[Morphology of gastrointestinal stromal tumors in advanced stages of the disease: baseline findings before chemotherapy with imatinib].
OBJECTIVE
Gastrointestinal stromal tumors (GISTs) are rare tumors of the gastrointestinal tract with an increasing detection rate due to improved differentiating methods in current diagnostic pathology. This study evaluates the radiologic characteristics of these neoplasms to discover specific signs leading to an earlier diagnosis.


METHODS
As part of a randomized phase III clinical trial of the European Organization for Research and Treatment of Cancer (EORTC), 72 patients with advanced stage GIST were treated with the selective tyrosine-kinase-inhibitor imatinib (Glivec, Novartis, Switzerland). For initial staging, 60 patients underwent MRI and 12 patients underwent CT.


RESULTS
GISTs are mesenchymal tumors that grow submucosally and exophytically and become multiple, nodular or ovoid in the advanced stage. The predominant findings are peripheral solid structures with strong contrast enhancement and a central necrosis. Metastases are primarily located in the liver, where they appear as oval or round, sharply delineated solitary lesions with central necrosis. CT demonstrates the primary tumors and local recurrences as nearly isodense with the liver. On MRI, the lesions are hypointense on T 1 -weighted sequences and hyperintense on T 2 -weighted sequences, compared to the liver.


CONCLUSIONS
Immunopathology now enables the exact histologic separation of GISTs from other mesenchymal tumors. The radiological morphology is not sufficiently specific to differentiate GISTs from other mesenchymal tumors. In view of new therapeutic options, cognizance of their typical manifestations is of increasing importance for radiologists.
Jost
D
D
Klinik und Poliklinik für Strahlenheilkunde, Universitätsklinikum Charité, Campus-Buch, Robert-Roessle-Klinik im Helios-Klinikum-Berlin, Berlin. jostdominik@gmx.de
Stroszczynski
C
C
Chmelik
P
P
Gaffke
G
G
Schlecht
I
I
Pink
D
D
Reichardt
P
P
Schneider
U
U
Hohenberger
P
P
Felix
R
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001549:Benzamides; D017024:Chemotherapy, Adjuvant; D003287:Contrast Media / Q000008:administration & dosage; D004064:Digestive System / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D005770:Gastrointestinal Neoplasms / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology / Q000601:surgery; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D000068877:Imatinib Mesylate; D008099:Liver / Q000473:pathology; D008113:Liver Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology / Q000556:secondary*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000188:drug therapy / Q000473:pathology; D009367:Neoplasm Staging; D018301:Neoplasms, Mesothelial / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology / Q000601:surgery; D010879:Piperazines / Q000627:therapeutic use*; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis; D011743:Pyrimidines / Q000627:therapeutic use*; D014057:Tomography, X-Ray Computed
D001549:Benzamides; D003287:Contrast Media; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit