Locally Aggressive Hepatic Echinococcosis With Colonic Involvement Requiring a Right Hemicolectomy: A Case Report and Focused Literature Review

Abstract

Echinococcosis most commonly presents as a slowly enlarging hepatic cyst, whereas extensive inflammatory extension with colonic involvement is uncommon. We report the case of an 80-year-old man who presented with abdominal pain and fever and reported having been aware of a hepatic echinococcal cyst for approximately 30 years. CT showed a giant calcified hepatic cyst containing an air-fluid level and intralesional gas, suggestive of secondary infection; intraoperative cyst-fluid culture subsequently grew Escherichia coli. Emergency laparotomy revealed dense inflammatory adherence to the transverse mesocolon and colon with obliteration of the dissection planes, necessitating right hemicolectomy with ileotransverse anastomosis, partial cyst wall excision, and drainage. Histopathology confirmed echinococcosis with extensive fibrosis, abscess formation, necrosis, and intestinal-surface involvement. The morphology raised suspicion for alveolar echinococcosis, although species-level confirmation was unavailable. The patient recovered uneventfully and received albendazole. This case highlights that chronically infected hepatic echinococcosis may mimic locally invasive disease and require adjacent-organ resection even without a demonstrable cystocolonic fistula.

Introduction

Echinococcosis is a zoonotic parasitic disease caused by the larval stages of cestodes of the genus Echinococcus. Cystic echinococcosis, most commonly caused by Echinococcus granulosus sensu lato, is the predominant human form and remains endemic in livestock-raising regions, including the Mediterranean basin [1-4]. The liver is the most frequently affected organ. Hepatic cystic echinococcosis typically follows a slow, expansile course and may remain clinically silent for years or decades [1-4].

Symptoms and operative complexity are largely determined by cyst size, anatomical location, and complications. Secondary bacterial infection, rupture, biliary communication, and fistulization into adjacent hollow viscera can substantially alter the clinical and radiological appearance [2,4-6]. On CT, intracystic gas or an air-fluid level should raise concern for infection or communication with the biliary or gastrointestinal tract, particularly in a chronically calcified lesion [5,6].

Alveolar echinococcosis, caused by Echinococcus multilocularis, differs biologically from cystic echinococcosis. It is characterized by multivesicular, infiltrative growth and may resemble a locally invasive hepatic malignancy [2,7,8]. Nevertheless, severe inflammation, abscess formation, fibrosis, and rupture in long-standing cystic echinococcosis may also create an aggressive operative phenotype. Distinguishing the two entities can therefore be difficult when only conventional histology and nonspecific serology are available [9,10]. In the present case, suspicion for alveolar echinococcosis was raised by the presence of a separate retroperitoneal lesion, extrahepatic involvement, and laminated membrane fragments embedded within dense fibrous adhesions on the intestinal surface. Conversely, the 30-year history of a giant, heavily calcified hepatic cyst with intralesional gas and abscess formation was also compatible with severely complicated cystic echinococcosis. Therefore, in the absence of species-specific PCR or Em2G11 immunohistochemistry, alveolar echinococcosis remained suspected rather than confirmed.

Colonic involvement is particularly uncommon. A 2019 systematic review identified only nine published cases in which hydatid disease directly affected the colon or produced a clinically relevant colonic complication [11]. We present a long-standing hepatic echinococcal lesion complicated by infection, extensive extrahepatic inflammatory adhesions, and colonic involvement requiring right hemicolectomy in the absence of a documented cystocolonic fistula.

Case presentation

Clinical presentation and imaging

An 80-year-old man was transferred to our institution from a local hospital because of concern for rupture or another complication of a hepatic hydatid cyst, following a one-month history of progressively worsening abdominal pain and fever. He reported having been aware of the hepatic cyst for approximately 30 years; however, this history was based solely on his recollection, as no previous imaging studies or medical records were available. The patient lived on a remote island with limited access to specialist medical care and reported having remained largely asymptomatic for many years. No previous operative treatment, antiparasitic therapy, or structured radiological surveillance could be documented. Anti-echinococcal antibodies measured by indirect hemagglutination assay were strongly positive at a titer greater than 1:1280.

Preoperative abdominal CT demonstrated a giant cystic lesion related to the right hepatic lobe and inferior hepatic surface. The lesion had a thick, extensively calcified wall and contained a clear air-fluid level together with multiple intralesional gas locules. These findings were interpreted as evidence of a chronically calcified, complicated echinococcal cyst with suspected secondary bacterial infection, which was subsequently confirmed by intraoperative cyst-fluid culture yielding Escherichia coli. The lesion exerted marked mass effect on the adjacent upper abdominal viscera. A definite communication with the colon or biliary tree was not demonstrated on the available images.

Because of the symptomatic presentation, fever, radiological evidence of a complicated infected lesion, and concern for progressive local inflammatory disease, emergency operative exploration was undertaken. The key preoperative CT findings are shown in Figure 1A-1C.

Figure 1. Preoperative abdominal CT findings.

(A) Coronal image showing a giant hepatic cystic lesion with dense peripheral calcification (arrow). (B) Axial image demonstrating an air-fluid level and multiple intralesional gas locules (arrow). (C) Sagittal image showing the anterior and inferior extent of the lesion and additional intralesional gas (arrow). The imaging findings suggested secondary bacterial infection, which was subsequently confirmed by intraoperative cyst-fluid culture yielding Escherichia coli. A definite fistulous communication with the biliary or gastrointestinal tract was not demonstrated.

Intraoperative findings and management

A midline laparotomy was performed. A very large echinococcal cyst was identified arising from the inferior surface of the liver. The lesion displaced the stomach and transverse colon and extended inferiorly toward the right iliac fossa. Dense chronic inflammatory and fibrotic adhesions completely obliterated the normal tissue planes between the cyst and the anterior abdominal wall, transverse mesocolon, transverse colon, second portion of the duodenum, and anterior gastric wall.

Careful adhesiolysis was initiated to define the extent of disease and to protect the adjacent viscera. A second bilobed cystic lesion was identified in the retroperitoneum anterior to the right kidney. At the level of the transverse mesocolon and colon, the tissues were inseparable from the inflammatory cyst wall. Continued attempts at organ-preserving dissection were considered likely to cause bowel injury and leave nonviable or grossly involved tissue. Right hemicolectomy was therefore performed, followed by a side-to-side ileotransverse anastomosis using a linear stapling device.

The hepatic cyst was opened in a controlled manner, drained, and partially excised. The cavity contained turbid yellow-green fluid consistent with secondary infection. Complete pericystectomy or formal hepatic resection was not considered appropriate in the emergency setting because of the extensive adhesions, adjacent-organ involvement, and need to prioritize source control and safe bowel resection. Hemostasis was secured, and intraperitoneal and retroperitoneal drains were placed. The principal intraoperative findings are shown in Figure 2A-2D.

Figure 2. Intraoperative findings.

(A) Initial exposure of the giant echinococcal cyst arising from the inferior hepatic surface (arrow). (B) Thickened fibrotic cyst wall with dense inflammatory adhesions to adjacent tissues (arrow). (C) Severe inflammatory-fibrotic adhesions with obliteration of the normal dissection planes (arrow). (D) Controlled opening of the cyst revealing turbid yellow-green fluid; intraoperative culture of the cyst contents subsequently yielded Escherichia coli, confirming secondary bacterial infection (arrow).

Histopathology and postoperative course

Gross examination demonstrated multiple cystic formations and fibrotic tissue. Histopathological examination identified laminated parasitic membranes, confirming echinococcal disease. The membranes were embedded within dense fibrous tissue and were associated with extensive inflammatory infiltrates, abscess formation, necrosis, and a foreign-body giant-cell reaction. Laminated membrane fragments were also identified within fibrous adhesions on the surface of the intestinal wall. Periodic acid-Schiff with diastase staining highlighted the characteristic laminated architecture.

The multiplicity of lesions, the distribution of laminated membrane fragments within fibrotic tissue, and the extrahepatic involvement led the pathologist to raise the possibility of alveolar echinococcosis. However, species-specific PCR and immunohistochemistry with an alveolar echinococcosis-specific marker such as Em2G11 were unavailable. The final interpretation was therefore echinococcal disease with histopathological features suggestive of, but not confirmatory for, alveolar echinococcosis. Extensive fibrosis, necrosis, abscess formation, and foreign-body reaction were also recognized as findings that may occur in long-standing, secondarily infected cystic echinococcosis. Representative histopathological findings are shown in Figure 3A-3D.

Figure 3. Histopathological findings.

(A) Aggregates of laminated parasitic membranes within dense fibrous adhesions on the intestinal surface (H&E, original magnification ×20). (B) Abscess formation surrounding laminated membranes focally impregnated with bile pigment (H&E, original magnification ×100). (C) Confluent fragments of laminated membrane embedded within dense fibrous tissue with a peripheral foreign-body reaction (H&E, original magnification ×100). (D) Periodic acid-Schiff with diastase staining highlighting the laminated architecture of the parasitic membrane (original magnification ×100).

The postoperative course was uneventful. Culture of an intraoperative cyst-fluid specimen yielded E. coli, microbiologically confirming secondary bacterial infection. The patient progressively resumed oral intake and was discharged in good clinical condition on postoperative day eight. Albendazole was initiated on postoperative day one at a dose of 400 mg twice daily following infectious diseases consultation and was continued for four weeks after surgery. It was prescribed as adjunctive postoperative antiparasitic therapy after partial cyst wall excision because a residual cyst wall and a separate retroperitoneal lesion remained, and complete clearance of echinococcal disease could not be confirmed. This four-week postoperative regimen was administered as adjunctive antiparasitic therapy and did not constitute definitive long-term treatment for alveolar echinococcosis, which remained unconfirmed in the absence of species-specific testing. Long-term radiological and serological surveillance was recommended because of the residual disease and unresolved species-level diagnosis. The clinical course is summarized in Table 1.

Table 1. Clinical timeline and management.

Time point	Clinical event
Approximately 30 years before admission	Patient-reported diagnosis of a hepatic echinococcal cyst approximately 30 years earlier; no previous medical records, imaging studies, or documented treatment were available.
One month before admission	Progressive abdominal pain and fever.
Preoperative assessment	Indirect hemagglutination assay titer >1:1280; CT showed a giant calcified hepatic cyst with an air-fluid level and intralesional gas.
Emergency operation	Laparotomy, right hemicolectomy with side-to-side ileotransverse anastomosis, partial cyst wall excision, drainage, and placement of intraperitoneal and retroperitoneal drains.
Postoperative pathology	Laminated echinococcal membranes with abscess formation, necrosis, dense fibrosis, foreign-body reaction, and intestinal-surface involvement. The distribution and extrahepatic involvement raised suspicion for alveolar echinococcosis, although the findings were not species-specific and could overlap with severely complicated cystic echinococcosis; species-level confirmation was unavailable.
Postoperative day eight	Discharged in good clinical condition on albendazole 400 mg twice daily, with a planned total postoperative treatment duration of four weeks.
After discharge	Long-term imaging and serological surveillance recommended because of residual disease and the separate retroperitoneal lesion.

Discussion

This case demonstrates a locally aggressive surgical phenotype of hepatic echinococcosis. The lesion was not merely large; it was chronically calcified, infected, and associated with severe fibrotic inflammation that erased the operative planes between the liver, stomach, duodenum, transverse mesocolon, colon, abdominal wall, and retroperitoneum. The decisive intraoperative problem was not a preoperatively established fistula but the inability to separate the colon and mesocolon safely from the inflammatory cyst wall.

Complicated cystic echinococcosis can account for much of this behavior. Intracystic gas and an air-fluid level are recognized indirect signs of infection or communication with the biliary or gastrointestinal tract [5,6]. Bacterial superinfection promotes abscess formation, fibrosis, and adherence to adjacent organs. In the present patient, secondary bacterial infection was microbiologically confirmed by an intraoperative cyst-fluid culture yielding E. coli. Long-standing calcification further reduces tissue compliance and may make complete pericystectomy technically hazardous. In the present patient, the CT findings accurately anticipated a technically demanding operation, although they did not establish a fistulous tract.

Colonic involvement by hydatid disease is exceptionally uncommon. The systematic review by Latatu-Córdoba et al. identified nine cases published through 2018; most represented primary colonic disease, direct fistulization from a hepatic or splenic cyst, intraluminal migration, hemorrhage, or mechanical obstruction [11]. Colon resection was frequently required when the bowel was directly involved or when local disease could not be safely separated. Astarcioglu et al. described an isolated mesosigmoidal hydatid cyst presenting with colonic obstruction that required Hartmann’s procedure and segmental colectomy [12]. Bougioukas et al. reported a hepatic hydatid cyst perforating the right colon that was treated by partial cystectomy, omentoplasty, and right hemicolectomy [13]. Restivo et al. described a calcified hepatic cyst migrating through a hepatocolonic fistula and causing left-colon obstruction [14]. A subsequent case report by Ramasamy et al. described spontaneous rupture into the transverse colon [15], while Kafadar reported a primary left-sided colonic cyst treated by laparoscopic segmental resection [16].

Our patient differs from the typical fistula-dominant pattern. No definite cystocolonic communication was demonstrated radiologically or described intraoperatively. Right hemicolectomy was instead required because dense inflammatory-fibrotic adherence had destroyed the dissection plane and made bowel preservation unsafe. This distinction is clinically relevant: in complicated hydatid disease, resection of adjacent bowel may be necessary even when there is no macroscopic perforation or proven fistula.

The histopathological interpretation requires equal caution. Laminated membranes establish echinococcal disease but do not by themselves identify the causative species. Alveolar echinococcosis typically produces small irregular vesicles, infiltrative growth, and parasite-associated fibrosis, whereas cystic echinococcosis more often forms a larger, well-defined cyst. However, morphology may overlap in fragmented, treated, infected, or extensively fibrotic specimens [9]. Em2G11 immunohistochemistry can substantially improve the specific histological diagnosis of alveolar echinococcosis, and molecular testing can provide species-level confirmation [10].

In this case, multiplicity, retroperitoneal disease, membrane fragments within fibrous intestinal adhesions, and the pathologist’s overall assessment raised legitimate suspicion for alveolar echinococcosis. Conversely, the 30-year history of a known hepatic hydatid cyst, giant calcified cavity, air-fluid level, abscess formation, and emergency presentation are also compatible with severely complicated long-standing cystic echinococcosis. It would therefore be scientifically inappropriate to describe the case as confirmed E. multilocularis infection. The most defensible diagnosis is hepatic echinococcosis with locally aggressive extrahepatic inflammatory extension and histopathological features raising suspicion for alveolar echinococcosis, without species-level confirmation.

The operative strategy was determined by source control and anatomical safety. Radical hepatic resection may be appropriate for selected resectable alveolar disease, and total pericystectomy is an option for selected cystic lesions [2,4,7]. In an emergency involving an infected giant cyst with obliterated planes and bowel involvement, however, the priority is safe control of sepsis, avoidance of uncontrolled contamination, resection of nonseparable or injured bowel, and adequate drainage. Partial cyst wall excision and right hemicolectomy were therefore reasonable within the constraints of the operative field.

Postoperative management should reflect the residual disease burden and diagnostic uncertainty. Albendazole is commonly used after surgery for complicated cystic echinococcosis and is central to the management of alveolar echinococcosis [2,4,7]. Because complete parasite clearance was not demonstrated and a separate retroperitoneal lesion was present, prolonged multidisciplinary follow-up is important. Cross-sectional imaging, liver biochemical testing, blood counts, monitoring for albendazole toxicity, and serial echinococcal serology may assist surveillance, although serological trends must be interpreted alongside imaging.

The principal limitations are the absence of species-specific PCR or Em2G11 immunohistochemistry, the limited available preoperative imaging series, and the absence of documented long-term outcome data at the time of manuscript preparation. These limitations prevent a definitive distinction between alveolar echinococcosis and complicated cystic echinococcosis and preclude conclusions regarding late recurrence. Nevertheless, this case illustrates that long-standing hepatic echinococcosis may mimic locally invasive malignancy, obliterate normal anatomical planes, and necessitate multivisceral resection even in the absence of a demonstrable fistula.

Focused literature review

A focused PubMed/MEDLINE and reference-list search was performed through July 2026 using combinations of the terms “echinococcosis”, “hydatid cyst”, “colon”, “colonic involvement”, “cystocolonic fistula”, “hepatic hydatid cyst”, and “colectomy”. English-language case reports describing direct colonic disease, fistulization, intraluminal migration, or bowel resection were reviewed. This was a focused narrative update rather than a systematic review; Table 2 presents representative reports that illustrate the principal mechanisms of colonic involvement and the distinction of the present case.

Table 2. Representative published reports of colonic involvement in echinococcosis.

Report	Age/sex	Source/site	Mechanism of colonic involvement	Presentation	Management
Astarcioglu et al. (2001) [12]	61/male	Primary mesosigmoidal cyst	Extrinsic and mesenteric involvement causing obstruction	Colonic obstruction	Hartmann procedure with segmental colon resection
Bougioukas et al. (2009) [13]	76/female	Hepatic cyst and synchronous ovarian cyst	Perforation into the right colon	Complicated right-sided hepatic hydatid disease	Partial cystectomy, omentoplasty, right hemicolectomy, and hysterectomy
Restivo et al. (2010) [14]	64/male	Calcified hepatic cyst	Migration through a hepatocolonic fistula into the left colon	Left-colon obstruction	Endoscopic removal of the migrated calcified cyst
Ramasamy et al. (2021) [15]	32/female	Hepatic cyst	Spontaneous rupture into the transverse colon	Abdominal symptoms from fistulization	Operative management of the fistulized lesion
Kafadar (2021) [16]	40/male	Primary left-sided colonic cyst	Cyst arising from the colon wall without liver or splenic disease	Pain and lower gastrointestinal bleeding	Laparoscopic segmental colectomy with anastomosis
Present case	80/male	Long-standing giant hepatic lesion with a separate retroperitoneal cystic lesion	Extensive inflammatory adherence without a documented fistula	Pain, fever, infected calcified cyst, and obliterated tissue planes	Right hemicolectomy, side-to-side ileotransverse anastomosis, partial cyst wall excision, and drainage

Conclusions

Chronic hepatic echinococcosis may occasionally present as a locally destructive inflammatory process rather than a discrete, readily separable cyst. Infection, calcification, fibrosis, and extensive extrahepatic inflammatory adherence can obliterate normal tissue planes and necessitate multivisceral resection, even in the absence of a documented cystocolonic fistula.

Histopathological findings in this case raised suspicion for alveolar echinococcosis; however, definitive species identification was not possible because species-specific molecular and immunohistochemical testing was unavailable. The case should therefore be regarded as hepatic echinococcosis with features suggestive of, but not confirmatory for, alveolar echinococcosis. This case highlights the diagnostic limitations of routine morphology and serology and the importance of integrating imaging, intraoperative findings, pathology, and species-specific testing whenever available. In complicated hepatic echinococcosis, emergency surgical management should remain guided by source control, anatomical safety, and resection of nonseparable involved tissues when necessary.