Imaging in pulmonary hydatid cysts

Table 1 Classical signs of pulmonary hydatid cyst on chest X-ray

Uncomplicated hydatid cyst	Complicated hydatid cyst
Well circumscribed round radio-opacity (resembling canon ball on AP and rugby ball on lateral projection)	Crescent sign
Polycyclic and bilobed appearance	Cumbo or double arch sign
Slot sign (impending rupture)	Water lily or camelotte sign
	Rising sun sign
	Dry cyst sign

AP: Anteroposterior.

Table 2 Computed tomography signs described in pulmonary hydatid cyst

Signs of contained rupture

Crescent sign

Inverse crescent sign

Signet ring sign1

Air bubble sign2

Signs of cyst rupture

Cumbo sign

Serpent sign

Swirl sign

Water lily sign

Mass within a cavity sign

Incarcerated membranes sign

Dry cyst sign

Signs of cyst infection

Air bubble sign2

Ring enhancement sign

Air fluid level

¹Indicated impending rupture;

²can be seen in contained rupture as well as superadded infection.