Comet Sign

com·et tail sign

in chest radiology, the curved appearance of pulmonary arteries and veins associated with rounded atelectasis, fibrosis associated with organizing pleurisy.
Synonym(s): comet sign
Imaging Blood vessels Comet tail sign A term referring to the CT appearance of a tapering, noncalcified vein, adjacent to a rounded phlebolith, which serves to differentiate it from a stone in the ureter
Imaging Gallbladder A term referring to reverberation artifacts seen by ultrasonography within a thickened wall of the gallbladder, strongly suggesting small cholesterol crystals within Rokitansky-Aschoff sinuses in adenomyomatosis, which is usually asymptomatic. Air in emphysematous cholecystitis may produce a similar picture, but in contrast to patients with cholesterol crystals, those with emphysematous cholecystitis are clinically unwell
Imaging Lung Parachute sign A focal area of collapsed lung adjacent to pleural thickening with distortion of blood vessels, which is seen as a curvilinear soft tissue density on a plain chest film, which extends from the lateral pleura to the hilum (this image is more parachute-like, given the multiple ‘tails’); the sign is due to contracted fibrous scarring and shrinking pleuritis with rounded atelectasis, and seen in the folded lung syndrome
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References in periodicals archive ?
published an interesting article (1) about dermatitis in France caused by Pyemotes ventricosus in which they highlight the presence of the comet sign in a number of their patients.
In 2 patients (Figure, panels A and B), the comet sign can be clearly assessed; the patients were 2 women who had had direct contact with the infected material against their legs.
Perhaps both signs may characteristic this dermatitis: the comet sign and "the sign of the infected investigators" of the outbreaks.
Patients affected had highly erythematous pruritic macules typical of arthropod bites, sometimes associated with a linear erythematous macular tract that we called the comet sign (Figure 1).
From May through September 2007, all patients referred to the dermatology department at Frejus Hospital (Frejus, France) with suspected arthropod-bite dermatitis were examined; patients were also checked for the comet sign.
Whenever possible, ecoenvironments (surrounding terrain and home interior) of patients with typical macules associated with the comet sign were investigated.
Twenty-four hours later, an erythematous macular pruritic lesion was observed that lasted for 7 days, but no comet sign developed.
Typical lesions with the comet sign (Figure 1, panels E and F) developed in these investigators after they touched wood dust and infested furniture (1 of the investigators had only entered a room with infested furniture but had not touched it).
In 2006, we described an outbreak of an unusual dermatitis associated with a specific clinical sign that we called the comet sign (1).
Natural infestation gave rise to macules frequently associated with the comet sign.