1. What breast lesions do we find incidentally on CT?
David Salgado PGY-1 Radiology
Karim Virani PGY-3 Radiology
Siam Iles FRCPC Radiologist and Associate Professor

2. Disclosures
None

3. Outline
Anatomy
Malignant lesions
Benign lesions

4. Pectoralis major
Fibroglandular tissue
Retromammary space

5. Malignant lesions DCIS Ductal carcinoma in situ (DCIS)
Invasive ductal carcinoma
Invasive lobular carcinoma
Inflammatory carcinoma
Lymphoma
Metastasis
Lung Cancer, Melanoma, Chondrosarcoma
DCIS

6. Breast cancer Lifetime risk of breast ca = approximately 12%
Incidental breast lesions:
89/8105 CT’s (1.1%) (Surov et al., 2012)
31/2945 CT’s (1.1%) (Monzawa et al., 2013)
Malignant findings in 0.4%  ~1 in 250 chest CT’s

7. DCIS Not commonly detected on CT
Typically has segmental nonmasslike enhancement

8. Invasive ductal carcinoma
Most common breast cancer (80-90% of all invasive ca)
CT: dense, spiculated, early/peripheral enhancement
Advanced: skin thickening, lymphadenopathy, pleural effusions, osseous metastases

9. Invasive ductal carcinoma

10. Invasive lobular carcinoma
10-15% of all invasive breast cancer
Diffuse parenchymal infiltration
Subtle mammographic findings
Discrete mass less common
Microcalcifications rare
Nonspecific CT findings

11. Invasive lobular carcinoma

12. Inflammatory carcinoma
Uncommon, aggressive
Early dermal lymphatic invasion
Occasionally similar to mastitis/abscess
No response to antibiotics
CT: skin thickening, peripheral enhancement, focal mass or nodule

13. Inflammatory carcinoma

14. Lymphoma DLBCL Secondary>primary Usually Non-Hodgkins
Lymphadenopathy (esp. axillary)
DLBCL

15. Metastasis Lung cancer metastasis
Most common: contralateral breast ca, sarcomas, lymphomas
Others: melanoma, lung, chondrosarcoma, carcinoid, gastric, renal, etc.
Met vs. primary on CT
Multiple, bilateral, superficial
Lung cancer metastasis

16. Contralateral lymph node involvement

17. Chondrosarcoma

18. Melanoma

19. Malignant versus benign
Irregular margins
Irregular shape
Rim enhancement
Greater than 1 cm
Washout pattern
High PPV, low NPV (Sardanelli et al., 1998)
Poyraz, 2015
Inoue et al., 2003

20. Benign breast lesions Fibroadenomas Fibrocystic changes
Benign calcification
Macrocalcification only
No microcalcifications detected
Gynecomastia
Neurofibromatosis
Neurofibromatosis

21. Fibroadenoma Most common benign breast lesion Age 15-40
Proliferation of connective tissue
CT: circumscribed, rounded, +/- popcorn calcifications
FA without calcification can look like cancer

22. Fibrocystic changes CT can demonstrate a well circumscribed mass
U/S is recommended and shows a hypoechoic solid round nodule

23. Gynecomastia Biopsy: Chronic inflammation Gynecomastia normal tissue
Most common abnormality of the male breast
Proliferation of ductal/stromal tissue
Various causes:
Endogenous hormones
Cirrhosis
Renal disease
Hyperthyroidism
Medication
Subareolar soft tissue density
Biopsy: Chronic inflammation
Gynecomastia normal tissue

24. Benign calcifications
Round/oval = benign
CT = macrocalcification = benign (usually)

25. Conclusion
Always review the four quadrants of the breast and the axilla on CT
~1/250
Characterize breast lesions
All benign appearing lesions should be confirmed by repeat imaging or mammo/US/biopsy

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