Ball of wool sign (hydatid cyst)
The ball of wool sign, also referred to as the yarn sign or congealed water lily sign, is an ultrasound appearance, representing degeneration of hydatid cysts (WHO class CE 4). The inner side of cyst detaches from the cyst wall and folds on itself, causing a change from anechoic (fluid) to a solid, hyperechoic appearance without internal septations or daughter cysts 4.
- 1. "Differential Diagnosis in Abdominal Ultrasound." Google Books. N.p., n.d. Web. 25 Nov. 2016.
- 2. Venkatesh, M. "World Health Organization 2001 Classification of Hepatic Hydatid Cysts | Radiology Reference Article | Radiopaedia.org." Radiopaedia Blog RSS. N.p., n.d. Web. 25 Nov. 2016.
- 3. Grisolia, A., G. Troìa, G. Mariani, E. Brunetti, and C. Filice. "A Simple Sonographic Scoring System Combined with Routine Serology Is Useful in Differentiating Parasitic from Non-parasitic Cysts of the Liver." Journal of Ultrasound. Elsevier, June 2009. Web. 25 Nov. 2016.
- 4. Ilter T, Ozgüven O, Mentes NK. "Ball of wool" or "yarn" sign: a new ultrasonographic sign for the diagnosis of hydatid cysts. A preliminary report. The British journal of radiology. 58 (695): 1141. Pubmed