Can a filling defect on imaging be associated with cancer?

Can a Filling Defect Be Associated with Cancer?

Yes, filling defects on imaging can definitely be associated with cancer, though the specific cancer risk depends heavily on the anatomic location and imaging characteristics of the defect.

Breast Duct Filling Defects (Ductography)

Intraductal filling defects on ductography are suggestive of malignant or papillary lesions and warrant further evaluation. 1

Key Imaging Features Suggesting Malignancy:

• Intraductal filling defect (the most direct sign) 1
• Partial or complete duct obstruction 1
• Duct expansion or distortion 1
• Duct wall irregularity 1

Performance Characteristics:

• For detecting cancer in pathologic nipple discharge, ductography demonstrates sensitivity of 75-100% but specificity of only 6-49% 1
• Positive predictive value for cancer and high-risk lesions is 19% 1
• Critical limitation: False-negative rate can be as high as 20-30%, meaning a negative ductogram does not exclude cancer 1

Clinical Context:

• The primary value of ductography is not to determine if surgery is needed, but rather to localize the precise site of intraductal lesions to guide surgical approach 1
• When standard mammography and ultrasound are negative, ductography can localize 76% of otherwise occult malignant/high-risk lesions 1

Ureteral Filling Defects

Filling defects in the ureter are strongly associated with transitional cell carcinoma, with the pattern predicting invasiveness. 2

Pattern-Based Risk Stratification:

• Infiltrating and plaque-like patterns: Significantly associated with advanced disease (odds ratio 6.75) compared to ovoid and polypoid patterns 2
• These aggressive patterns suggest deeper invasion and worse prognosis 2
• The filling defect pattern provides important preoperative information for treatment planning 2

Colonic Filling Defects

While many colonic filling defects are benign (stool, polyps), some represent malignancy and require differentiation. 3

• CT colonography can detect numerous filling defects, requiring correlation with morphologic and attenuation characteristics to distinguish benign from malignant lesions 3
• Lesions may be indeterminate and require endoscopic evaluation when imaging features overlap 3

Important Caveats and Pitfalls:

Avoid Over-Reliance on Single Modality:

• Never use ductography findings alone to determine malignancy—the low specificity (6-49%) means many benign lesions will appear suspicious 1
• Always correlate filling defects with complementary imaging (mammography, ultrasound, MRI) and clinical context 1

False-Positive Considerations:

• Not all filling defects represent cancer—benign causes include papillomas, blood clots, inspissated secretions, and inflammatory changes 1
• In the colon, stool and benign polyps commonly create filling defects 3

False-Negative Risk:

• A normal study does not exclude cancer—the 20-30% false-negative rate for ductography is clinically significant 1
• If clinical suspicion remains high despite negative imaging, proceed to tissue diagnosis 4

Context-Dependent Interpretation:

• The cancer association varies dramatically by anatomic site—breast duct filling defects have different implications than ureteral or colonic defects 1, 2
• Patient age, symptoms (spontaneous bloody discharge vs. clear discharge), and risk factors modify the pre-test probability 4

Bottom line: Filling defects should trigger a systematic evaluation based on location and characteristics, with tissue diagnosis often required for definitive management, particularly when imaging features suggest malignancy or clinical suspicion remains high.