Gastrointestinal stromal tumors: ultrasonographic spectrum of the disease.

Objective: The purpose of this series was to determine the spectrum of findings on gray scale trans-abdominal ultrasonography (TAUS) in pathologically proven cases of primary gastrointestinal stromal tumors (GISTs) and correlate them with gross morphologic and pathologic findings.

Methods: The series included 18 patients with a primary GIST tumor detected on preoperative TAUS. The ultrasonographic findings were evaluated for features such as tumor size, shape, margin, echogenicity, and presence of fluid components, and the features were compared with morphologic and pathologic findings.

Results: All of the primary GISTs were hypoechoic extraluminal masses with well-delineated margins. Eight GISTs were homogeneously solid masses, and 8 were heterogeneously solid masses that contained a large central area of lower echogenicity (n = 4) or multiple internal hypoechoic irregular spaces (n = 4) corresponding to necrosis and hemorrhage. Other tumors had a cystic appearance (n = 1) or showed a dual hyperechoic-hypoechoic echo structure (n = 1). Three tumors showed intratumoral gas due to fistulization into the bowel lumen, which appeared as hyperechoic foci or a linear hyperechoic area with acoustic shadowing. The heterogeneous tumors were significantly larger (P = .03) and had higher mitotic counts (P = .05). Gastrointestinal stromal tumors with high malignant potential tended to be large and showed intratumoral heterogenicity with areas of lower echogenicity.

Conclusions: Gastrointestinal stromal tumors showed varied patterns on TAUS. The ultrasonographic pattern depended on the tumor size and mitotic activity. Ultrasonographic features suggesting high malignant potential were size and internal heterogenicity with the presence of intratumoral hypoechoic areas.