Water lily sign (hydatid cyst)

Last revised by Rohit Sharma ◉ on 5 Dec 2024

Citation, DOI, disclosures and article data

Citation:

Gaillard F, Sharma R, Kearns C, et al. Water lily sign (hydatid cyst). Reference article, Radiopaedia.org (Accessed on 28 Mar 2025) https://doi.org/10.53347/rID-2281

DOI:

https://doi.org/10.53347/rID-2281

Permalink:

https://radiopaedia.org/articles/2281?embed_domain=external.radpair.com%2527%255B0%255D%2527%255B0%255D

rID:

2281

Article created:

2 May 2008, Frank Gaillard ◉ ◈

Disclosures:

At the time the article was created Frank Gaillard had no recorded disclosures.

View Frank Gaillard's current disclosures

Last revised:

5 Dec 2024, Rohit Sharma ◉

Disclosures:

At the time the article was last revised Rohit Sharma had no financial relationships to ineligible companies to disclose.

View Rohit Sharma's current disclosures

Revisions:

32 times, by 23 contributors - see full revision history and disclosures

Systems:

Chest, Hepatobiliary, Musculoskeletal

Sections:

Signs

Tags:

lung

Synonyms:

Water lilly sign
Camalote sign
Waterlily sign
Water-lilly sign
Water lily

The water lily sign, also known as the camalote sign, is seen in hydatid infections when the inner endocyst detaches from the outer pericyst, resulting in a free-floating membrane within the cyst.

It is classically described on plain radiographs (mainly chest x-ray) when the collapsed membranes are calcified, but may be seen on ultrasound, CT, and MRI.

History and etymology

The water lily sign is termed for its resemblance to a water lily pad floating on water ⁵. Similarly, camalote is another name for the water hyacinth, a free-floating aquatic plant ⁶.