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

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.

CT Features of Colorectal Schwannomas: Differentiation from Gastrointestinal Stromal Tumors

“…Conversely, in malignant tumors such as GISTs, the speed of tumor growth often outstrips neovascularization and leads to central necrosis. Several previous reports indicate 37.5%-81.8% of rectal GISTs show heterogeneous enhancement with internal hemorrhage or necrosis [10, 11]. Indeed, half of GISTs (10/21, 47.6%) in our study had intra-tumoral necrosis.…”

“…Several pathologists insist that lymphoid cuffing might be the result of cytokines systemically secreted by tumor cells that induce the chemokinesis of lymphocytes [1, 13]. Contrary to schwannoma, it is well-known that GISTs seldom accompany with LN metastasis [10, 11]. Therefore, schwannoma should be first considered when we encounter a subepithelial mass with enlarged LNs in the colorectum.…”

MDCT and clinicopathological features of small bowel gastrointestinal stromal tumours in 102 patients: a single institute experience

“…A systematic review of all pre-treatment and followup CT studies was performed in consensus by two oncoradiology fellowship-trained radiologists (ADB and SHT) with 5 and 8 years' experience. A total of 803 CTs were reviewed (mean 5; range, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Imaging features of the primary tumour that were recorded included the site of origin in SB, largest dimension, margin (well circumscribed or ill defined/infiltrative), outline (smooth/ undulating or irregular/lobulated), growth pattern (exophytic, intraluminal or combined), tumour heterogeneity (homogeneous or heterogeneous), presence and percentage of cystic/necrotic component (Hounsfield units # 20), presence of calcifications and complications [tumour-bowel fistula (TBF), bowel obstruction or intraperitoneal rupture].…”

“…[12][13][14][15] In the past, our group has published the imaging features of GISTs arising at uncommon sites such as the oesophagus, duodenum and anorectal region. [16][17][18] To the best of our knowledge, there is no literature focusing dedicatedly on the imaging features of SB GISTs (excluding duodenal GISTs, which have a risk stratification different from jejunal and ileal GISTs). 8,19 Accordingly, the purpose of our study was to evaluate the clinical, pathological and imaging features of SB GISTs at presentation and their metastatic pattern.…”

Quantitative magnetization transfer MRI of desmoplasia in pancreatic ductal adenocarcinoma xenografts

“…The signal intensity from the off‐resonance saturation images ( M sat ) was normalized to that from the images without MT saturation ( M 0 ). Using the central slice through each tumor, regions of interest (ROIs) were drawn to encompass the PDAC xenograft tumor tissues while excluding areas of high signal intensity in MT‐weighted images indicative of tumor necrosis . Once defined on one M sat image, the ROI was then copied and applied to the corresponding M 0 and M sat images at all other offset frequencies.…”