1, an oral fluoropyrimidine, and docetaxel had been begun immediately; however, the disease had rapidly spread in the retroperitoneum. Eventually, the patient died of the disease 15 months after surgery.
  
  
  CONCLUSIONS
  Retroperitoneal mucinous cystic neoplasms are considered to be metaplasia of embryonal coelomic epithelium. Complete excision without rupture is essential. However, variance of biological aggressiveness might exist in PRMCs.
  
  
  CONCLUSIONS
  Retroperitoneal mucinous cystadenocarcinoma is a rare tumor, and it is urgently necessary to elucidate the etiology of an effective therapy for the disease.
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan. Electronic address: hkamiya@juntendo.ac.jp.
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Kamiyama
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Ai
authors.initials: A
authors.lastname: Shimazu
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Yurika
authors.initials: Y
authors.lastname: Makino
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Ichikawa
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Hobo
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Shuei
authors.initials: S
authors.lastname: Arima
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Shigeo
authors.initials: S
authors.lastname: Nohara
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Sugiyama
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Okumura
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Takei
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Miura
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Namekata
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Tsumura
authors.affiliation: Department of Pathology, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Motoi
authors.initials: M
authors.lastname: Okada
authors.affiliation: Department of Pathology, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Masaru
authors.initials: M
authors.lastname: Takase
authors.affiliation: Department of Surgery, Koshigaya Municipal Hospital, Higashikoshigaya 10-47-1, Koshigayashi, Saitama 343-8577, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Matsumoto
keywords: Metastasis; Mucinous cystadenocarcinoma; Mucinous cystic neoplasm; Primary retroperitoneal; Recurrence; mucinous cystadenocarcinoma