Solitary fibrous tumors of the soft tissues: review of the imaging and clinical features with histopathologic correlation.

OBJECTIVE: Solitary fibrous tumors are rare soft-tissue tumors of submesothelial origin with variable malignant potential. Most of these tumors originate within the thoracic cavity, but they can occur in a variety of sites, including the abdomen, pelvis, and soft tissues and muscles. The purpose of this study was to review the imaging findings with clinicopathologic correlation in 34 cases. CONCLUSION: The finding of a large, solid, vascular tumor, particularly with prominent feeding vessels or a visible fatty component, should alert the radiologist to the possible diagnosis of solitary fibrous tumor. Percutaneous biopsy carries minimal risk and should be used for definitive diagnosis of these lesions, which in many cases are curable with surgery. The prognosis is good for patients with benign tumors but variable for those with malignant tumors.

Adult rhabdomyosarcoma: cross-sectional imaging findings including histopathologic correlation.

OBJECTIVE: The purpose of our study was to present the MRI and CT features of adult rhabdomyosarcomas with histopathologic correlation. Forty-nine sequential cases were incorporated over a 5-year period from the sarcoma unit database. Twenty-six patients had adequate imaging (16 MRI, 10 CT) and histopathology available for retrospective review. The alveolar subtype was present in 13 patients, embryonal subtype in four patients, and pleomorphic subtype in nine patients. On both CT and T1-weighted MRI, all tumors were isodense to skeletal muscle, although enhancement was variable after the administration of IV contrast material. Pleomorphic tumors were very high signal on T2-weighted/STIR imaging, and both pleomorphic and alveolar subtypes were extremely heterogeneous. Embryonal tumors were more homogeneous. CONCLUSION: Although adult rhabdomyosarcomas have certain imaging appearances in common with other soft-tissue sarcomas, features at presentation such as tumor heterogeneity, site, regional lymphadenopathy, and pulmonary metastasis should make the radiologist consider this important diagnosis.

Malignant gastrointestinal stromal tumor: distribution, imaging features, and pattern of metastatic spread.

PURPOSE: To investigate and describe the anatomic distribution, imaging features, and pattern of metastatic spread of malignant gastrointestinal stromal tumors (GISTs). MATERIALS AND METHODS: The medical records of all patients at our institution with a histologic diagnosis of GIST were reviewed. Two radiologists with knowledge of the diagnosis reviewed the radiologic findings by means of consensus. Sixty-seven patients underwent computed tomography, and scans of the primary tumor were available in 38 patients. RESULTS: One hundred sixteen patients with malignant GISTs were identified (76 men and 40 women; mean age, 54.6 years +/- 13.5 [SD]). The primary tumor locations in descending order of frequency were the small bowel (n = 49), stomach (n = 43), colon (n = 7), rectum (n = 6), other (n = 3), and not specified (n = 8). Mean primary tumor size was 13 cm +/- 6. Tumors were typically well defined (31 of 36 [86%]), with a heterogeneous rim of soft tissue with lower signal intensity than that of the contrast material-enhanced liver. Central fluid attenuation was seen in 24 of 36 (67%) patients. Metastases were seen in 23 of 38 (61%) patients at presentation and in 53 of 61 (87%) patients during follow-up. Spread was usually to the liver or peritoneum. Visceral obstruction rarely occurred, even in the presence of extensive peritoneal metastatic disease. Ascites was an unusual finding. CONCLUSION: Malignant GISTs are typically large, well-circumscribed, heterogeneous, centrally necrotic tumors that arise in the wall of the small bowel or stomach. They rarely obstruct viscera, despite their large size and propensity to metastasize to the liver and peritoneum.