Cystic echinococcosis, the disease caused by the tapeworm’s larvae, is a zoonotic infection that circulates between animals and humans. Sheep, cattle, and other livestock serve as intermediate hosts, while dogs and other canids carry the adult worms. Humans become accidental hosts when they inadvertently swallow parasite eggs shed in animal feces. Once inside the human body, the eggs hatch into larvae that travel through the bloodstream and most often settle in the liver, where they form fluid-filled cysts that can grow silently for years. The liver accounts for the vast majority of cases, and pancreatic involvement is exceedingly rare, which is precisely what made this patient’s presentation so challenging.

Serologic testing told part of the story. An enzyme-linked immunosorbent assay detected IgG antibodies specific to Echinococcus granulosus, confirming that the patient had been exposed to the parasite. But blood tests alone cannot pinpoint where active cysts are located or whether every cystic lesion on a scan shares the same cause. Ultrasonography, computed tomography, and magnetic resonance imaging were brought to bear on the problem. The scans identified recurrent hepatic cystic echinococcosis lesions that radiologists classified as CE2, CE4, and CE5 on the World Health Organization’s standardized staging system, which grades hydatid cysts from active, fertile stages through transitional forms to inactive, calcified remnants. In the pancreatic body, the imaging revealed a 16-millimeter cystic lesion that did not enhance after contrast administration, a feature that offered no clear clue to its identity.

That tiny pancreatic cyst became the crux of the case. The differential diagnosis for pancreatic cystic lesions is a crowded field, ranging from benign pseudocysts left over from pancreatitis to mucinous neoplasms, intraductal papillary mucinous neoplasms, and pancreatic cancer. Pancreatic echinococcosis sits at the far rare end of the spectrum, so uncommon that many surgeons will never encounter a confirmed case in their careers. With a positive Echinococcus serology already on record, the medical team could not exclude the possibility that the tapeworm had colonized the pancreas. At the same time, the lesion showed none of the characteristic imaging signatures of a hydatid cyst, such as daughter cysts, floating membranes, or a distinctive multilocular appearance, leaving its true nature genuinely indeterminate before surgery.

Facing a giant recurrent lesion in the right lobe of the liver that was closely entangled with the biliary structures, the surgical team elected to perform a right hepatectomy rather than a conservative resection. The reasoning was grounded in operative practicality: removing the entire right lobe eliminated the risk of leaving behind a large residual cavity, a well-known setup for fluid accumulation, infection, and persistent bile leakage. Alongside the liver resection, the surgeons performed a common bile duct exploration and a cholecystectomy to address the biliary involvement. The liver specimen went to pathology, where histopathological examination confirmed the diagnosis of cystic echinococcosis, validating the preoperative workup for the hepatic disease.

The pancreas, however, demanded a more conservative approach. During the operation, the surgeons assessed the pancreatic lesion by direct inspection and palpation. Intraoperative ultrasonography, a technique that could have provided real-time characterization of the cyst’s internal architecture, was not performed. Because the lesion lacked the typical features of hydatid disease, the team deliberately avoided pancreatic resection, sparing the patient from a major operation with significant morbidity. Pancreatic surgery carries substantial risks, including fistula formation, and resecting healthy or benign tissue in pursuit of an uncertain diagnosis is exactly the kind of intervention careful surgeons strive to avoid when the evidence does not compel action.

Follow-up imaging added a cautious note of reassurance but no definitive answers. One month after surgery, a computed tomography scan showed no obvious enlargement of the pancreatic lesion. Yet the report’s authors are explicit that a single month of radiologic stability cannot establish that a cyst is benign. Slow-growing pancreatic neoplasms and indolent parasitic cysts alike can remain quiescent for months or even years before declaring their biological behavior. Because no pathological confirmation of the pancreatic lesion was ever obtained, its exact nature remains unknown, an honest admission that underscores the limits of even thorough imaging-based diagnostics.

The authors of the report outline a roadmap for managing similar cases that hinges on a multi-layered diagnostic strategy. Serum assessment of tumor markers such as carbohydrate antigen 19-9 and carcinoembryonic antigen can help stratify the risk of malignancy in pancreatic cysts. Endoscopic ultrasonography offers a close-up view of the pancreatic parenchyma that conventional cross-sectional imaging cannot match, and when appropriately indicated, endoscopic ultrasonography-guided fine-needle aspiration can obtain fluid and tissue for cytologic and biochemical analysis. In this patient’s case, those steps remain options for the future, paired with the essential commitment to long-term imaging surveillance, since only sustained follow-up will reveal whether the lesion grows, changes character, or quietly persists.

The broader lesson from this case extends well beyond a single hospital ward in Qinghai. Cystic echinococcosis remains endemic across large swaths of Central Asia, western China, the Middle East, South America, and parts of Africa and the Mediterranean basin, placing millions of people at risk and burdening health systems with a disease that often requires complex surgery. In endemic regions, clinicians encountering an indeterminate cyst anywhere in the body must keep echinococcosis in the differential, particularly when the patient carries a known history of hydatid disease. At the same time, the case demonstrates that a positive serologic result in a patient with proven hepatic disease does not automatically explain every coincidental finding, and that resisting reflexive resection of ambiguous lesions, while committing to disciplined follow-up, can spare patients unnecessary operations without compromising safety.

For now, the patient’s pancreatic cyst remains a mystery under watchful observation, a small reminder that in medicine, knowing when not to operate can be as consequential as knowing when to cut. The case report, prepared according to the CARE guidelines and published with the patient’s informed consent, offers clinicians in endemic areas a concrete template for navigating the intersection of a common parasitic disease and a rare diagnostic gray zone, one that combines serology, multi-modal imaging, judicious intraoperative assessment, tumor marker testing, and the patience of long-term surveillance.

Subject of Research: Preoperative differential diagnosis of recurrent hepatic cystic echinococcosis with a concomitant pancreatic cystic lesion

Article Title: Diagnostic dilemma in the preoperative differential diagnosis of recurrent hepatic echinococcosis with a concomitant pancreatic cystic lesion: a case report

Article References: Nie, J., Chen, Y., Du, Y., Zhao, Q., & Wang, Z. (2026). Diagnostic dilemma in the preoperative differential diagnosis of recurrent hepatic echinococcosis with a concomitant pancreatic cystic lesion: a case report. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14515-9

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14515-9

Keywords: cystic echinococcosis, hepatic hydatid disease, pancreatic cystic lesion, Echinococcus granulosus, differential diagnosis, right hepatectomy, endoscopic ultrasonography, computed tomography, serologic testing, long-term imaging surveillance, zoonotic parasitic disease, case report