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CT in pulmonary hydatid disease: unusual appearances
1Departments of Internal Medicine, SheriKashmir Institute of Medical Sciences, Srinagar, Kashmir, India. parvaizk@hotmail.com
Objective:
To study the CT features of pulmonary hydatid disease.
Patients:
Thirty-two consecutive patients with surgically proven pulmonary hydatid cysts.
Setting:
SheriKashmir Institute of Medical Sciences, Srinagar, Kashmir, India, a tertiary-care referral center.
Interventions:
CT of the chest was obtained in all cases on Somatom DR double rotate CT scanner (Siemens; Erlangen, Germany).
Results:
Forty cysts of different size and shapes were encountered, 34 of them being ruptured. CT density of the cysts varied from - 42 to 160 Hounsfield units (HU; median, 15.5 HU). Apart from the classically described features of pulmonary hydatid disease, a crescent-shaped rim of air at the lower end of the cyst (inverse crescent sign) was seen in three cysts, and a bleb of air in the wall of two as-yet unruptured cysts (signet ring sign). Thick wall (>10 mm) was observed in four cysts, and each of them had associated evidence of infection.
Conclusions:
Inverse crescent sign, signet ring sign, high CT density, and thick wall should be recognized as features of pulmonary hydatid cysts on CT.