DOI: 10.6084/m9.figshare.31155178.v1
title: Supplementary Material for: Echinococcosis, a challenging treatment

description: We report the case of a 38-year-old man from Uzbekistan, living in Portugal for eight years and without relevant medical history, referred to Gastroenterology after liver nodules were detected during evaluation of intermittent right upper abdominal pain. Ultrasound revealed two heterogeneous, predominantly hyperechogenic cystic lesions in segments VII and VIII, showing the “ball of wool” sign, consistent with inactive hydatid cysts (WHO stage 4) (Fig. 1). A third 53-mm cyst in segment V exhibited detached membranes and septations, compatible with a transitional hydatid cyst (WHO stage 3a) (Fig. 2). Magnetic resonance cholangiography confirmed these findings and showed compression of the peripheral biliary tract with biliary ectasia. Laboratory tests revealed normal liver function, and serology for Echinococcus granulosus was negative. Combined therapy with albendazole and PAIR (Puncture-Aspiration-Injection-Reaspiration) was proposed. Under ultrasound guidance, the stage 3a cyst was punctured, yielding 15 cc of clear fluid, followed by instillation of 10 cc of 96% alcohol (Fig. 3). After 30 minutes, the cyst was punctured again and fully drained. The procedure was uneventful, as confirmed by post-procedure CT (Fig. 4). Albendazole 400 mg daily was started three days before PAIR and continued for three months.
Hydatid disease, or echinococcosis, is a zoonosis generally caused by Echinococcus granulosus, which can affect several organs, mainly the liver [1-3]. Clinical manifestations depend on the organ involved and cyst viability [2, 3]. The diagnosis relies on serology and imaging studies [2]. The serology of Echinococcus granulosus is positive in 70% of cases [2, 3]. The encystment of the metacestode can prevent the stimulation of antibody-producing cells, leading to undetectable antibody levels against Echinococcus spp. antigens, which can explain many negative results [2]. The WHO classification system contains six categories, based on cyst imaging features [2, 3]. The cystic echinococcosis (CE) stages 1 and 2 correspond to active stages: CE1 as a uniform anechoic cyst with internal echoes and CE2 as a multivesicular “honeycomb” [2]. Stage 3 is a transitional stage: CE3a is a unilocular cyst with detached laminated membranes and CE3b has daughter cysts within a solid matrix [2]. The CE stages 4 and 5 are inactive and degenerative cysts with a hypoechoic and hyperechoic signal, the “ball of wool” sign [2]. Treatment of active cysts is indicated, based on mebendazole or albendazole associated with surgical resection or percutaneous treatment, known as PAIR, mainly in cysts with more than 50 mm of diameter [1, 2]. It is agreed that these agents should be administered before the procedure and continued postoperative, generally for 3-6 months after to avoid contamination [2]. Study protocols vary widely, with reported initiation periods ranging from 1 to 15 days; however, most studies advocate starting treatment approximately 2 weeks beforehand to reduce cyst viability [4, 5].
We highlight the need to recognize the imaging features of the different stages of echinococcosis—an uncommon cause of hepatic cystic lesions in Western Europe, including Portugal. This case typifies a rare disease in our region and serves as an educational example to illustrate its management and current therapeutic considerations.