How should clinicians diagnose cystic echinococcosis (CE), and what is the best management strategy?

At the Francophone Days of Hepatology, Gastroenterology, and Digestive Oncology 2026, held in Paris, Solange Bresson-Hadni, MD, professor and physician from the National Reference Center for Echinococcoses, Department of Parasitology-Mycology, University Hospital Besançon, in Besançon, France, addressed these questions during a session.

CE is a larval cestode infection that primarily affects the liver and accounts for 70% of all cases. Although uncommon in France, it remains prevalent in other regions, particularly among individuals from the Maghreb, Turkey, and the Balkans.

“The cyst comprises two components: the parasite (hydatid) and the adventitial layer, which is a fibroinflammatory host reaction that may calcify. The parasite is a fluid-filled structure under pressure, with an inner germinal layer and an outer laminated layer that protects against immune defenses,” Bresson-Hadni said.

In France, CE is often identified incidentally during imaging for unrelated indications. Symptomatic presentation includes pain or complications, such as rupture into the biliary tract, which may result in immune-allergic manifestations and parasitic dissemination.

Diagnostic Approach

Diagnosis relies primarily on ultrasound, with MRI used as a complementary modality. The World Health Organization (WHO) distinguishes six stages (CE1 to CE5) that reflect parasite activity: active stages (CE1 and CE2), transitional stages (CE3a and CE3b), and inactive stages (CE4 and CE5). Ultrasound enables differentiation between hydatid and biliary cysts by identifying the characteristic double wall, whereas the presence of intracystic fluid shows ongoing parasitic activity.

“MRI is useful for defining cyst contents, particularly with T2-weighted sequences, and for detecting any occult biliary communication,” Bresson-Hadni added.

Serologic Testing

“First line screening relies on a combination of indirect hemagglutination, and enzyme linked immunosorbent assay, with a cumulative sensitivity of about 80% for CE with hepatic involvement,” Bresson-Hadni said. “Western blot is used as a second step and remains the most sensitive and specific test, particularly when first line results are negative despite suggestive imaging findings.”

She noted that negative serologic results did not exclude the diagnosis of CE.

Management Strategies

Management is multidisciplinary and follows the updated WHO recommendations released in late 2025.

• Albendazole is a parasitostatic agent administered continuously at 10-15 mg/kg/d, with monitoring for hepatic and hematologic toxicity. It is used as a primary therapy for small active cysts and as an adjunctive therapy with surgery or percutaneous intervention. Contraception is required in women of childbearing age.
• Surgical management prioritizes total cystectomy without opening the cyst. Operative protection involves the use of hypertonic saline solutions. Adjunctive albendazole is administered 1-4 weeks before surgery and for 1 month after surgery for closed cysts or for 3 months if the cyst is opened.
• Percutaneous treatment: This involves Puncture, Aspiration, Injection of scolicidal agent (90% alcohol), and Re-aspiration (PAIR). It is contraindicated in the cases of biliary fistula. Albendazole is initiated 1 week before the procedure and continued for 1-3 months thereafter. Ultrasound monitoring is required for 5 years.
• Simple monitoring is recommended for inactive cysts (CE4 and CE5), with annual ultrasound follow-up for 5 years.

Treatment Algorithm

“I have summarized this in a care algorithm based on the most recent recommendations,” Bresson-Hadni said:

• Inactive cysts: Managed with simple monitoring.
• Small active cysts (< 5 cm): Treated with albendazole.
• Larger active cysts (CE1 and CE3a): Managed with PAIR, with precautions in cases of biliary fistula.
• Large CE3b cysts typically require surgery.
• Complicated forms in cases of rupture or fissuring require surgery, often involving partial hepatectomy. Endoscopic biliary treatment may be sufficient if the cystic material is completely removed; otherwise, surgery is needed as a second step.

This story was translated from Univadis France, part of the Medscape Professional Network.