Imaging, morphologic, and immunohistochemical correlation in gastrointestinal stromal tumors

Abstract

BACKGROUND Gastrointestinal stromal tumors (GISTs) recently have been distinguished morphologically, immunohistochemically, and genetically from other gastrointestinal‐tract spindle cell neoplasms. The objective of this study was to correlate clinical and imaging findings with morphology and immunohistochemistry to diagnose GISTs and to differentiate them from other spindle cell lesions in the gastrointestinal tract. METHODS The authors reviewed 9 patients who had tumors that were diagnosed as GIST by image‐guided and endosonographic‐guided fine‐needle aspiration (FNA) with or without core biopsy (7 stomach tumors and 2 intraabdominal tumors). The male:female ratio was 3:6, and the patients ranged in age from 38 years to 80 years. Onsite evaluation, preliminary cytologic evaluation, and immunohistochemistry were provided for 6 patients. Immunostains were performed, depending on sample size, on aspirates and/or core biopsies. RESULTS On imaging studies, most tumors were smooth and homogenous, consistent with GIST. Tumors ranged in size from 1.8 cm to 22 cm. The largest neoplasm showed solid/cystic and necrotic components. Aspirates consisted of spindle cell, neoplastic proliferation arranged in fascicles that exhibited focal, nuclear palisading; indistinct, cytoplasmic borders; and no significant atypia or mitosis. Focal epithelioid changes or cytologic atypia and mitoses were observed in 2 tumors. Immunostains revealed tumor expression of CD117 and/or CD34 in 5 of 6 tumors, expression of actin in 3 of 6 tumors, and expression of desmin in 1 of 6 tumors. All tumors were diagnosed as GIST (or consistent with GIST for tumors that lacked immunochemical analysis). Five patients underwent surgical excision, and the GIST diagnosis was confirmed in 3 patients, whereas 1 tumor proved to be neurofibroma, and another tumor was leiomyoma. No surgical follow‐up was available for the remaining 4 patients, who had imaging and morphologic findings consistent with GIST. CONCLUSIONS In the setting of consistent clinical and radiologic findings, the combined use of cytomorphology and immunohistochemistry on FNA and/or core biopsy in most instances provides a reliable pathologic diagnosis of GIST. The need of sufficient material for performing ancillary studies and the usual impossibility of excluding malignancy are limitations of FNA cytology of GIST. Cancer (Cancer Cytopathol) 2006. © 2006 American Cancer Society.

Multiple Primary Gastrointestinal Stromal Tumors Presenting in Jejunum and Ileum

“…Typically, primary GISTs are well-circumscribed highly vascular tumors arising from any viscera in the gastrointestinal tract and growing in an intraluminal or extraluminal manner; most GISTs, however, are predominantly exophytic [8,9]. The tumor capsule may have smooth, lobular, irregular, or invasive margins; nonetheless, most GISTs are small and have a well-delimited capsule with smooth or lobular margins [8][9][10][11][12]. Malignant GISTs might have invaded adjacent organs and mesenteric fat [12].…”

“…Consequently CT scans do not identify any lymphadenopathy [8][9][10]12]. Smaller GISTs have a homogeneous appearance; while larger GISTs are heterogeneous, have a cystic configuration with enhancing borders of variable thickness and irregular central areas of fluid, air, necrosis, or cavitations that communicate with the gastrointestinal lumen [2,8,[10][11][12]. The ileal GIST of this patient presented with characteristics of malignancy such as cystic degeneration with hemorrhagic and necrotic contents and perforation into the abdominal cavity with spillage of its contents.…”

Imatinib mesylate neoadjuvant treatment for rectal malignant gastrointestinal stromal tumor

“…EUSguided aspiration or core biopsy for submucosal tumors had a success rate of 60%-70% in the earlier studies, but this rate is now gradually reaching 80%-90%, which is significantly higher than that of a simple endoscopic biopsy [10][11][12] . The usefulness of biopsy in diagnosis can be enhanced by immunohistochemical staining on aspirates or tissues for tumor-specific markers such as CD117 and CD34, which are crucial for a diagnosis of GISTs [13] . Severe nuclear atypia and active mitotic figures indicating malignancy can help the decision in favor of a neoadjuvant therapy.…”

Gastrointestinal stromal tumor with a marked rotation

“…GISTs sometimes show a marked intraor extraluminal growth. 1,2 We present a case in which a marked rotation was clearly observed with real-time ultrasonography (US). A wide range of US fi ndings of GISTs have been reported, but such a gross movement has not been reported in the literature.…”