title: Mural nodule of 10 mm or larger as predictor of malignancy for intraductal papillary mucinous neoplasm of the pancreas: Pathological and radiological evaluations.
abstract: BACKGROUND
  We had previously reported that mural nodule (MN) ≥10 mm was optimal predictor of malignancy for intraductal papillary mucinous neoplasm (IPMN). However, little is known about its microscopic findings and imaging detectability.
  
  
  METHODS
  Medical records and resected specimens of consecutive patients with IPMNs harboring MN ≥ 10 mm were reviewed. Imaging detectability was determined on reports basis. Malignant IPMNs (noninvasive + invasive carcinomas) were microscopically classified according to localization of high-grade dysplasia (HGD) within MN.
  
  
  RESULTS
  Thirty-six patients were included. Imaging detectability of MN ≥ 10 mm in CT, MRI, US and EUS were 64%, 68%, 89%, and 97%, respectively. Thirty-three (92%) IPMNs were histologically diagnosed as malignant. Thirty percent of malignant IPMNs were classified into "diffuse HGD within MN", 40% into "focal HGD within MN", and 30% into "HGD outside MN", in which HGD was not located within MN but in low papillary epithelia around MN. Overall sensitivity of pancreatic juice cytology was calculated as 58%, and for "diffuse HGD within MN", "focal HGD within MN", and "HGD outside MN" as 80%, 62%, and 30%, respectively (p = 0.0237). Univariate-analysis showed localization of HGD within MN was associated with true positive cytology (OR = 5.33, p = 0.043).
  
  
  CONCLUSIONS
  Detectability of MN ≥ 10 mm is excellent in US and EUS. Although HGD is observed within MN in 70% of malignant IPMNs, HGD is located only in low papillary epithelia around MN in the remaining 30%, in which sensitivity of pancreatic juice cytology is shown to be inadequate.
authors.affiliation: Department of Pathology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Japan; Department of Hepatopancreatobiliary Medicine, Kanazawa Medical University, Japan. Electronic address: natz.kawada@gmail.com.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Kawada
authors.affiliation: Department of Gastroenterology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Uehara
authors.affiliation: Department of Pathology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Japan.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Nagata
authors.affiliation: Department of Hepatopancreatobiliary Medicine, Kanazawa Medical University, Japan.
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Tsuchishima
authors.affiliation: Department of Hepatopancreatobiliary Medicine, Kanazawa Medical University, Japan.
authors.forename: Mikihiro
authors.initials: M
authors.lastname: Tsutsumi
authors.affiliation: Department of Pathology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Tomita
mesh_terms: D000328:Adult; D000368:Aged; D019160:Endosonography; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010183:Pancreatic Ducts / Q000000981:diagnostic imaging / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
keywords: EUS; Histological subtype; IPMN; Imaging detectability; Indication for resection; Mural nodule