What is the best course of action for an adult patient with no significant past medical history presenting with a cyst on the spleen?

Management of Incidental Splenic Cyst in an Adult

For an asymptomatic adult with an incidentally discovered splenic cyst and no trauma history, observation with imaging surveillance is the appropriate initial approach, reserving intervention for cysts >5 cm, symptomatic lesions, or when complications develop. 1, 2

Initial Diagnostic Approach

Obtain contrast-enhanced CT scan to characterize the cyst, as this is the gold standard imaging modality with 96-100% sensitivity and specificity for splenic lesions. 3 The CT should assess:

• Cyst size, location, and relationship to splenic hilum and major vessels 4
• Presence of internal septations, debris, or solid components 2
• Wall characteristics (thin vs. thick, calcifications) 1
• Evidence of complications (hemorrhage, rupture, infection) 1, 5

Doppler ultrasound or contrast-enhanced ultrasound can supplement CT for evaluating vascular anatomy and monitoring during follow-up. 3

Classification and Risk Stratification

Splenic cysts are divided into:

• Primary (true) cysts: Have epithelial lining; include congenital epidermoid, dermoid, or parasitic (Echinococcus) types 4, 5
• Secondary (pseudocysts): Lack epithelial lining; typically post-traumatic, hemorrhagic, or degenerative 5

The distinction matters less for management than cyst size, symptoms, and complication risk. 1

Management Algorithm

For Cysts <5 cm and Asymptomatic:

Conservative management with serial imaging surveillance is appropriate. 1, 2

• Repeat imaging at 3-6 months initially, then annually if stable 2
• Patient education about warning signs: acute abdominal pain, left upper quadrant fullness, fever (suggesting rupture, hemorrhage, or infection) 1, 5

For Cysts ≥5 cm or Symptomatic:

Surgical intervention is recommended due to rupture risk and potential complications. 1, 2, 4

Laparoscopic spleen-preserving surgery is the preferred approach when technically feasible:

• Laparoscopic partial cystectomy (decapsulation) for cysts with favorable anatomy 2, 4
• Laparoscopic cystectomy for peripherally located cysts away from hilum 4
• Avoid laparoscopic splenectomy in trauma settings with active bleeding, but it is appropriate for elective management of benign cysts 3, 2

When Total Splenectomy is Required:

Reserve splenectomy exclusively for cases where preservation is not technically possible: 6

• Multiple complex cysts without favorable window for preservation 6
• Cysts involving hilum with high bleeding risk 6, 4
• Post-operative splenic ischemia after attempted preservation 6, 4
• Giant cysts (>20 cm) where preservation is anatomically impossible 1

Critical Post-Splenectomy Management

If total splenectomy is performed, lifelong vaccination and antibiotic prophylaxis are mandatory to prevent overwhelming post-splenectomy infection (OPSI). 6

Vaccination protocol (start ≥14 days post-operatively or before discharge if early discharge planned): 3, 6

• Pneumococcal vaccination (S. pneumoniae) 3, 6
• Meningococcal vaccination (N. meningitidis) 3, 6
• Haemophilus influenzae type B vaccination 3, 6
• Annual influenza vaccination for patients >6 months 3

Antibiotic prophylaxis: 3, 6

• Lifelong prophylactic antibiotics should be strongly considered 3, 6
• Empiric antibiotics for any unexplained fever, malaise, or constitutional symptoms 3
• Primary care providers must be informed of splenectomy status 3

Special Considerations and Pitfalls

Common pitfalls to avoid:

• Underestimating rupture risk in large cysts (>10 cm): These carry significant risk of peritonitis and anaphylactic reactions if ruptured 1
• Omitting OPSI prevention protocols: This creates lifelong risk of fulminant infection 6
• Performing unnecessary splenectomy when preservation is feasible: Always attempt spleen-preserving techniques first 6, 2
• Premature intervention on small asymptomatic cysts: Conservative management is safe for cysts <5 cm 1, 2

For post-traumatic pseudocysts specifically, the same size and symptom criteria apply, though these may evolve over months to years after injury. 5

Activity restrictions after any splenic surgery: 4-6 weeks for minor procedures, up to 2-4 months for major interventions. 3