M Amin, A Tahir, M Shafique
endocyst, hydatid cyst, membrane, rupture, sonogram
M Amin, A Tahir, M Shafique. Images in Sonography: Detached Membrane Sign. The Internet Journal of Radiology. 2006 Volume 5 Number 2.
A case of hepatic hydatid cyst is presented in which one monthly follow up of ultrasound of a hydatid cyst revealed an undulating membranous structure with disappearance of the inner membrane as seen on first sonogram. A diagnosis of hydatid cyst was given and confirmed by surgery
A 26 year old male patient presented with pain in right hypochondrium for 7 months. An ultrasound performed revealed a well defined cystic structure with an inner membrane (Figure 1-arrows).
An impression of hydatid cyst was given. The patient was offered surgical treatment at this time to which he denied. A follow up ultrasound done one month latter revealed a wavy band of delaminated membrane within the cyst (Figure 2-arrows). The outer membrane seen on first scan had disappeared. The patient was referred for surgery. The resected cystic structure (Figure 3) was identified as a hydatid cyst on pathological exanimation.
Hydatid disease is a worldwide zoonosis produced by the larval stage of the Echinococcus tapeworm. It consists of an outer membrane ectocyst, middle layer pericyst and an inner laminated membrane the endocyst. Detachment of the laminated membrane (endocyst) from the pericyst can be visualized as undulating membrane within the cyst. This sign was seen in our case. Detachment of the endocyst from the pericyst is probably related to decreasing intracystic pressure, degeneration, host response, trauma, or response to therapy1. Endocyst detachment is seen at ultrasound as floating membranes within the cyst.