Spleen cyst: causes and symptoms

A splenic cyst is a fluid-filled cyst within the parenchyma or subcapsule of the spleen. Cysts can be nonparasitic or parasitic. Nonparasitic cysts are divided into "true" cysts with an epithelial lining and "false" cysts resulting from injury or inflammation. Vascular and neoplastic cysts are also distinguished separately. Correct classification is important for choosing treatment strategies, as true congenital cysts in young patients are often treated with organ-preserving methods, while parasitic cysts are managed according to echinococcosis protocols. [1]

Most nonparasitic cysts are small and asymptomatic, detected incidentally during ultrasound or CT scanning. Symptoms arise with enlargement, bleeding into the cavity, infection, or rupture. Pain on the left side under the ribs, a feeling of fullness, early satiety, and discomfort with deep inhalation are common complaints with large cysts. Congenital epithelial cysts are more common in children than in adults and require careful organ-preserving treatment. [2]

Parasitic cysts in the spleen are most often caused by cystic echinococcosis. The World Health Organization's staging ultrasound classification system divides cysts into active, transitional, and inactive stages, directly linking treatment to the stage. For active stages, antiparasitic drugs, puncture-sclerosing techniques, or surgery are used; for inactive stages, observation is acceptable. [3]

The most important principle of modern spleen surgery is to preserve functional parenchyma whenever possible. Preserving at least 25 percent of the tissue usually provides immunological protection, which is especially important for children and young adults. Total splenectomy increases the risk of severe bacterial infections, so vaccinations are planned in advance and the patient is educated on how to manage a fever. [4]

Code according to ICD-10 and ICD-11

The International Classification of Diseases, Tenth Revision, uses code D73.4 for splenic cysts. This code belongs to the group "Other diseases of the blood, blood-forming organs, and certain disorders involving the immune mechanism." When necessary, the code is qualified by accompanying diagnoses, such as abscess, rupture, or parasitic origin. [5]

In the International Classification of Diseases, Eleventh Revision, splenic cysts are classified under block 3B81.5, "Cyst or pseudocyst of spleen," which includes the subcategories "Pseudocyst of spleen," "Epithelial cyst of spleen," "Other specified cysts of spleen," and "Splenic cyst, unspecified." This level of detail helps to understand the pathogenesis and select appropriate treatment and monitoring strategies. [6]

Table 1. Diagnosis codes for splenic cysts

Classification	Main code	Transcript	Comment
International Classification of Diseases, Tenth Revision	D73.4	Spleen cyst	Used for non-parasitic and parasitic cysts in the absence of a more specific code
International Classification of Diseases, Eleventh Revision	3B81.5	Cyst or pseudocyst of the spleen	It has subcategories: pseudocyst, epithelial, other, unspecified
[7]

Epidemiology

Splenic cysts are rare. According to autopsy series and reviews, the incidence rate is approximately 0.07-0.13 percent. Their prevalence in clinical practice is higher due to the widespread use of ultrasound and computed tomography. True epithelial cysts are more often diagnosed in children and young adults. [8]

Some publications indicate that with the increasing number of instrumental studies, the proportion of incidental findings is approaching 1 percent of those examined, although this reflects detection rate rather than true prevalence. Large series confirm that most nonparasitic cysts are asymptomatic and do not require immediate intervention. [9]

Giant primary nonparasitic cysts larger than 10 cm are extremely rare and constitute a small proportion of all splenic cysts. However, it is the larger formations that most often cause clinical manifestations and complications. [10]

Parasitic cysts of the spleen constitute a small proportion of all echinococcosis lesions, but are important in regions where the disease is endemic. In various series, the spleen's share of all echinococcosis lesions is estimated at several percent, and the age of patients varies widely. [11]

Table 2. Epidemiological landmarks

Indicator	Rough estimate	Source
Frequency of detection of splenic cysts at autopsies	0.07-0.13%	Review and mini-review
The proportion of incidental findings in visualization	Up to 1% of those examined	Reports of increased detection rates
"Giant" primary cysts >10 cm	Rarely	Clinical series
The proportion of the spleen among all localizations of echinococcosis	A few percent	Clinical reviews
[12]

Reasons

Non-parasitic cysts are classified into congenital epithelial variants and acquired pseudocysts. Congenital cysts arise from epithelial inclusions during embryogenesis and are most often found in children and young adults. Pseudocysts form following trauma, hemorrhage into the splenic parenchyma, or inflammation. [13]

True epithelial cysts are heterogeneous in origin: epidermoid, mesothelial, and endothelial variants are found. Immunohistochemical expression of neutral mucin production markers and, sometimes, tumor antigens has been described in their walls, which explains the possible increase in levels of certain serum markers. [14]

Parasitic cysts are caused by the larval forms of tapeworms of the genus Echinococcus. The most significant parasite in humans is Echinococcus granulosa, which forms cysts with characteristic ultrasound features and a staged evolution. Alveolar echinococcosis with infiltrative growth is less common. [15]

Individual vascular and neoplastic cysts of the spleen, such as lymphangiomas and hemangiomas with cystic areas, belong to a different group of causes and require differentiation based on imaging and morphology data. [16]

Risk factors

No reliable modifiable risk factors have been identified for nonparasitic cysts due to the rarity of the condition and the lack of population-based studies. Congenital epithelial cysts are associated with embryonic mechanisms rather than lifestyle. For pseudocysts, a history of blunt abdominal trauma is an obvious predictor. [17]

For parasitic cysts, key determinants include residence or extended travel to regions with endemic echinococcosis, as well as professional contact with animals without adequate deworming. These risk factors are taken into account when interpreting ultrasound images and choosing serological testing. [18]

In pediatrics, attention is paid to the association of congenital cysts with other developmental anomalies of the abdominal organs, although the cause-and-effect relationships often remain unclear. This influences the scope of preoperative examination and the planning of organ-preserving surgery. [19]

A separate practical "risk group" includes patients with large cysts over 5-6 cm, who are more likely to experience symptoms and complications, which serves as a trigger for active treatment. Threshold sizes vary between centers and are based on the combined clinical presentation and growth dynamics. [20]

Table 3. Risk factors and context

Factor	Type of cysts	Comment
Blunt abdominal trauma	Pseudocyst	A common cause in adults
Endemic region for echinococcosis	Parasitic cyst	Basis for testing and staging
Congenital anomalies	True epithelial cyst	Occurs in children and affects treatment plan
Dimensions more than 5-6 cm	Any	Higher risk of symptoms and complications
[21]

Pathogenesis

True epithelial cysts are lined with a single-layer of squamous, cuboidal, or ciliated epithelium. In some cases, the lining cells produce carbohydrate antigen 19-9 and carcinoembryonic antigen, which explains the false-positive elevation of these markers in the blood. After cyst removal, marker levels usually return to normal. [22]

Pseudocysts lack an epithelial lining and develop at the site of a hematoma or necrosis of the splenic parenchyma following trauma or infection. The wall is composed of fibrous tissue. These cysts have a higher risk of recurrence after simple drainage and often require more radical excision of the wall. [23]

Parasitic cysts consist of an outer fibrous capsule of the host and a parasitic membrane containing fluid and daughter vesicles. As the contents evolve, they lose viability, the cyst calcifies, and becomes inactive, allowing for safe observation of such cases in the absence of complications. [24]

Vascular and tumor cysts are associated with abnormal development of lymphatic or blood vessels, or represent cystic changes within benign tumors. They are less common, but require oncological vigilance if they present atypically. [25]

Symptoms

Small cysts are often asymptomatic and are discovered incidentally. As the cavity enlarges, a dull ache and a feeling of heaviness in the left hypochondrium, early satiety, and discomfort when bending over occur. Nausea and flatulence are sometimes associated with compression of the stomach and colon. [26]

Acute symptoms are associated with hemorrhage, infection, or rupture of the cyst: sudden, sharp pain, pallor, sweating, dizziness, and a drop in blood pressure require emergency care. In children, large cysts may present with an enlarged spleen and a sensation of a "lump" on the left side under the ribs. [27]

Parasitic cysts can cause allergic reactions upon rupture, including anaphylactoid reactions. A prolonged asymptomatic course does not preclude the risk of complications, so the stages and dynamics are confirmed by serial studies. [28]

Some patients have false-positive elevations of carbohydrate antigen 19-9 and carcinoembryonic antigen, which raises concern about oncology. In the context of an epithelial cyst, such elevations do not indicate cancer and usually resolve after treatment. [29]

Classification, forms and stages

Splenic cysts are generally classified as parasitic and non-parasitic. Non-parasitic cysts are subdivided into true epithelial (including epidermoid, mesothelial, and endothelial) and false post-traumatic pseudocysts. Vascular and neoplastic cystic formations are also distinguished. [30]

For echinococcal cysts, the World Health Organization staging system is used: active stages CE 1 and CE 2, transitional CE 3, inactive CE 4 and CE 5. The stage is determined by ultrasound features and dictates the choice of treatment - from observation to puncture techniques and surgery. [31]

In practical surgery, the size, location relative to the splenic hilum, and proximity to segmental vessels are also taken into account. These parameters influence the choice of organ-preserving technique, the possibility of partial splenectomy, and the risk of recurrence after fenestration. [32]

In pediatrics, the guideline is a combination of size and symptoms: if the diameter is less than 5 cm and there are no complaints, observation is most often chosen; if there are symptoms or a size of 5 cm or more, intervention with maximum preservation of the parenchyma is indicated. [33]

Table 4. Classification of spleen cysts

Group	Subtype	Key Features	Tactical significance
Non-parasitic	True epithelial	Epithelial lining; congenital nature	Most often, organ-preserving surgery
Non-parasitic	Pseudocysts	No epithelium; post-traumatic wall	Higher risk of recurrence after simple drainage
Parasitic	Echinococcus	Stages of CE 1-CE 5 according to ultrasound signs	Treatment is strictly staged.
Others	Vascular, tumor	Lymphangioma, hemangioma, etc.	Differential diagnosis is needed
[34]

Complications and consequences

Large cysts can rupture, bleeding into the abdominal cavity or into the cyst cavity, causing severe pain and signs of internal bleeding. Infection leads to abscess formation and fever. These conditions require urgent evaluation and often surgical treatment. [35]

Parasitic cysts are at risk of rupture, leading to severe allergic reactions and parasite dissemination. Therefore, antiparasitic therapy protocols and interventions with measures to prevent relapse and dissemination are used for active stages. [36]

Recurrences are possible after organ-preserving interventions, especially if a portion of the viable wall is left. The risk is lower with maximal excision of the wall or with partial splenectomy by segment. [37]

Following total splenectomy, the lifelong risk of invasive bacterial infections increases. This risk can be minimized by vaccination against pneumococcal, meningococcal, and Haemophilus influenzae infections, annual influenza vaccination, and information about the early use of antibiotics for fever. [38]

When to see a doctor

Sudden, intense pain in the left hypochondrium, weakness, dizziness, fainting, a drop in blood pressure, and cold sweat are reasons for urgent medical attention—these are possible signs of a cyst rupture and internal bleeding. Delaying in this situation is dangerous. [39]

High fever, chills, and increasing pain in the left hypochondrium, which may indicate a cavity infection, require immediate evaluation. In the case of a parasitic cyst, allergic reactions, rash, and difficulty breathing, especially after abdominal trauma, are cause for concern. [40]

A planned consultation is recommended in cases of persistent dull pain on the left side, a feeling of fullness, early satiety, or the incidental discovery of a cyst on ultrasound to determine the nature of the cavity, its stage, and a plan for monitoring or treatment. For children, an examination by a specialized surgeon with experience in organ-preserving surgery is recommended. [41]

Following surgery, a schedule of follow-up imaging and physical activity recommendations should be followed. For total splenectomy, a vaccination schedule and fever reminder are discussed. [42]

Diagnostics

The primary imaging test is an abdominal ultrasound. This allows confirmation of the cystic nature of the lesion, assessment of wall thickness, the presence of septa, daughter vesicles, calcifications, and approximate size. If echinococcosis is suspected based on ultrasound findings, the stage is immediately determined according to the World Health Organization classification. [43]

Computed tomography and magnetic resonance imaging (MRI) clarify the location relative to the splenic hilum, vessels, and adjacent organs, and identify hemorrhage into the cavity and dense components. MRI better reproduces ultrasound criteria for echinococcosis activity when ultrasound is insufficiently informative. [44]

Serological tests for echinococcosis are considered auxiliary: a negative result helps exclude an active parasitic cause, while a positive result requires interpretation based on stage-specific imaging findings. Biochemical and general clinical analyses are used for preoperative preparation and to monitor the safety of therapy. [45]

Determination of carbohydrate antigen 19-9 and carcinoembryonic antigen is sometimes performed when an epithelial cyst is suspected, but an increase in these levels is not a sign of cancer in this context and should not determine tactics without taking morphology into account. In case of atypical signs, the question of morphological verification is decided during organ-preserving surgery. [46]

Table 5. Diagnostic minimum and its tasks

Stage	What does it give?	Why is it needed?
Ultrasound examination	Size, wall, partitions, daughter vesicles	Basic verification and staging of echinococcosis
Computed tomography	Exact location, calcifications, complications	Planning access and scope of intervention
Magnetic resonance imaging	The nature of the content, agreement with the stage	Clarification of the activity of echinococcosis
Serology for echinococcosis	Confirmation of parasitic etiology	Decision on antiparasitic tactics
Markers: carbohydrate antigen 19-9, carcinoembryonic antigen	Possible clue of epithelial nature	Cannot be interpreted as cancer markers in isolation
[47]

Differential diagnosis

Echinococcal cyst. It is differentiated by stage-specific ultrasound features (double contour, daughter vesicles, "snow storm," wall calcification in inactive stages) and by epidemiological history. Treatment is strictly stage-specific and differs from that for non-parasitic cysts. [48]

Pseudocyst following trauma. History of abdominal trauma. Visualization reveals a capsule without epithelium, possible calcifications in the wall, and heterogeneous contents. The risk of recurrence is higher with simple drainage, so decapsulation or partial splenectomy is preferred. [49]

Vascular and tumor cysts. Lymphangiomas and hemangiomas have characteristic signal characteristics and contrast enhancement on magnetic resonance imaging and computed tomography. When in doubt, morphological assessment is performed during surgery. [50]

Cysts of adjacent organs. Pseudocysts of the tail of the pancreas and cysts of the left kidney can mimic splenic cysts. Differentiation is based on the relationship to the splenic hilum, respiratory mobility, and vascular anatomy on computed tomography. [51]

Treatment

Observation is warranted for asymptomatic, small, non-parasitic cysts. If there is no dynamic growth and the diameter is up to 5 cm, regular ultrasound monitoring is safe. This approach reduces the number of unnecessary interventions without worsening outcomes. [52]

In cases of symptomatic or rapidly growing nonparasitic cysts, minimally invasive organ-preserving approaches are considered. For superficial thin-walled cysts, laparoscopic fenestration (dome excision) with coagulation of the cyst bed is appropriate. This method ensures rapid recovery, but recurrence is more common than after more radical wall excision. [53]

Decapsulation, i.e., complete excision of the cyst wall down to the parenchyma, reduces the risk of recurrence compared to simple fenestration. The choice between these approaches depends on the capsule thickness, its location relative to the splenic capsule, and its proximity to blood vessels. [54]

Partial splenectomy is considered the "golden mean" for deep, recurrent, and large cysts, particularly at the splenic poles. Preserving at least 25 percent of the parenchyma maintains immune function, and the risk of recurrence is lower than after fenestration. Laparoscopic splenectomy demonstrates good results and a low complication rate. [55]

In children, the standard treatment for symptomatic epithelial cysts is laparoscopic partial splenectomy with careful control of segmental vessels. This approach combines radical treatment of the cyst with preservation of immune function, which is especially important in childhood. [56]

Puncture with image-guided sclerotherapy is considered in patients with high anesthetic risk or as a bridge to surgery. Ethanol or other sclerosants are used according to the center's protocols. The higher risk of recurrence compared to surgical excision of the wall should be noted. [57]

Total splenectomy remains reserved for giant cysts, multiple lesions, total involvement of the splenic hilum, or after multiple recurrences. The decision is made after discussing the risk of infection after splenectomy, planning vaccinations, and training in fever management. [58]

Treatment of echinococcal cysts is strictly staged. For active stages CE 1 and CE 3a, albendazole-based antiparasitic drugs and puncture techniques with aspiration and administration of a sclerosant according to protocol are advisable. For inactive stages CE 4 and CE 5, a watchful waiting approach is recommended in the absence of complications. The choice of treatment method is based on updated World Health Organization guidelines. [59]

In some patients, modern laparoscopic techniques with minimal incisions are used, such as the transumbilical single-port approach for partial splenectomy in children. These approaches further reduce pain and speed recovery while maintaining oncological radicality for the cyst. [60]

After any organ-preserving surgery, hemostasis control, thrombosis prevention, early mobilization, and routine imaging in the first months are important. With total splenectomy, vaccination against pneumococcus, meningococcus, and Haemophilus influenzae is vital, as is annual influenza vaccination; optimally, vaccines should be administered 14 days before the planned surgery. [61]

Table 6. Choice of treatment method

Clinical situation	Preferred approach	Plus	Restrictions
Asymptomatic nonparasitic cyst up to 5 cm	Observation	Non-surgical control	Requires observation discipline
Superficial cyst 5-10 cm with symptoms	Fenestration or decapsulation	Fast recovery	The risk of recurrence is higher than after resection
Deep, recurrent or polar cyst	Partial splenectomy	Lower risk of recurrence, preservation of function	Higher technical complexity
Multiple or giant cysts, hilum involvement	Total splenectomy	The final decision	Lifelong infectious risk
Echinococcal cyst in active stages	Albendazole preparations, puncture techniques or surgery	Reduction of recurrence and dissemination	Requires strict protocols
[62]

Prevention

There is no specific primary prevention for non-parasitic cysts. Prevention of pseudocysts involves general trauma prevention and prompt treatment of conditions that can lead to splenic infarction and subsequent cyst formation. For parasitic forms, veterinary and sanitary measures are important in endemic regions. [63]

After organ-preserving procedures, prevention of recurrence includes complete excision of the wall, coagulation of the bed, and routine imaging. For patients who have undergone total splenectomy, prevention of severe infections is based on vaccination, hygiene, and early initiation of antibiotics for fever. [64]

Patient education materials with reminders about signs of complications and follow-up appointments increase adherence and reduce the risk of late referrals. Centers with organ-preserving laparoscopic techniques are recommended for families with children. [65]

In regions with echinococcosis, a reduction in the incidence of the disease is achieved through a comprehensive approach: deworming of animals, slaughter control, health education, access to ultrasound diagnostics, and routing of patients to specialized centers. [66]

Forecast

Most patients with nonparasitic cysts have a favorable prognosis. Small, asymptomatic cysts can remain stable for years. After organ-preserving surgery, quality of life is quickly restored, and the risk of severe complications is low in experienced hands. [67]

The risk of recurrence depends on the method: it is higher after simple fenestration and lower after decapsulation or partial splenectomy. In children and young adults, preference for organ-preserving strategies ensures long-term immune safety. [68]

The prognosis for echinococcosis is determined by the stage, the quality of antiparasitic therapy, and the appropriateness of the chosen method. Inactive stages are stable during observation, while active stages respond well to stage-based interventions when protocols are followed. [69]

Total splenectomy radically solves the cyst problem but changes the risk profile. With full vaccination schedule and precautions, long-term outcomes remain favorable. [70]

Table 7. Prognostic benchmarks

Situation	Forecast	Notes
Observation of small non-parasitic cysts	Favorable	Low risk of complications with stable size
After fenestration	Favorable	The risk of recurrence is higher than after wall resection
After partial splenectomy	Favorable	Immune function is preserved, relapse is rare
Echinococcosis of inactive stages	Stable on observation	No intervention required
After total splenectomy	Favorable for vaccination	Vaccinations and training required
[71]

FAQ

Is it possible to simply observe a splenic cyst?
Yes, if it's small, not growing, and not causing symptoms. In such situations, regular ultrasound monitoring according to an agreed-upon schedule is sufficient. This decision is reconsidered if pain, an increase in size, or complications occur. [72]

What signs require immediate attention?
Sudden severe pain on the left side under the ribs, weakness, dizziness, fainting, signs of a drop in blood pressure, high fever, and chills. This could be a ruptured or infected cyst, which requires urgent evaluation. [73]

Does an elevated carbohydrate antigen 19-9 always indicate cancer?
No. In epithelial splenic cysts, carbohydrate antigen 19-9 and carcinoembryonic antigen may be elevated without cancer and usually return to normal after cyst treatment. These values are interpreted only in the context of imaging and clinical findings. [74]

How are echinococcal cysts of the spleen treated?
Treatment depends on the stage: for active stages, antiparasitic drugs and puncture techniques are used, while safety precautions are observed, or surgery is considered; for inactive stages, observation is acceptable. Follow the current recommendations of the World Health Organization. [75]

Is it necessary to remove the entire spleen?
Only if indicated: giant, multiple, or recurrent cysts, or involvement of the splenic hilum. Organ-preserving surgery is preferred whenever possible. If splenectomy is unavoidable, vaccinations and fever awareness training are mandatory. [76]