A case report of an incidentally diagnosed primary isolated splenic hydatid cyst: the therapeutic dilemma of surgery versus watchful waiting

Abstract

Introduction and importance:

The incidence of splenic hydatid cyst is 1%, and it comprises 0.5–4% of abdominal hydatid cysts. Primary hydatid cyst of the spleen is rare even in endemic areas, comprising only 2% of all splenic hydatid cysts. This case is unique due to the incidental finding of a rare isolated splenic hydatid cyst without other organ involvement. It raises surgeon awareness of atypical presentations, aiding diagnosis and guiding timely intervention versus watchful waiting.

Case presentation:

A 36-year-old female was incidentally diagnosed with a splenic hydatid cyst during radiological evaluation as part of a routine health check-up. Clinical examination revealed no significant findings, and baseline blood investigations were within normal limits. She underwent splenectomy successfully and was discharged on the fourth postoperative day with advice to continue albendazole for 1 more month.

Clinical discussion:

The membrane of a splenic hydatid cyst is typically thin, delicate, and fragile, in contrast to the hepatic hydatid cyst, which has a thicker and more robust wall. The risk of spontaneous or traumatic rupture is higher in splenic hydatid cysts compared to hepatic hydatid cysts. Thus, splenectomy is a safe and widely accepted option for splenic hydatid cysts.

Conclusion:

Watchful waiting is generally not recommended for Type I and Type III splenic hydatid cysts, even in asymptomatic or incidentally detected cases, whereas it may be considered in selected cases of hepatic hydatid cysts. In addition, watchful waiting can be considered in Type IV and Type V splenic hydatid cysts, as these represent inactive stages.

Introduction

Hydatid disease, or echinococcosis, is a parasitic infection caused by the larval stage of Echinococcus species. Three types of echinococcosis are known to affect humans: cystic echinococcosis (CE) caused by E. granulosus, alveolar echinococcosis (AE) caused by E. multilocularis, and polycystic echinococcosis (PE) caused by E. vogeli or E. oligarthus. Among these, CE and AE have a global distribution, whereas PE is geographically restricted to Central and South America[1].

HIGHLIGHTS

• The incidence of splenic hydatid cyst is 1%, and it comprises 0.5–4% of abdominal hydatid cysts.

• The membrane of a splenic hydatid cyst is typically thin, delicate, and fragile; in contrast, the hepatic hydatid cyst has a thicker and more robust wall.

• Radiological evaluation with ultrasonography (USG) and computed tomography (CT) of the abdomen helps in diagnosis and planning appropriate management.

• Total splenectomy remains the most definitive treatment option for splenic hydatid cysts.

• Watchful waiting is not recommended for Type I and Type III splenic hydatid cysts, even if asymptomatic.

Hydatid cysts can affect almost any organ in the body. The liver is the most commonly involved organ, accounting for 50–70% of cases, followed by the lungs in approximately 25% of cases. The spleen is the third most frequently affected organ. The incidence of splenic hydatid cyst is around 1%[2], comprising 0.5–4% of all abdominal hydatid disease[3]. The first case of splenic hydatid cyst was noticed during autopsy by Berlot in 1970[4]. This case is unique due to the rare isolated splenic involvement by a hydatid cyst without other organ involvement. It raises surgeon awareness of atypical presentations, aiding diagnosis and guiding timely intervention versus watchful waiting.

The work has been reported in line with the revised SCARE criteria, 2025[5].

Case presentation

A 36-year-old female, with no history of comorbidities or prior surgical interventions, was incidentally diagnosed with a splenic hydatid cyst during an ultrasonographic evaluation as part of a routine health check-up. She resided in an area where sheep farming is commonly practiced. Clinical examination revealed no significant findings, and baseline blood investigations were within normal limits. To rule out pulmonary hydatid cysts, a chest X-ray was obtained during the preoperative assessment. The results were normal, with no signs of cystic lesions or other pulmonary abnormalities. Based on these findings, further imaging with chest computed tomography (CT) was deemed unnecessary. Contrast-enhanced computed tomography (CECT) of the abdomen and pelvis showed a well-defined hypodense lesion measuring 6 × 5 × 5 cm³ involving the inferior pole of the spleen. Smaller non-enhancing hypodense areas within the lesion were noted, likely representing daughter cysts. The lesion was closely abutting the tail of the pancreas, the lower pole of the left kidney, and adjacent bowel loops medially (Fig. 1). Enzyme-linked immunosorbent assay (ELISA) for Echinococcus IgG antibodies was negative. Considering the higher risk of spontaneous or traumatic rupture associated with splenic hydatid cysts compared with hepatic hydatid cysts, the patient was planned for open splenectomy. A left subcostal incision was made, and the lesser sac was accessed. Intraoperative findings revealed a well-encapsulated hydatid cyst strictly confined to the spleen, with no evidence of rupture, spillage, or adhesion to adjacent structures such as the diaphragm, stomach, or pancreas (Fig. 2). The surrounding tissues appeared normal, with no signs of secondary involvement. A thorough exploration of the abdominal cavity confirmed the absence of additional hydatid cysts in other intra-abdominal organs. Although the abdominal cavity was carefully packed with tetras soaked in 10% povidone–iodine – the only locally available scolicidal agent – to minimize the risk of spillage and contamination, no scolicidal agent was injected directly into the cyst cavity. The gastrosplenic and splenocolic ligaments were divided and ligated, followed by division and ligation of the splenorenal and splenophrenic ligaments. Finally, the splenic artery and vein were ligated near the hilum, and the spleen was removed en masse successfully without any intraoperative complications. Preoperatively, the patient received Hemophilus influenzae type B, meningococcal, and pneumococcal vaccines 2 weeks prior to surgery, along with initiation of albendazole therapy. Her postoperative course was uneventful, and she was discharged on the fourth postoperative day with advice to continue albendazole for 1 more month. On follow-up at 3 and 6 months, the patient did not have any issues; both clinical examination and ultrasonographic evaluation were unremarkable.

Figure 1.

Axial, coronal, and sagittal sections of contrast-enhanced computed tomography (CECT) of the abdomen and pelvis showing a well-defined hypodense lesion in the spleen suggestive of a splenic hydatid cyst, with non-enhancing areas within the lesion suggestive of a daughter cyst (white arrow).

Figure 2.

Intraoperative image showing spleen (black arrow) along with intact hydatid cyst (white arrow).

Pathological findings

The specimen was received as a spleen measuring 10 cm × 4.8 cm × 4 cm, along with a cyst wall measuring 6 cm × 5 cm × 5 cm.

Histological examination (Fig. 3) revealed cystic structures lined by an innermost germinal layer. It was accompanied by an outer thick, avascular, eosinophilic, and lamellated layer. The presence of scolices and daughter cysts was also noted. Additionally, dense inflammatory infiltrates composed of neutrophils, lymphocytes, and plasma cells were observed. Thickened and congested blood vessels were also evident. Histological examination of the part of the spleen revealed normal splenic morphology.

Figure 3.

(a) 4× view showing outer acellular lamellate layer (black arrow) and inner protoscolices as shown by the white arrow. (b) 40× view showing protoscolices (white arrow) with suckers and refractile hooklets.

Discussion

Splenic hydatid cysts can be classified as either primary or secondary. A primary splenic hydatid cyst originates within the spleen itself, without evidence of hydatid disease in other organs. In contrast, secondary splenic hydatid cysts occur due to parasitic spread from other infected sites, typically as a result of systemic dissemination or intraperitoneal seeding, most often from a ruptured hepatic hydatid[6]. Primary involvement of the spleen, as observed in our case, is exceedingly rare – even in endemic regions – accounting for only about 2% of all splenic hydatid cysts[7]. The remaining 98% are secondary in nature, highlighting the importance of thoroughly evaluating other potential primary sites during diagnosis[8].

Approximately 30% of patients with splenic hydatid cysts remain asymptomatic, primarily due to the slow growth rate of the cysts (ranging from 0.3 to 2 cm per year)^[4,6^]. Others may present with nonspecific symptoms such as abdominal pain, a palpable mass, or dyspnea resulting from elevation of the left hemidiaphragm by the cyst. Additional manifestations include constipation, due to compression of the colon[4], and in rare cases, systemic hypertension caused by compression of the renal artery[9]. If the cyst compresses the splenic hilar vessels, segmental portal hypertension and progressive splenic atrophy may occur, potentially leading to complete replacement of the splenic parenchyma. Chronic pericystic inflammation can result in adhesions, which may eventually lead to fistulization of the cyst into adjacent organs such as the stomach, left colon, pancreas, left bronchus, or left kidney[10]. Similarly, traumatic or spontaneous rupture of the cyst may cause anaphylactic reactions, secondary infection, or hemoperitoneum. With progressive enlargement, the cyst may erode into adjacent organs such as the stomach[11] or diaphragm[12], potentially leading to perforation.

A negative serological result, as seen in our case, does not exclude the diagnosis of a hydatid cyst. Serological tests such as ELISA may yield false negatives due to the immune-modulating ability of Echinococcus antigens, which can inhibit B-cell activation and proliferation. Studies show that only about 54.8% of patients with early or inactive cyst stages demonstrate a positive serological response. The sensitivity of ELISA significantly increases during active cyst stages, particularly CE-2 and CE-3[13]. Furthermore, antibody detection via ELISA or immunoblotting is generally more sensitive than assays aimed at detecting Echinococcus antigens directly[14].

Recurrence of hydatid cyst is one of the major concerns in the management of hydatid cyst. The recurrence rate is reported to be in the range of 4.6–22% in different literatures[13]. Microscopic spillage of viable parasites or incomplete removal of the cyst during the initial surgery are the main causes of recurrence[14].

Ultrasonography of the abdomen and pelvis is the first-line imaging modality with a diagnostic accuracy of 90% for both screening and follow-up, as it allows classification of hydatid cysts according to the WHO classification system. CT and magnetic resonance imaging (MRI) provide superior anatomical detail and are useful for identifying extrahepatic cysts and detecting complications related to the cyst. CT is highly sensitive (94–100%) and is particularly valuable for assessing calcifications and detecting the number, size, and location of the cyst. MRI, on the other hand, is superior for evaluating the internal structure of the cyst and identifying floating or detached membrane, especially in cases with dense calcification. It is also more effective in demonstrating cyst wall defects, biliary communication, neural involvement, postsurgical residual lesions, and recurrences, as well as in differentiating hydatid cysts from simple cysts[15]. However, its high cost limits its routine use, and it is generally reserved for cases in which ultrasonography or CT findings are inconclusive or when serological tests are negative. To rule out pulmonary hydatid cyst, chest X-ray remains a reliable initial investigation, with a diagnostic accuracy of up to 99%. Chest CT may be used as an additional imaging modality when further evaluation is required, but it is generally not necessary if the chest X-ray findings are normal[16].

The membrane of a splenic hydatid cyst is typically thin, delicate, and fragile, in contrast to the hepatic hydatid cyst, which has a thicker and more robust wall. The risk of spontaneous or traumatic rupture is higher in splenic hydatid cysts compared to hepatic hydatid cysts. Therefore, watchful waiting is generally not recommended for Type I and Type III splenic hydatid cysts, even in asymptomatic or incidentally detected cases, whereas it may be considered in selected cases of hepatic hydatid cysts. In addition, watchful waiting can be considered in Type IV and Type V splenic hydatid cysts, as these represent inactive stages.

Treatment options for splenic hydatid cysts include total splenectomy and spleen-preserving procedures such as partial cystectomy, cyst deroofing followed by omentoplasty, partial splenectomy, internal drainage with cystojejunal anastomosis (cystojejunal Roux-en-Y anastomosis), and percutaneous drainage using the PAIR (puncture, aspiration, injection, re-aspiration) technique^[17,18^]. Partial cystectomy is associated with a significantly higher risk of intraoperative rupture. The delicate nature of the splenic cyst membrane makes it more susceptible to tearing or accidental spillage during surgical manipulation. In contrast, hepatic hydatid cysts usually possess a thicker and more robust pericyst, offering greater resistance to rupture. This anatomical difference is a key consideration when selecting a surgical approach, as rupture can lead to anaphylaxis, secondary dissemination, and recurrence of the disease[4]. Additionally, partial resection carries a high risk of leaving residual cyst wall, increasing the likelihood of recurrence. Although partial splenectomy is associated with a higher risk of postoperative hemorrhage, it may be considered in cases of a single, small, and peripherally located cyst, especially in young patients. Similarly, total splenectomy is indicated in cases of large cysts or when the cyst is centrally located or involves the splenic hilum. The main drawback of total splenectomy is the potential risk of overwhelming post-splenectomy infection (OPSI). However, the risk of OPSI can be effectively minimized through appropriate vaccination with Haemophilus influenzae type B, pneumococcal, and meningococcal vaccines administered 2 weeks before or after surgery, as done in our case. This concern has provided the rationale for spleen-preserving surgery, which is considered a better alternative to total splenectomy when feasible, as it preserves the immunological function of the spleen and reduces the risk of such complications[19]. In a study conducted by Atmatzidis et al, during a period of 25 years, 19 patients with splenic hydatid cyst were operated and it was concluded that there was no significant difference in the recurrence rate following splenectomy (12%) versus spleen-preserving procedure (14%). Thus, spleen preservation should be done if possible, and the procedure of choice should be selected based on the size and location of the cyst[10]. Minimally invasive laparoscopic surgery has demonstrated favorable outcomes in previous studies, with significantly reduced morbidity rates compared to the open surgical approach[19].

Spleen-preserving procedures are preferred in children, as they are at higher risk of developing post-splenectomy sepsis, with reported mortality rates exceeding 50%[4]. They are also considered in adults when the cysts are small, inactive, superficial, located at the upper or lower poles of the spleen, or when there are dense adhesions to surrounding structures. The PAIR technique is safe for Type I or II splenic hydatid cysts with a diameter <5 cm, for patients who are not fit for anesthesia or refuse surgery[16]. The alternative percutaneous approaches to PAIR are PAID (puncture, aspiration, injection, and drainage), MoCaT (modified catheterization technique), and PEVAC (percutaneous evacuation of cystic content). In case of PAID, catheter removal is recommended if drainage is ≤10 mL/day. Literature showing cases of primary isolated splenic hydatid cysts based on patients’ demographics, symptoms, diagnosis, management, and outcomes is summarized in Table 1.

Table 1.

Comparative analysis of primary isolated splenic hydatid cysts based on patients’ demographics, symptoms, diagnosis, management, and outcomes.

Case reference (year)	Patient demographics	Presentation	Diagnosis	Management	Outcomes/follow-up
Malik et al (2011)[15]	Eight patients (five females and three males) 23–45 years	Dull aching left upper abdominal pain Enlarging mass in the left upper abdomen	USG and CT abdomen and pelvis	Total splenectomy	Uneventful recovery, 3 months of albendazole therapy
Jalali et al (2024)[16]	33-year-old female	Heaviness in the left upper abdomen for 6 months	USG and CT abdomen and pelvis (12 × 9 cm2 cyst with clear wall and multivesicular content)	Open splenectomy (hydatid cyst in the upper pole of the spleen)	Uneventful, no recurrence at 1 year
Menif et al (2024)[17]	40-year-old female	Heaviness in the left upper abdomen for 2 years	USG and CT abdomen and pelvis (12 × 9 cm2 multivesicular cyst with partial wall calcification)	Open total splenectomy (cyst in the lower pole of the spleen adherent to the left kidney)	Recovered well; no recurrence at 2 years
Khefacha et al (2024)[18]	40-year-old male	Left upper abdominal pain and heaviness for 4 months	CT abdomen and pelvis (10 cm hydatid cyst of spleen)	Open total splenectomy	Recovered well; albendazole therapy for 3 months, no recurrence at 2 years
Jatal et al (2023)[19]	20-year-old female	Left upper abdominal pain and an enlarging lump for 2 years	CT abdomen and pelvis (20 × 20 × 18 cm unilocular cyst with hydatid sand in the spleen with a thin rim of splenic parenchyma)	Open total splenectomy	Recovered well; albendazole for 2 months, no recurrence at 1 year
Current case (2025)	26-year-old female	Asymptomatic, no abdominal complaints	Incidental finding on abdominal ultrasound. CT abdomen (6 × 5 × 5 cm cyst with clear wall and daughter cyst)	Open total splenectomy (cyst in the lower pole of the spleen)	Uneventful, albendazole therapy for 1 month, no recurrence at 3 months follow-up

According to WHO guidelines, for CE, albendazole should be started 1–7 days prior to surgery and continued postoperatively for 1–3 months at a dose of 10–15 mg/kg/day (up to 400 mg twice daily) in two divided doses, ideally taken with a fat-rich meal to improve absorption. The duration may be extended if clinically warranted. In the event of cyst spillage, a 2-week course of praziquantel in addition to albendazole may be considered[20]. Chemotherapy can be continued throughout life in inoperable cases or when only palliative resection is achieved[4]. Follow-up imaging is recommended at 3–6 months postoperatively and then annually for at least 5 years to evaluate treatment success and monitor for recurrence[20].

Limitations

Serological evaluation in this case was limited. Although ELISA for Echinococcus IgG was reported as negative, details regarding the assay – such as manufacturer, antigen target, cutoff values, and confirmatory tests (e.g., immunoblot or Western blot) – were not available. Repeat or confirmatory serology could not be performed due to resource constraints. These factors represent a limitation in the serological assessment of this case. Similarly, laparoscopic partial splenectomy would have been preferred; however, it could not be performed due to limited expertise in a resource-constrained setting. The patient was followed up for only 6 months due to time constraints at the time of manuscript preparation, and longer-term follow-up is required. Postoperative albendazole was administered for only 1 month in accordance with local practice. These factors represent further limitations of the case.

Conclusion

Hydatid cyst of the spleen is rare, with an incidence of 1%. Primary hydatid cyst of the spleen is extremely rare, comprising only 2% of all splenic hydatid cysts. The treatment of splenic hydatid cyst can be either total splenectomy or spleen-preserving procedures. Watchful waiting is generally not recommended for Type I and Type III splenic hydatid cysts, even in asymptomatic or incidentally detected cases, whereas it may be considered in selected cases of hepatic hydatid cysts. In addition, watchful waiting can be considered in Type IV and Type V splenic hydatid cysts, as these represent inactive stages.

Ethical approval

Ethical approval by the ethics committee is not required for a case report in our country.

Consent

Informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Sources of funding

None.

Author contributions

Constructing hypothesis for the manuscript: R.J. and S.K.G. Planning methodology to reach the conclusion: R.J., R.P., S.K.G., and M.J. Organizing and supervising the course of the article and taking responsibility: R.J., S.K.G., and A.S. Patient follow-up and reporting: R.J., S.K.G., R.P., and A.S. Logical interpretation and presentation of the results: R.J., S.K.G., R.P., R.K.G., and M.J. Construction of the whole or body of the manuscript: R.J., R.P., S.K.G., and R.K.G. Reviewing the article before submission not only for spelling and grammar but also for its intellectual content: R.J., S.K.G., R.P., R.K.G., M.J., and A.S.

Conflicts of interest disclosure

The authors declare that there is no conflict of interest regarding the publication of this paper.

Research registration unique identifying number (UIN)

Not applicable.

Guarantor

Rahul Jha.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Data availability statement

Curated data that were analyzed are available from the corresponding author upon request.