Solid Breast Nodules: Benign vs. Malignant

Introduction

• Speaker: Cindy Rath from University of Colorado Hospital
• Topic: Differentiating benign vs. malignant solid breast nodules

Types of Breast Cancer

• Invasive Ductal Carcinoma (most common)
• Invasive Lobular Carcinoma
• Medullary, Mucinous
• DCIS (Ductal Carcinoma In Situ)
• Metastasis

Approach to Finding Solid Lesions

1. Seek Malignant Findings
2. Classify as Benign
3. Indeterminate Lesions require biopsy

Heterogeneity of Breast Cancer

• Important to scan entire nodule in two planes
• Mixture of benign and malignant findings excludes benign classification

Growth Morphology

• Well-circumscribed (can be malignant)
• Radial scars (speculated lesions)
• Complex spectrum of growth

Diagnostic Accuracy with Ultrasound

• Multiple findings compared, similar to mammography
• False negative rate <2%
• Features of breast cancer: spiculation, angular margins, acoustic shadowing, taller than wide, etc.

Detailed Malignant Features

Spiculations

• Hard Finding: Hypoechoic or echogenic depending on background tissue
• Example: anterior surface spiculation, multifocal lesions

Angular Margins

• Related to invasive carcinoma
• High accuracy in diagnosing invasive lesions

Micro-lobulation

• Soft Finding: Associated with either invasion or DCIS
• Different presentations: invasive tumor fingers, cancerizing lobules, etc.

Taller than Wide

• Malignant Indicator: Often seen in small nodules
• Axis orientation related to growth in terminal ductal lobular unit (TDLU)
• More common in smaller nodules (<10mm) than larger (>20mm)

Duct Extension and Branch Pattern

• Duct extension: growing back towards the nipple
• Branch pattern: growing away from nipple
• Soft Findings: Often indicative of DCIS

Acoustic Shadowing

• Hard Finding: Related to invasive carcinomas
• Related to desmoplastic reaction
• Low-grade ductal cancers shadow, high-grade may enhance through transmission

Calcifications

• Soft Finding: Associated with DCIS
• Often need correlation with mammogram for associated mass

Markedly Hypoechoic

• Indicator: Modern equipment reduces marked hypo-echogenicity detection
• Effect of dynamic range on image clarity/contrast

Benign Features

Purely Hyperechoic Tissue

• May be normal fibro-glandular tissue or area of fibrosis
• Must rule out mass within hyperechoic region

Elliptical Shape

• Up to 2-3 gentle lobulations allowed
• Must have thin echogenic pseudo-capsule

Additional Considerations

• Light scanning pressure can reveal thin capsule
• Avoid assuming capsule means benign without further checks

Lymph Node Assessment

Normal and Abnormal Characteristics

• Normal: Cortex, echogenic lymphatic portion, fatty hilum
• Abnormal: Thick cortex, displaced fatty hilum, grossly abnormal nodes indicate malignancy

Lymph Node Flow

• Lymphatic flow from outer node inwards
• Tumor metastasis affects cortex first; opposite for foreign body involvement

Diagnostic Approach

• Multiple abnormal nodes suggest inflammatory process
• Single abnormal next to normal node suggests malignancy
• Biopsied nodes may impact surgical decisions

Conclusion

• Understand the detailed features and approach when identifying solid breast nodules
• Accurate diagnostics crucial for patient outcomes