Ball of wool sign (hydatid cyst)

Last revised by Ayla Al Kabbani on 1 Feb 2020

Citation, DOI, disclosures and article data

Citation:

Khader.O.Thabet M, Al Kabbani A, Knipe H, et al. Ball of wool sign (hydatid cyst). Reference article, Radiopaedia.org (Accessed on 02 Dec 2023) https://doi.org/10.53347/rID-49542

DOI:

https://doi.org/10.53347/rID-49542

Permalink:

https://radiopaedia.org/articles/49542

rID:

49542

Article created:

28 Nov 2016, Mohammed Al Khader.O.Thabet

Disclosures:

At the time the article was created Mohammed Al Khader.O.Thabet had no recorded disclosures.

View Mohammed Al Khader.O.Thabet's current disclosures

Last revised:

1 Feb 2020, Ayla Al Kabbani ◉

Disclosures:

At the time the article was last revised Ayla Al Kabbani had no recorded disclosures.

View Ayla Al Kabbani's current disclosures

Revisions:

8 times, by 7 contributors - see full revision history and disclosures

Systems:

Chest, Gastrointestinal

Sections:

Signs

Tags:

hydatid disease, cases

Synonyms:

Spin sign
Whorl sign
Congealed water lily sign
Yarn sign

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 the 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.