title: Imaging features of primary anorectal gastrointestinal stromal tumors with clinical and pathologic correlation.
abstract: OBJECTIVE
  To evaluate the imaging features of anorectal gastrointestinal stromal tumors (GISTs) with clinical and histopathologic correlation.
  
  
  METHODS
  In this Institutional Review Board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study, 16 patients (12 men; mean age 66 years (30-89 years)) with pathologically proven anorectal GISTs seen at our institution from January 2001 to July 2011 were identified. Electronic medical records were reviewed to obtain clinical data. Pretreatment imaging studies (computed tomography (CT) in 16 patients, magnetic resonance imaging (MRI) in 9 patients and fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT in 8 patients) were evaluated by 2 radiologists until consensus. The location, size and imaging features of the primary tumor and metastases at presentation, if any, were recorded, and correlated with clinical data and pathologic features (histologic type, presence of necrosis, mitotic activity, risk category, immunohistochemical profile).
  
  
  RESULTS
  The mean tumor size was 6.9 × 6.0 cm. Of the 16 tumors, 11 (68.7%) were infralevator, 4 (25%) supra and infralevator and 1 (6.3%) supralevator; 9 (56.2%) were exophytic, 6 (37.5%) both exophytic and intraluminal, and 1 (6.3%) was intraluminal. The tumors were iso- to minimally hypoattenuating to muscle on CT, iso- to minimally hypointense on T1-weighted images, hyperintense on T2-weighted images and showed variable enhancement. Necrosis was seen in 4 (25%), and hemorrhage and calcification in 2 (12.5%) patients each. The tumors were FDG avid with a mean maximum standardized uptake value of 11 (8.4-16.8). All tumors were positive for KIT and CD34. Distant metastasis to liver was seen in 1 patient (6.3%) at presentation.
  
  
  CONCLUSIONS
  Anorectal GISTs are well-circumscribed, non-circumferential, predominantly infralevator, intramural or exophytic, FDG-avid, hypoattenuating masses, and present without lymphadenopathy or intestinal obstruction.
authors: Department of Radiology, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.
authors: M R
authors: MR
authors: Koch
authors: J P
authors: JP
authors: Jagannathan
authors: A B
authors: AB
authors: Shinagare
authors: K M
authors: KM
authors: Krajewski
authors: C P
authors: CP
authors: Raut
authors: J L
authors: JL
authors: Hornick
authors: N H
authors: NH
authors: Ramaiya
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D005770:Gastrointestinal Neoplasms / Q000175:diagnosis* / Q000473:pathology; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
references: Dis Colon Rectum. 2006 May;49(5):609-15
references: 16552495
references: Hum Pathol. 1999 Oct;30(10):1213-20
references: 10534170
references: Am J Surg Pathol. 2006 Apr;30(4):477-89
references: 16625094
references: Am J Surg Pathol. 2001 Sep;25(9):1121-33
references: 11688571
references: J Clin Oncol. 2007 May 1;25(13):1753-9
references: 17470865
references: Ann Nucl Med. 2009 Jul;23(5):459-64
references: 19430859
references: Br J Radiol. 2000 Sep;73(873):1010-2
references: 11064658
references: J Clin Oncol. 2004 Sep 15;22(18):3813-25
references: 15365079
references: Am J Surg Pathol. 1999 Jan;23(1):82-7
references: 9888707
references: Radiographics. 2003 Mar-Apr;23(2):283-304, 456; quiz 532
references: 12640147
references: Am J Pathol. 1998 May;152(5):1259-69
references: 9588894
references: Eur J Gastroenterol Hepatol. 2001 Mar;13(3):283-6
references: 11293450
references: AJR Am J Roentgenol. 2003 Jun;180(6):1607-12
references: 12760929
references: Cell Tissue Res. 2009 Aug;337(2):197-212
references: 19506909
references: Eur Radiol. 2001;11(2):216-9
references: 11218017
references: Am J Surg Pathol. 1999 Aug;23(8):946-54
references: 10435565
references: Semin Diagn Pathol. 2006 May;23(2):70-83
references: 17193820
references: Hum Pathol. 2002 May;33(5):459-65
references: 12094370
references: Ann Surg. 2000 Jan;231(1):51-8
references: 10636102
references: N Engl J Med. 2002 Aug 15;347(7):472-80
references: 12181401
references: Am J Surg Pathol. 2005 Jan;29(1):52-68
references: 15613856