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Phrygian caps are the most common congenital anatomic variant of the gallbladder. It denotes folding of the fundus back upon the gallbladder body and is asymptomatic with no pathological significance.
A Phrygian cap may be identified on ultrasound, multiphase CT/MRI, or cholescintigraphy 3.
May be wrongly interpreted as a septum in an otherwise normal gallbladder.
Multiphase CT/MRI usually clearly differentiates Phrygian caps from mass lesions.
When multiphase CT/MRI is inconclusive, cholescintigraphy may be critical in preventing an unnecessary cholecystectomy. The gallbladder often appears smaller than the gallbladder fossa. Delayed imaging demonstrates filling of the gallbladder, which rules out an underlying mass lesion.
Treatment and prognosis
As a benign anatomical variant, Phrygian caps should not be mistaken for a pathology and does not require treatment.
History and etymology
- 1. Meilstrup J, Hopper K, Thieme G. Imaging of Gallbladder Variants. AJR Am J Roentgenol. 1991;157(6):1205-8. doi:10.2214/ajr.157.6.1950867
- 2. Boyden EA. The phrygian cap in cholecystography: a congenital anomaly of the gallbladder. Am J Radiol 1935;33:589.
- 3. van Kamp M, Bouman D, Steenvoorde P, Klaase J. A Phrygian Cap. Case Rep Gastroenterol. 2013;7(2):347-51. doi:10.1159/000354789