Incidental splenic lesion (an approach)

The majority of splenic lesions are benign and when an incidental splenic lesion is found in an asymptomatic patient, it may pose a dilemma in workup because imaging findings are often nonspecific.

• benign imaging features: no follow up
  • imperceptible wall
  • well-marginated
  • homogeneous
  • <10-20 HU
  • does not enhance after contrast
  • splenic hemangioma does not typically demonstrate peripheral nodular discontinuous enhancement
• not definitely benign features
  • prior imaging
    • unchanged over one year: no follow up
    • changed over the past year: MRI, PET, or biopsy follow up
  • no prior imaging
    • history of cancer
      • <1 cm: follow up MRI in 6 and 12 months
      • ≥1 cm: MRI, PET, or biopsy follow up
    • no history of cancer
      • indeterminate features: follow up MRI in 6 and 12 months
        • smooth margins
        • enhancement after contrast
        • >20 HU
        • heterogeneous
      • suspicious features: MRI, PET, or biopsy follow up
        • marked enlargement
        • splenic or vascular invasion
        • necrosis
        • irregular margins
        • enhancement after contrast
        • heterogeneous

Practical points

• even with a known malignancy, an incidental lesion <1 cm is thought to most likely represent a benign finding, although this is extrapolated from incidental hepatic lesion data
• primary splenic lymphoma is uncommon, look for other enlarged nodes before suggesting splenic lymphoma as a diagnosis
• splenic hemangiomas do not tend to enhance in a similar way to hepatic hemangiomas (peripheral nodular discontinuous enhancement) ²
• primary malignancy of the spleen is rare