Bronchoscopic Visualization of Hydatid Cyst Membrane

A 45-year-old nonsmoker woman from a rural area presented with complaints of cough and right-sided chest discomfort for 3 months. She denied any history of fever, dyspnea, hemoptysis, or weight loss. Her chest radiography revealed a cavity with an air–fluid level in the right lower zone. Microbiological analysis of sputum did not find any pathogenic organisms. Computed tomography of the thorax showed a cavitating lesion with an air–fluid level in the right lower lobe of the lung. An undulating membranous structure was seen floating at the air–fluid interface. This characteristic appearance is known as the water lily sign or camalote sign [Figure 1a]. Flexible bronchoscopy revealed a glistening white membranous structure protruding through the medial basal segmental bronchus of the right lower lobe [Figure 1b]. A small fragment of the membrane was retrieved using a biopsy forceps. Histopathological examination of the fragment showed an acellular laminated membrane [Figure 1c]. Immunoglobulin G antibodies against Echinococcus were positive. A diagnosis of a ruptured hydatid cyst was made. She was started on albendazole therapy and is awaiting surgical removal.Figure 1: (a) An axial image of computed tomography of the thorax showing a cavity with an air-fluid level in the right lower lobe of the lung. There is also the presence of a wavy membrane floating at the interface. (b) A flexible bronchoscopic image showing a glistening white membrane protruding out through the medial basal segmental bronchus of the right lower lobe. (c) Histopathological examination of a biopsy specimen (H&E stain, 10×) showing an acellular laminated membrane.Pulmonary hydatid disease, caused by Echinococcus granulosus, usually presents as a well-defined cystic lesion on radiology. However, the cyst may rupture in up to 47% of cases, producing several distinctive imaging signs. Following rupture, the endocyst may become completely detached and float like a wavy membrane in the remaining fluid inside.[1] In complete rupture, the cyst may communicate with the bronchial tree or pleural cavity. Expectoration of hydatid fluid and membrane fragments indicates rupture into the bronchial system. This is uncommon but is a pathognomonic feature of pulmonary hydatid cyst. Bronchoscopic demonstration of a shiny white gelatinous cyst membrane is a specific finding.[2,3] Protrusion of the white germinative membrane into the bronchial tree confirms a cystobronchial communication and supports the diagnosis without ambiguity.