Etymology: Derived from the Greek word “splen,” meaning spleen, and the suffix “-osis,” indicating a pathological condition or process.
AKA:
- Autotransplanted splenic tissue
What is it? Splenosis is the heterotopic autotransplantation of splenic tissue following trauma or splenectomy, where fragments of the spleen seed various locations, most commonly the peritoneal cavity, and develop into functional splenic nodules.
Caused by:
- Splenic trauma (most common)
- Splenectomy
Resulting in:
- Multiple soft tissue nodules of splenic tissue distributed within the abdomen or thorax
- May retain partial immunological function
Structural changes:
- Formation of multiple small, soft tissue nodules composed of splenic tissue
- Typically well-circumscribed and non-calcified
Pathophysiology: After splenic rupture, viable splenic fragments seed the peritoneal cavity. If the fragments revascularize and receive adequate perfusion, they can develop into functioning splenic nodules.
Pathology:
- Histologically composed of normal splenic tissue
- Contains red pulp, white pulp, and vascular sinusoids
Diagnosis:
- Often incidentally found on imaging
- Confirmed with nuclear medicine scans
Clinical:
- Usually asymptomatic
- May present with complications such as small bowel obstruction or mimic malignancy
Radiology:
- Characteristic imaging findings include multiple, well-circumscribed soft tissue nodules
- Can resemble peritoneal carcinomatosis
Labs:
- Normal unless complications arise
- Functional splenosis may provide partial immune protection
Management:
- Often conservative
- Symptomatic cases or diagnostic uncertainty may require biopsy or nuclear imaging
Radiology Detail:
Abdominal Plain Film (KUB):
- Findings: Non-specific soft tissue nodules
- Associated Findings: Dilated bowel loops if bowel obstruction occurs
CT:
- Parts: Abdomen, pelvis
- Size: Variable, typically 1-3 cm nodules
- Shape: Round to oval
- Position: Scattered throughout the peritoneal cavity
- Character: Homogeneous soft tissue density
- Time: Chronic
- Associated Findings: Prior splenic trauma or splenectomy
Other relevant Imaging Modalities:
- Nuclear Medicine (Tc-99m sulfur colloid scan): Gold standard for confirming functional splenic tissue
- MRI: Can demonstrate soft tissue masses with similar signal intensity to the spleen
Pulmonary function tests (PFTs):
- Not applicable
Recommendations:
- If functional splenic tissue is confirmed, pneumococcal vaccination may not be required
- Imaging follow-up only if symptomatic
Key Points and Pearls:
- Splenosis occurs due to autotransplantation of splenic tissue following trauma or splenectomy
- Functional splenic tissue may offer partial immunologic protection
- Tc-99m sulfur colloid scans are the preferred imaging modality for confirmation
Comment: Splenosis is the heterotopic autotransplantation of splenic tissue following trauma or splenectomy, typically presenting as multiple peritoneal nodules that can be confirmed with Tc-99m sulfur colloid scans.