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Indian Pediatrics 1999;36: 949-952 |
Serial Sonographic Changes in Hydatid Cyst Following Medical Therapy |
A six-year-old girl presented in 1991, with abdominal pain and loss of appetite of three months duration. Physical examination revealed hepatomegaly three fingers below the costal margin. Ultrasound examination at that time, showed a hydatid cyst in the right hepatic lobe (Fig. 1). Serological tests con firmed the diagnosis of hydatid cysts. Medical therapy with albendazole was then instituted for a period of 3 months. She remained well and reported for follow up in 1992 and the ultrasound then revealed a "floating water lilly sign" (Fig. 2). The patient conti-nued to be asymptomatic and was kept under close follow up for the next six years. The ultrasound scans revealed a congealed water lilly sign (Fig. 3) in 1998 and a few areas of echogenic foci (Fig. 4) in 1999.
Fig. 1. Hypoechoic area (labelled as cyst) seen in right hepatic lobe.
Fig. 2. Hepatic sonogram one year after albendazole therapy shows echogenic area with linear membrane on either side (arrows) simulating a floating water lilly seen within the cyst.
Fig. 3. Sonogram 7 years after albendazole therapy shows multiple closely folded echogenic membranes (arrows) in the cyst; the "congealed water lilly sign".
Fig. 4. Sonogram 8 years after medical therapy shows scattered echogenic foci in the cyst (marked with arrows). The ultrasound signs of hydatid cyst are well known, but the sonographic changes following medical therapy have been described only recently(1). These authors sonographically followed up patients treated with mebendazole/albendazole for a period upto 8 years. These authors believe that following albendazole/mebendazole therapy, there is a loss of intra cystic pressure, and the germinal layer falls away from the pericyst giving rise to a "floating water lilly" sign, from a simple cyst. With further treatment, the cysts become smaller and the germinal layer is more closely packed and appears like multiple curvilinear structures. Simulateno-usly the intervening matrix becomes more echogenic. These membranes do not move with change of patient's posture. This is the "congealed water lilly" sign. With further degeneration of the parasite, only a few echogenic foci are seen within the "congealed water lilly". Finally, after complete degeneration, only focal areas of germinal matrix remain and appear as echogenic foci. It is further postulated by these authors, that these changes are highly suggestive of a dead or inactive parasite. These sonographic appearances of folded membranes in a treated hydatid cyst have been named as "ball of wool" sign, "yarn sign" or "spin/whirl" sign by other workers, but these authors did not comment on the activity of the parasite when such a sign was seen(2,3). Differential diagnosis of congealed water lilly sign in the liver includes liver abscess and solid liver tumors. Although clinical correlation and serological data are always essential to rule out these possibilities, an experienced sonologist usually faces no difficulty in differentiating these entities. Shabnam Bhandari Grover, References 1. Sabih DE, Sabih Z, Khan AN. Congealed water lilly sign: A new sonographic sign of liver hydatid cyst. J Clin Ultrasound 1996; 24: 297-303. 2. Ilter T, Ozguven O, Mentes NK. Ball of Wool or Yarn Sign: A new ultrasonic sign for the diagnosis of hydatid cysts. A Preliminary Report. Brit J Radiol 1985; 58: 1141. 3. von Sinner WN. New diagnostic signs in hydatid disease: Radiography, ultrasound, CT and MRI correlated to pathology. Eur J Radiol 1991; 12: 150-159. |
