Understanding Your Imaging Findings
These imaging findings describe three separate liver and gallbladder conditions that are commonly seen together and generally benign, but the gallbladder polyp requires size-based risk stratification and potential follow-up according to established guidelines.
What Each Finding Means
Focal Fatty Infiltration of the Liver
This refers to localized areas where fat has accumulated in liver tissue, while surrounding liver remains relatively normal. Focal fatty infiltration is a benign finding that does not increase mortality or affect quality of life 1, 2.
- Common locations: Most frequently occurs around the gallbladder fossa (segments 4 and 5 of the liver) 1
- Mechanism: Related to aberrant blood flow patterns, particularly from gallbladder vessels that alter local fat distribution 3, 1
- Clinical significance: This is NOT a tumor or malignancy—it's simply uneven fat distribution in the liver
- Association: Fatty liver itself is independently associated with gallbladder polyps 4
Key point: When focal fatty sparing (the reverse pattern) appears around the gallbladder, it occurs in 67-78% of patients with fatty liver who have an intact gallbladder, but only 33% after cholecystectomy 1. This confirms the gallbladder's blood supply influences local liver fat patterns.
Probable Gallbladder Polyp
A gallbladder polyp is defined as a solid, non-mobile, non-shadowing protrusion from the gallbladder wall 5.
Management depends entirely on polyp size 5:
If polyp is ≤5 mm:
- No follow-up required if you have no risk factors 6
- Zero documented cases of malignancy at this size in multiple large studies 5
- Up to 83% of apparent 5mm polyps are not found at subsequent surgery (often adherent debris) 5
If polyp is 6-9 mm:
- Without risk factors: Ultrasound follow-up at 6 months, 1 year, and 2 years 6
- With risk factors: Consider cholecystectomy 6
- Risk factors include: age >60 years, primary sclerosing cholangitis, Asian ethnicity, sessile (broad-based) shape, or focal wall thickening >4mm 6
If polyp is 10-14 mm:
- Surgical consultation recommended based on patient factors or growth 5
- Malignancy risk increases but remains low (8.7 per 100,000 patients) 5
If polyp is ≥15 mm:
- Cholecystectomy strongly recommended if surgically fit 5, 6
- Size ≥15mm is an independent predictor of neoplastic polyps 5
Non-mobile Stone Not Excluded
This phrase indicates the radiologist cannot definitively distinguish between:
- A true gallbladder polyp (attached to the wall)
- An adherent gallstone (stuck to the wall but not a true polyp)
- Tumefactive sludge (coalesced bile that mimics a mass) 5
Next step if unclear 5:
- Repeat ultrasound in 1-2 months with optimized technique (patient fasting, proper positioning, color Doppler)
- If still uncertain and lesion is ≥10mm: Consider contrast-enhanced ultrasound (CEUS) or MRI for characterization
- True polyps show internal vascularity on Doppler; stones and sludge do not 5
Recommended Action Plan
Step 1: Determine the exact size of the "probable polyp" from your imaging report
Step 2: Apply the size-based algorithm above
Step 3: If the report doesn't specify size or characterization is uncertain:
- Request repeat ultrasound with optimized technique in 1-2 months
- Ensure you're fasting 6-8 hours before the exam
- Request color Doppler imaging to assess vascularity
Step 4: Assess your risk factors (age >60, PSC history, Asian ethnicity)
Common Pitfalls to Avoid
- Don't assume all gallbladder wall lesions are polyps: Many are adherent stones or sludge that resolve on repeat imaging 5
- Don't over-surveil tiny polyps: Polyps ≤5mm without risk factors need no follow-up 6
- Don't ignore growth: Any growth of ≥2mm during surveillance warrants reassessment 6
- Don't confuse focal fatty infiltration with a liver mass: This is a benign metabolic finding, not a tumor 7, 8
Bottom Line
The focal fatty infiltration is benign and requires no specific action. The gallbladder findings require size determination—if the polyp is ≤5mm, no follow-up is needed; if 6-9mm, surveillance ultrasound is appropriate; if ≥10mm, surgical consultation should be considered 5, 6. The uncertainty about whether this is a polyp versus stone necessitates either repeat optimized ultrasound or advanced imaging if the lesion measures ≥10mm 5.