What are the mammogram signs of malignancy?

Mammographic Signs of Breast Malignancy

The key mammographic features highly suggestive of malignancy include spiculated masses, pleomorphic microcalcifications in linear or segmental distribution, architectural distortion, and irregular masses with ill-defined margins. 1

Primary Mammographic Signs of Malignancy

Mass Characteristics

• Irregular shape: Non-uniform or asymmetric masses
• Margins:
  • Spiculated (radiating lines extending from the mass)
  • Ill-defined or indistinct
  • Microlobulated
• Density: High density compared to surrounding breast tissue
• Size and growth: New or enlarging masses compared to prior mammograms

Calcification Patterns

• Morphology:
  • Fine pleomorphic (varying shapes and sizes)
  • Fine linear or branching (casting)
  • Amorphous or indistinct
• Distribution:
  • Linear arrangement (following a ductal pattern)
  • Segmental distribution
  • Grouped or clustered
  • Regional

Architectural Distortion

• Distortion of normal breast architecture without a visible mass
• Focal retraction or distortion of tissue
• Speculation radiating from a point

BI-RADS Classification System

The American College of Radiology's BI-RADS system provides standardized categorization of mammographic findings 1:

• Category 4: Suspicious abnormality - biopsy should be considered

  • Risk of malignancy varies but is greater than category 3 and less than category 5
  • Includes suspicious masses and calcification patterns

• Category 5: Highly suggestive of malignancy (≥95% likelihood)

  • Includes spiculated masses
  • Malignant-appearing pleomorphic calcifications
  • Classic malignant features requiring immediate action

Secondary Signs of Malignancy

• Asymmetry/Focal asymmetry: Asymmetric breast tissue without the borders or characteristics of a mass
• Skin thickening or retraction: May indicate underlying malignancy
• Nipple retraction: New or increasing retraction
• Axillary lymphadenopathy: Enlarged or abnormal-appearing lymph nodes

Specific Malignant Presentations

Ductal Carcinoma In Situ (DCIS)

• Fine, linear, discontinuous, and branching microcalcifications
• Linear, ductal, or segmental distribution
• May present as a mass, asymmetry, or architectural distortion in 12% of cases 1

Invasive Carcinoma

• Spiculated masses with or without associated calcifications
• Irregular margins and shape
• Architectural distortion
• High density on mammography 1

Diagnostic Performance

• Mammography for detecting malignancy has sensitivity between 15-68% and specificity between 38-98% 1
• Digital breast tomosynthesis (DBT) may improve detection of architectural distortion and subtle masses 1
• Ultrasound is complementary to mammography, particularly for dense breasts or when evaluating a palpable abnormality 1

Clinical Pitfalls

• False negatives can occur with:

  • Dense breast tissue obscuring lesions
  • Small lesions without calcifications
  • Completely intraductal lesions
  • Lesions in difficult locations (e.g., axillary tail)

• Benign conditions that may mimic malignancy:

  • Radial scars (may have radiolucent centers but can be difficult to differentiate from carcinoma) 2
  • Sclerosing adenosis (often has punctate calcifications and radiolucent centers) 2
  • Post-surgical scarring
  • Fat necrosis

Important Considerations

• Even with negative mammography, a suspicious physical examination should prompt biopsy 1
• The combination of mammography and ultrasound has a very high negative predictive value (>97%) 1
• Any circumscribed or cystic mass in male patients should be viewed with suspicion 1
• Careful evaluation of mass margins and morphologic features of calcifications is essential for distinguishing malignant from benign findings 3

Remember that while these signs are highly suggestive of malignancy, definitive diagnosis requires tissue sampling through biopsy.