Translate this page into:
Extremely rare pediatric omental and pelvic hydatid cysts with associated omental torsion: A case report
*Corresponding author: Sunanda Samanta, Department of Radiodiagnosis, Choithram Hospital and Research Centre, Indore, Madhya Pradesh, India. sunandasamanta1992@gmail.com
-
Received: ,
Accepted: ,
How to cite this article: Joglekar A, Samanta S, Bhagat P, Bhalgat S. Extremely rare pediatric omental and pelvic hydatid cysts with associated omental torsion: A case report. Case Rep Clin Radiol. doi: 10.25259/CRCR_150_2025
Abstract
Hydatid disease rarely involves the omentum or deep pelvic regions, particularly in pediatric patients. We report a case of an 8-year-old girl with concurrent omental and deep pelvic hydatid cysts, complicated by omental torsion. Contrast-enhanced computed tomography (CECT) and magnetic resonance imaging accurately localized the cysts, differentiated them from adnexal structures, and revealed the omental torsion. Surgical excision confirmed hydatid cysts at both sites. This case underscores the diagnostic value of multimodality imaging in rare extrahepatic hydatid presentations in children.
Keywords
Case report
Omental hydatid cyst
Omental torsion
Pediatric abdomen
Pelvic hydatid cyst
INTRODUCTION
Hydatid disease, caused by Echinococcus granulosus, predominantly affects the liver and lungs. Peritoneal and pelvic involvement is uncommon, reported in only a minority of abdominal cases, and is usually secondary to hepatic disease. However, rare primary omental or pelvic hydatid cysts have been described.[1,2] Omental cysts may occasionally undergo torsion, presenting with acute or subacute abdominal pain and mimicking other surgical emergencies.[3] Deep pelvic cystic lesions in children are uncommon and may arise from developmental, enteric, or infectious etiologies. Accurate radiologic characterization is crucial for differentiating these lesions from adnexal or other pelvic structures, guiding surgical planning, and preventing inadvertent complications. We report a pediatric case of concurrent omental and deep pelvic hydatid cysts with omental torsion, highlighting the imaging features, differential diagnosis, surgical findings, and key learning points from this exceptionally rare presentation.
CASE REPORT
An 8-year-old female presented with insidious-onset lower abdominal pain for 10 days, intermittent and aggravated by bending or micturition. There was no history of fever, vomiting, trauma, or previous surgery. Abdominal examination revealed a firm, mobile hypogastric mass measuring approximately 8 × 8 cm. Vital parameters were stable.
Imaging findings
Computed tomography (CT) abdomen and pelvis
CECT demonstrated a thin-walled unilocular cyst in the lower abdomen (≈6.5 × 8.2 × 6.2 cm) with subtle mural nodular projections [Figure 1]. Adjacent omental fat along the left lateral wall showed concentric swirling of vessels and fat stranding – the classic “whirl sign” – consistent with omental torsion. A second multiloculated cyst (≈4.3 × 6.3 × 5.8 cm) was noted in the right rectouterine space, displacing the rectum posteriorly and to the left. The uterus and urinary bladder lie anterior to the lesion, with mild dependent pelvic free fluid. No hepatic, splenic, or mesenteric cysts were seen.
- Computed tomography images demonstrating omental and pelvic cysts with associated omental torsion. (a) Axial contrast-enhanced computed tomography (CECT) showing omental cyst (black arrow) with wall nodularity (white arrow). (b) Axial CECT showing adjacent fat-density structure along the left lateral cyst wall (white arrow), suggestive of omental torsion. (c) Axial CECT demonstrating twisted omental vessels (white arrow) – the “whirl sign.” (d) Coronal CECT showing omental cyst (white arrow) and adjacent fat-density structure (black arrow) consistent with torsion. (e) Axial CECT image showing multiloculated rectovesical cyst (long grey arrow) with mass effect on the rectum and uterus. (f) Sagittal CECT demonstrating multiloculated rectovesical cyst (white arrow), omental cyst (*), and urinary bladder (#).
Magnetic resonance imaging (MRI) pelvis
MRI confirmed both cysts as T1 hypointense and T2 hyperintense with thin walls [Figure 2]. The omental cyst demonstrated subtle mural nodularity, and the multiloculated rectouterine cyst displaced adjacent pelvic viscera. The uterus was anteriorly displaced between the cysts and bladder, while both ovaries were distinctly visualized and separate from the lesions, confirming extra-adnexal origin.
- Magnetic resonance imaging showing omental and deep pelvic hydatid cysts. (a) Axial T2-weighted short tau inversion recovery (STIR) image demonstrates a well-defined omental cyst (#) and a multiloculated retrorectal cyst (*) with both ovaries (white arrows) seen separately from the lesions, confirming an extra-ovarian origin. (b) Axial T2-weighted STIR image shows the omental cyst with focal wall nodularity (white arrow). (c) Sagittal T2-weighted STIR image demonstrates the omental cyst (#) with wall nodularity (white arrow) and the multiloculated rectovesical cyst (*); note the compressed uterus (white arrowhead) displaced between the rectovesical cyst and urinary bladder.
Surgery and histopathology
Laparotomy revealed a 10 × 10 cm omental cyst adherent to a twisted, ischemic omental segment, and a 6 × 4 cm multiloculated rectouterine cyst [Figure 3]. Both cysts were completely excised. Gross specimens showed pearly white laminated membranes with clear fluid. Histopathological examination revealed laminated eosinophilic membranes with attached brood capsules and scolices, confirming E. granulosus infection. The omental segment showed ischemic changes consistent with torsion. The post-operative recovery was uneventful, and the patient was commenced on albendazole. The patient was discharged in stable condition. She has not yet reported for her scheduled postoperative follow-up at the time of submission.
- Gross surgical and histopathological findings of omental and pelvic hydatid cysts with omental torsion. (a) Resected omental specimen showing a smooth-walled cystic mass with a twisted, discolored (black arrow) segment of attached omentum – indicative of omental torsion and ischemic changes. (b) Multiloculated, smooth-walled rectovesical cystic mass. (c and d) Cut sections of the omental cyst revealing a pearly white daughter cyst within a larger cystic cavity filled with clear fluid – typical of hydatid disease. (e) Cut section of the rectovesical cyst showing pearly white laminated membranes. (fh) Histopathological images (hematoxylin and eosin) from both omental (f) and rectovesical (g and h) cysts at 100x (f and g) and 200x (h) showing laminated membranes and brood capsules (black arrows).
DISCUSSION
Hydatid disease remains a significant health concern in endemic regions, transmitted through contact with infected canines or contaminated food. The liver (≈70%) and lungs (≈20%) are the predominant sites of involvement, while peritoneal hydatidosis is rare (<2%) and usually secondary to hepatic rupture. Primary omental or pelvic hydatid cysts, particularly with torsion, are exceedingly uncommon in children.[1-3]
Pathogenesis
Primary peritoneal hydatidosis may occur through hematogenous spread, lymphatic dissemination, or transcoelomic seeding following unnoticed minor cyst rupture. In this case, the absence of hepatic involvement and the presence of isolated omental and pelvic cysts favor a diagnosis of primary peritoneal hydatidosis. Omental torsion in this setting likely results from mechanical traction and altered mobility caused by the mass effect of the cyst, compounded by sudden changes in intra-abdominal pressure or minor trauma. The parasitic cyst may serve as a pivot point, predisposing the omentum to twisting.
Role of imaging
Cross-sectional imaging is critical for diagnosis and surgical planning. CT provides excellent delineation of cyst morphology, wall features, and complications such as torsion. The “whirl sign” – twisting of omental vessels and fat – is pathognomonic for omental torsion.[4,5] MRI complements CT by accurately defining relationships with pelvic viscera; confirming extra-adnexal location; and differentiating from ovarian, mesenteric, or enteric cysts.
Typical hydatid cysts may show daughter cysts, detached membranes (“water-lily sign”), or calcified walls.[1,2] However, atypical lesions can appear unilocular or multilocular with subtle wall irregularities.
In endemic regions, the presence of multiple cystic lesions in distinct compartments without solid enhancement or bowel communication should prompt consideration of hydatid disease, even in the absence of classical features.
Previous literature describes only a few cases of extrahepatic peritoneal or omental hydatid disease, mostly in adults and frequently associated with a hepatic primary or prior surgery.[1] Adult reports, such as that by Karagülle et al., have noted omental hydatid cysts presenting with acute abdomen and torsion, often mimicking appendicitis or adnexal pathology.[3] Pediatric cases are extremely rare; the report by Khalili et al. described primary omental torsion in a child with a similar presentation.[4] Surgical reviews, including that by Itenberg et al., emphasize the diagnostic utility of CT in detecting the “whirl sign” and the importance of timely surgical management.[5] Compared with these, our case is unique for demonstrating concurrent omental and deep pelvic hydatid cysts without hepatic involvement in a child, both histologically confirmed – an exceptionally rare dual-site manifestation successfully treated with complete excision and albendazole therapy.
Besides torsion, reported complications include secondary infection, rupture with anaphylaxis, intraperitoneal dissemination, adhesions, and compression of adjacent viscera. Imaging may reveal wall thickening, air-fluid levels (infection), or irregular cyst margins with peritoneal free fluid (rupture). Recognition of these features is vital for timely surgical intervention and prevention of recurrence.
Omental torsion is a rare surgical emergency that may occur secondary to cystic lesions, tumors, or focal adhesions. Radiologically, the whirl sign is diagnostic. In hydatid disease, torsion can arise due to altered weight distribution or adherence of the cyst to adjacent structures, predisposing the omentum to twist. Early recognition allows prompt surgical management, preventing infarction and necrosis.[4,5]
DIFFERENTIAL DIAGNOSIS
Extrahepatic cystic lesions in children may mimic developmental or lymphatic cysts. Imaging and clinical correlation are crucial for differentiation [Table 1].
| Entity | Usual site | Imaging features | Distinguishing features |
|---|---|---|---|
| Hydatid cyst | Omentum, peritoneum, pelvis | Unilocular or multilocular, mural nodules, daughter cysts | Multiple cysts, endemic region |
| Lymphatic malformation | Mesentery, retroperitoneum | Multiloculated, fluid-fluid levels | No mural nodularity or calcification |
| Enteric duplication cyst | Adjacent to bowel | Double wall (“gut signature”) may communicate with bowel | Peristaltic activity, GI continuity |
| Omental/Mesothelial cyst | Omentum, mesentery | Simple, unilocular, thin-walled | No mural nodules or enhancement |
| Tailgut cyst | Retrorectal | Multiloculated, posterior to rectum | Midline or presacral location, non-communicating |
GI: Gastrointestinal
Management and outcome
Complete surgical excision remains the mainstay of treatment, with care to avoid cyst rupture and spillage. Albendazole therapy is recommended postoperatively to minimize recurrence risk.
CONCLUSION Public health relevance
Hydatid disease continues to pose a burden in endemic regions due to close human-animal contact and inadequate deworming of domestic dogs. Awareness among radiologists and clinicians is essential for early recognition of atypical presentations and prevention of complications through timely intervention.
Clinical significance
This case highlights:
Rare dual-site extrahepatic hydatid disease without hepatic involvement
Omental torsion as a diagnostic and surgical challenge.
The crucial role of CT and MRI in localization, differential diagnosis, and detection of complications.
TEACHING POINTS
Hydatid cysts should be considered in the differential diagnosis of multiple intra-abdominal cystic lesions – even in the absence of hepatic involvement, particularly in endemic regions.
The CT “whirl sign” is a key diagnostic indicator of omental torsion, a rare but important surgical emergency that may complicate cystic lesions.
In hydatid disease, atypical extrahepatic cysts may lack pathognomonic features; a high index of suspicion and correlation with endemicity are essential for accurate diagnosis.
MCQs
-
Which imaging feature is most characteristic of omental torsion?
Target sign
Whirl sign
Beak sign
Onion skin sign
Answer Key: b
-
The most common route for peritoneal hydatid disease is:
Direct invasion through bowel wall
Hematogenous dissemination
Seeding from ruptured hepatic cyst
Lymphatic spread
Answer Key: c
-
MRI confirmation of extra-adnexal cystic lesions depends on:
Absence of internal septations
Normal ovaries visualized separately from the cysts
High T2 signal
Mural enhancement
Answer Key: b
Acknowledgment:
The authors acknowledge the use of an AI-based language tool (ChatGPT and OpenAI) for the refinement of grammar and flow. All radiologic interpretations, content, and final decisions were made by the authors.
Ethical approval:
Institutional Review Board approval is not required.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that they have used an AI-based language tool (ChatGPT and OpenAI) for the refinement of grammar and flow. No AI tool was used for image creation.
Financial support and sponsorship: Nil.
References
- Hydatid disease: Radiologic and pathologic features and complications. Radiographics. 2000;20:795-817.
- [CrossRef] [PubMed] [Google Scholar]
- Hydatid disease from head to toe. Radiographics. 2003;23:475-94.
- [CrossRef] [PubMed] [Google Scholar]
- Acute abdomen caused by primary torsion of the omentum in hydatid disease. Int Surg. 2009;94:279-81.
- [Google Scholar]
- Omental torsion mimicking acute appendicitis in a 7-year-old boy: A case report. J Med Case Rep. 2022;16:286.
- [CrossRef] [PubMed] [Google Scholar]
- Modern management of omental torsion and omental infarction: A surgeon's perspective. J Surg Educ. 2010;67:44-7.
- [CrossRef] [PubMed] [Google Scholar]