ARRS Case of the Week- Sep 25, 2017

ULTRASOUND: Abdomen

Case Author: Ulrike M. Hamper, MD, MBA, Johns Hopkins University

History

56-year-old man with incidental finding of pelvic mass on a CT scan obtained after a motor vehicle accident and history of craniotomy for anaplastic astrocytoma.

Imaging Findings

Sagittal (A) and transverse (B) ultrasound images of the pelvis show a 9.7 × 5.6 cm heterogeneous solid mass with internal necrosis (fluid-debris level in B) posterior to the urinary bladder (B). Color (C) and power (D) Doppler images show the mass is highly vascular with evident arterial flow.

Gastrointestinal stromal tumor
Lymphoma
Metastasis
Sigmoid diverticulitis with abscess

Diagnosis

Gastrointestinal stromal tumor

Teaching Points

Gastrointestinal stromal tumor (GIST) is a rare neoplasm thought to originate from mesenchymal cells (smooth-muscle origin) of the GI tract. They occur most commonly in the stomach (70%) and small bowel (20%) and less frequently in the esophagus (10%) and rectum. Small GISTs appear as intraluminal masses; larger tumors (> 5 cm) grow outward from the bowel. Sonographically, smoothmuscle tumors appear as round masses of varying echogenicity, often with cystic central change due to hemorrhage or necrosis. Primary lymphoma constitutes 2–4% of all GI tract malignancies but accounts for 20% of those found in small bowel. The GI tract may also be diffusely involved through widespread dissemination in advanced stages of lymphoma of any cell type. Growth patterns observed at sonography may be nodular or polypoid masses, carcinomalike ulcerative lesions, and infiltrating tumor masses. Malignant melanoma and lung and breast cancer are the most common tumors to metastasize to the GI tract. The stomach, small bowel, and colon, in decreasing order of frequency, are most commonly involved. Plaques of soft tissue can be deposited on the surface of small or large bowel or as peritoneal drop metastatic lesions or omental cake engulfing the involved bowel loops. The presence of ascites, omental thickening, visceral and parietal peritoneal nodules, plaques, or a combination of these abnormalities suggests metastatic spread. Diverticulitis results from microscopic or macroscopic perforation of diverticula and can result in perforation with abscess formation. Classic sonographic features include segmental thickening of the gut, inflamed diverticula containing air, and inflamed perienteric fat. When diverticulitis is complicated by perforation or abscess formation, an extraluminal collection of gas or fluid may be seen.

Schedules and Media