Soft Tissue Lipoma

A longitudinal ultrasound image of the back (behind the scapula) shows a well-circumscribed, oval, solid mass (arrows) with internal slight hyperechogenicity superficial to the deep muscle.

Facts: Soft Tissue Lipoma

• Very common mesenchymal tumors
  
• May be palpable, painless, soft and mobile on clinical examination
  
• May be multiple in up to 5% of cases
• Common in patients older than 50 years

US Findings

• Classic lipomas are hyperechoic and homogeneous (compared with muscle) with well-defined borders
• Sonographic appearance may depend on internal cellularity (amount of fat and water in the lesion). Lesions with pure fat are hypo- or anechoic but those with mixed fat/water are quite echogenic
• Appearance highly variable from hyper-, iso-, hypoechoic or mixed echoic and bordes can be circumscribed or poorly defined
  
• It can be difficult to confidently diagnose lipoma on US, accounting for variable US features and high interobserver variability on description of lesions.
  

Our case: soft tissue lipoma proven by histopathology

Reference:

Inampudi P, Jacobson JA, Fessell DP, et al. Soft-tissue lipomas: accuracy of sonography in diagnosis with pathologic correlation. Radiology 2004;233:763-767.

Hepatic Hemangioma: MR Findings

Axial MR images show a large left hepatic lobe mass that has a very high T2 signal intensity and peripheral nodular contrast enhancement and incomplete delayed fill-in.

Facts:

• Most common benign hepatic tumor
• Female:male ratio = 2:1 to 5:1
• Most are asymptomatic and found incidentally on imaging exams
• US, CT, MRI and nuclear medicine scan may demonstrate hemangioma
• Routine MR protocol for characterizing liver lesions = T1, FSE T2 (with fat suppression), dynamic gadolinium enhancement

MR Imaging Findings

• A mass with T1 hypointensity, strong T2 hyperintensity with a "light bulb" pattern on heavily T2W sequence
• Dynamic enhancement shows peripheral nodular enhancement (the nodules do not contact each other) with progressive centripetal enhancement. The inner ring of the enhancement is undulating.
• Washout phase: persistent homogeneous enhancement without heterogeneous or peripheral washout
• Small lesions may demonstrate homogeneous arterial enhancement but the enhancement will be persistent and homogeneous in washout phase.

Reference:

Lencioni R, Cioni D, Iartolozzi C. Focal liver lesions: detection, characterization, ablation. 2005

Intestinal Ascariasis

Author: Santip Srisuwan, M.D.

Axial CT image shows multiple tubular filling defects (arrows) within the opacified lumen of the small bowel. Note contrast filling within the filling defects.

Facts:

• Most common helminthic infection (worldwide prevalence 25%)
• Usually asymptomatic.
• Possible symptoms are colicky abdominal pain in adults and growth retardation/intussusception/volvulus in children

Imaging

• X-ray: usually normal but may present as bowel obstruction (partial or complete), or soft tissue masses
• US: hypo echoic curvilinear tubular structures with well-defined echogenic walls and curling movement of the worm during the exam
• CT: long, thin tubular structure coiled within the small bowel, outlined by oral contrast materials

References:

1. Hommeyer SC, Hamill GS, Johnson JA. CT diagnosis of intestinal ascariosis. Abdom Imaging 1995;20:315-316.

2. Rodrigues EJ, Gama MA, Ornstein SM, et al. Ascariasis causing small bowel volvulus. Radiographics 2003;23:1291-3.

3. Villamizar E, Mendez M, Bonilla E, et al. Ascaris lumbricoides infestation as a cause of intestinal obstruction in children: experience with 87 cases. J Pediatr Surg 1996;3:201-4.

4. Hendi JM, Horton KM, Fishman EK. Ascariasis infection of the colon: MDCT evaluation. Emerg Radiol 2006;12:180-1.

5. Bude RO, Bowerman RA. Case 20: Biliary ascariasis. Radiology 2000;214:844-7.

6. Hershkovitz D, Wasserberg N. Large bowel obstruction due to Ascaris lumbricoides. IMAJ 2004;6:115-116.