CT in pulmonary hydatid disease: unusual appearances

Chest. 2000 Dec;118(6):1645-7. doi: 10.1378/chest.118.6.1645.


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.

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Echinococcosis, Pulmonary / diagnostic imaging*
  • Female
  • Humans
  • Lung / diagnostic imaging*
  • Male
  • Middle Aged
  • Tomography, X-Ray Computed*