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Imaging features of primary anorectal gastrointestinal stromal tumors with clinical and pathologic correlation.

Koch MR, Jagannathan JP, Shinagare AB, Krajewski KM, Raut CP, Hornick JL, Ramaiya NH - Cancer Imaging (2013)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.

ABSTRACT

Purpose: To evaluate the imaging features of anorectal gastrointestinal stromal tumors (GISTs) with clinical and histopathologic correlation.

Materials and 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.

Conclusion: Anorectal GISTs are well-circumscribed, non-circumferential, predominantly infralevator, intramural or exophytic, FDG-avid, hypoattenuating masses, and present without lymphadenopathy or intestinal obstruction.

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A 68-year-old man presented with acute severe pelvic pain. (a) Contrast-enhanced CT image in the axial plane showed a large cystic mass (arrow) with an air-fluid level (curved arrow), which was interpreted as a pelvic abscess and was drained. Pathology revealed a GIST. (b) T2-weighted MRI performed with an endorectal coil in the axial plane shows a large cystic mass with a peripheral rind of soft tissue (arrow) with central debris. A drainage catheter is seen in situ (arrowhead). Evaluation of a portion of the tumor abutting the endorectal coil is limited due to artifacts of the coil (long thin arrow).
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Figure 3: A 68-year-old man presented with acute severe pelvic pain. (a) Contrast-enhanced CT image in the axial plane showed a large cystic mass (arrow) with an air-fluid level (curved arrow), which was interpreted as a pelvic abscess and was drained. Pathology revealed a GIST. (b) T2-weighted MRI performed with an endorectal coil in the axial plane shows a large cystic mass with a peripheral rind of soft tissue (arrow) with central debris. A drainage catheter is seen in situ (arrowhead). Evaluation of a portion of the tumor abutting the endorectal coil is limited due to artifacts of the coil (long thin arrow).

Mentions: On MRI, most tumors were iso- to minimally hypointense to muscle on T1-weighted images and hyperintense on T2-weighted images. The presence of hemorrhage, seen as high signal intensity foci on the fat-suppressed T1-weighted images, was seen in 2 tumors. Post-gadolinium MRI images showed mild to moderate enhancement in all but 1 patient who showed avid enhancement (Table 2). The enhancement pattern was similar on CT and MRI. One anal tumor was very low in attenuation and thought to be an intersphincteric cyst (Fig. 1). In 1 patient, the tumor presented on CT as a large rim-enhancing mass with central low density and foci of air, and was initially thought to be a prostatic abscess. Percutaneous catheter drainage was attempted, returning only minimal blood-stained fluid. Subsequent endorectal MRI showed a large necrotic pelvis mass separate from the prostate displacing the rectum (Fig. 3). At surgery, there was extensive ulceration of the rectal mucosa, and the foci of air was thought to be secondary to fistulous communication with the rectum.Figure 3


Imaging features of primary anorectal gastrointestinal stromal tumors with clinical and pathologic correlation.

Koch MR, Jagannathan JP, Shinagare AB, Krajewski KM, Raut CP, Hornick JL, Ramaiya NH - Cancer Imaging (2013)

A 68-year-old man presented with acute severe pelvic pain. (a) Contrast-enhanced CT image in the axial plane showed a large cystic mass (arrow) with an air-fluid level (curved arrow), which was interpreted as a pelvic abscess and was drained. Pathology revealed a GIST. (b) T2-weighted MRI performed with an endorectal coil in the axial plane shows a large cystic mass with a peripheral rind of soft tissue (arrow) with central debris. A drainage catheter is seen in situ (arrowhead). Evaluation of a portion of the tumor abutting the endorectal coil is limited due to artifacts of the coil (long thin arrow).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3569670&req=5

Figure 3: A 68-year-old man presented with acute severe pelvic pain. (a) Contrast-enhanced CT image in the axial plane showed a large cystic mass (arrow) with an air-fluid level (curved arrow), which was interpreted as a pelvic abscess and was drained. Pathology revealed a GIST. (b) T2-weighted MRI performed with an endorectal coil in the axial plane shows a large cystic mass with a peripheral rind of soft tissue (arrow) with central debris. A drainage catheter is seen in situ (arrowhead). Evaluation of a portion of the tumor abutting the endorectal coil is limited due to artifacts of the coil (long thin arrow).
Mentions: On MRI, most tumors were iso- to minimally hypointense to muscle on T1-weighted images and hyperintense on T2-weighted images. The presence of hemorrhage, seen as high signal intensity foci on the fat-suppressed T1-weighted images, was seen in 2 tumors. Post-gadolinium MRI images showed mild to moderate enhancement in all but 1 patient who showed avid enhancement (Table 2). The enhancement pattern was similar on CT and MRI. One anal tumor was very low in attenuation and thought to be an intersphincteric cyst (Fig. 1). In 1 patient, the tumor presented on CT as a large rim-enhancing mass with central low density and foci of air, and was initially thought to be a prostatic abscess. Percutaneous catheter drainage was attempted, returning only minimal blood-stained fluid. Subsequent endorectal MRI showed a large necrotic pelvis mass separate from the prostate displacing the rectum (Fig. 3). At surgery, there was extensive ulceration of the rectal mucosa, and the foci of air was thought to be secondary to fistulous communication with the rectum.Figure 3

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.

ABSTRACT

Purpose: To evaluate the imaging features of anorectal gastrointestinal stromal tumors (GISTs) with clinical and histopathologic correlation.

Materials and 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.

Conclusion: Anorectal GISTs are well-circumscribed, non-circumferential, predominantly infralevator, intramural or exophytic, FDG-avid, hypoattenuating masses, and present without lymphadenopathy or intestinal obstruction.

Show MeSH
Related in: MedlinePlus