Initial Triage

Benign appearance

• Simple cyst, accessory spleen, healed granulomatous calcification, or classic benign vascular lesion: usually no follow-up.
• Benign CT features include smooth margins, homogeneous low attenuation, no enhancement, and no aggressive behavior.
• If a lesion is unchanged for at least 1 year and there is no cancer history, it is generally treated as benign.

Nondiagnostic appearance

• Look for prior imaging first.
• If stable for at least 1 year: no further evaluation.
• If new, enlarging, or no prior comparison: choose follow-up MRI, PET, or biopsy based on cancer history and suspicious features.

Imaging Patterns

Cystic / benign

• Simple epithelial cyst: thin wall, fluid attenuation/signal, no enhancement.
• Pseudocyst: may have thick wall, calcification, or posttraumatic history.
• Accessory spleen: same enhancement and signal as spleen on every phase/sequence.

Solid vascular / multiple

• Hemangioma: progressive or persistent enhancement.
• Hamartoma: early arterial enhancement with delayed equilibration.
• SANT: fibrous rim/radiating bands or spoke-wheel enhancement pattern.
• Multiple lesions raise inflammatory, lymphoma, littoral cell angioma, or metastasis considerations.

Indeterminate / Suspicious

Escalate

• Suspicious features: heterogeneous enhancement, irregular margins, necrosis, vascular invasion, or rapid growth.
• Known cancer history: lower threshold for MRI, PET, or biopsy, especially for lesions 1 cm or larger.
• No cancer history with indeterminate features: MRI follow-up at about 6 and 12 months is a common pathway.

Symptoms

• Pain attributable to the spleen: consider surgical consultation; MRI if further characterization is needed.
• Systemic symptoms or splenomegaly: consider lymphoma, infection, sarcoid, inflammatory disease, metastasis, or angiosarcoma.
• Biopsy is reserved for cases where imaging remains indeterminate and tissue diagnosis will change management.

Sources

• ACR incidental spleen and nodes white paper
• CAR 2025 spleen and nodes recommendations
• WFUMB spleen incidental findings position paper
• Integrated imaging and pattern approach review