Alena Levit MD Avice O Connell MD University of Rochester, Rochester, NY

Alena Levit MD Avice O Connell MD University of Rochester, Rochester, NY

Purpose Review imaging spectrum of both common benign and malignant breast lesions Describe and demonstrate CT features with mammogram, and in some instances, ultrasound and PET scan correlation in multiple cases of the common female and male breast conditions encountered while interpreting CT chest Provide a comprehensive approach to the CT interpretation of common breast conditions, which is valuable to both radiologists and clinicians Summarize diagnosis and treatment options, including pitfalls

Introduction Mammography is currently the gold standard in detection of breast cancer, however CT often provides the first images of the breast when scanning is performed for other diagnostic purposes and may be the first modality to demonstrate a new, potentially curable primary breast cancer Accurate assessment and description of breast lesions at CT includes characterization of the shape, margins, density, pattern of enhancement, and associated findings Any breast masses and calcifications with benign CT features require additional validation of benignity with either demonstration of long term stability and/or additional diagnostic workup, such as mammography and/or ultrasound

Female Breast Anatomy Adipose tissue (lobules of fat) Cooper s ligaments Mammary and periareolar ducts Lactiferous ducts Alveolar duct Nipple Glandular tissues (alveolar glands) Areola Inframammary fold

Benign Breast Conditions

2 cm or more of subareolar tissue in a non obese male, which may be unilateral or bilateral Fifbroblastic stroma 3 patterns: nodular, dendritic, and diffuse Ultrasound: Hypoechoic mass with lobulation or even spiculation 1 Pitfalls: Mimics breast cancer on ultrasound. Note that breast cancer is firmer on palpation Treatment: May eliminate offending agent and/or treat underlining disorder Rarely surgery may be performed in symptomatic patients Gynecomastia Male benign condition, characterized by hyperplasia of ductal and stromal elements Commonly seen in neonates, adolescents during puberty, and elderly men Causative etiologies: idiopathic, drug use (e.g. marijuana, cimetidine, omeprazole, or spironolactone), and hormonal stimulation, either exogenous or endogenous

Circumscribed fluid or soft tissue attenuation mass Cysts appear as asymmetries or masses Ultrasound: Anechoic mass with posterior acoustic enhancement and thin, imperceptible walls 2 Treatment Aspiration if patient is symptomatic Simple Cyst Common breast mass in women over age 35 Benign and not associated with an increased risk of breast cancer Most are asymptomatic; if symptomatic patients present with pain correlating to menstrual cycles

Circumscribed, round/oval mass that may demonstrate coarse popcornlike calcifications Well-defined round/oval mass of high density Ultrasound: Hypoechoic, wider-thantaller, and smoothly lobulated 3 Treatment: May regress Usually do not require intervention but surgery may be performed in some cases Fibroadenoma Most common benign solid breast tumor that occurs in reproductive period. It is frequently multiple and sometimes bilateral Usually regresses after menopause. Stromal tissue often hyalinizes densely and calcifies, and becomes a degenerating, calcifying fibroadenoma

Circumscribed, mixeddensity lesion that contains macroscopic far Well-circumscribed, round/oval mass containing both fat and soft-tissue density with a thin, radiopaque pseudocapsule Ultrasound: Sharply defined, heterogeneous oval mass or it may manifest as normal glandular tissue 4 Pitfalls: May manifest as a predominantly soft-tissue density Treatment: Follow-up or surgical excision Hamartoma (Fibroadenolipoma) Uncommon benign tumor that contains fat and glandular tissue surrounded by a thin capsule of connective tissue ( breast within the breast ) Usually occur in women > 35 years of age May be occult, but may manifest as a large, mobile, soft to firm mass

Mass with attenuation approximating that of skeletal muscle, may or may not contain phleboliths Circumscribed oval or lobular mass with punctate calcifications Ultrasound: Hypoechoic mass with posterior acoustic enhancement and variable Doppler flow 5 Treatment: Surgical excision Breast Hemangioma Benign vascular tumors of two common types (capillary and cavernous) that are based on the size of the vessels involved Can contain calcifications, including phloboliths May bleed during diagnostic core biopsy

Diffuse enlargement of glands and bilateral cord-and mass like hyperattenuating tissue Marked diffuse increase in density due to enlargement of the nonfatty fibroglandular component Ultrasound: The parenchyma is diffusely hyperechoic, in contrast to hypoechoic parenchyma seen in pregnancy. Increased vascularity and prominent ductal system is also seen 6 Pitfalls: Carcinoma may be obscured on mammogram due to diffuse increase in density. US is the most appropriate evaluation None Treatment: Lactating Breast Breast changes start in the 2 nd month of 1 st trimester of pregnancy Initial changes: marked ductular sprouting, simultaneous involution of the fibrofatty stroma, and an increase in glandular vascularity 2 nd and 3 rd trimester changes: marked lobular growth accompanied by a relative stromal decrease Lactating breasts show marked distention of lobular glands and accumulation of secretion in ducts

Nearly all calcifications seen on CT are benign, on the basis of size alone Lucent-centered calcifications, eggshell or rim calcifications, coarse or popcornlike calcifications, large rodlike, and round calcifications 7 Pitfalls: As spatial resolution of CT improves, microcalcifications may become apparent, therefore any suspicious calcifications require a follow up with mammography Benign Calcifications Commonly seen in breast tissue Typically benign calcifications: lucent-centered calcifications, eggshell or rim calcifications, coarse or popcornlike calcifications, large rodlike, and round calcifications

Malignant Breast Abnormalities

Dense spiculated mass with marked early and/or peripheral enhancement Dense, spiculated mass, which may contain pleomorphic calcifications Ultrasound: Solid hypoechoic mass with an irregular shape and spiculated or microlobulated margin, which may produce acoustic shadowing 8 Treatment: Surgical excision and additional (adjuvant) therapy Invasive Ductal Carcinoma-IDC Most common breast cancer, accounting for about 80% of all breast cancer diagnoses Most common in women > 55 years of age, although may occur at any age. It can also affect men.

Asymmetric soft-tissue density with or without associated skin thickening or mass with ill defined margins Mass with spiculated or illdefined margins or architectural distortion Ultrasound: Irregular or angular mass with hypoechoic and heterogeneous internal echoes, ill-defined or spiculated margins, and posterior acoustic shadowing 9 Pitfalls: Can be mammographically occult Treatment: Surgical excision and additional (adjuvant) therapy Invasive Lobular Carcinoma-ILC Second most common histologic type of breast carcinoma Associated with a higher rate of multiplicity and bilaterality The overall survival rate for patients with ILC of a given size and stage is believed to be slightly higher than for patients with the usual type invasive ductal carcinomas

Appears very similar to invasive ductal cancer Mass with indistinct borders Large, round lymph nodes in the axilla with loss of fatty hila May be multifocal Ultrasound: Hypoechoic hypervascular mass Marginal zone lymphoma 10 Lymphoma Pitfalls: Ill-defined mass that resembles invasive ductal cancer at mammography Secondary (manifestation of lymphoma elsewhere in the body) is more common than primary, although both are rare These tumors have no radiologic pathognomic features to distinguish them from breast adenocarcinoma Lymphadenopathy is the most common manifestation of secondary lymphoma

Lymphoma (peripheral T cell lymphoma) Peripheral T-cell lymphoma (PTCL) represents a relatively small proportion of lymphomas and has a lower prevalence in Western countries PTCL involves various organs including the sinonasal cavity, airway, intestinal tract, skin, lymph nodes, liver, lung, and musculoskeletal system

Discrete mass is often absent. Marked skin thickening and peripheral enhancement are seen Breast mass, asymmetric focal density, breast edema, microcalcifications, nipple retraction, or axillary adenopathy Ultrasound: Hypoechoic shadowing mass, breast edema, dilated lymphatic channels, and pectoral muscle invasion 11 Pitfalls: May mimic mastitis and abscess but will not respond to antibiotics Treatment: Chemotherapy before surgery or radiation therapy Inflammatory Carcinoma Uncommon tumor with dermal lymphatic invasion Frequently presents with increased warmth of skin, +/- erythema, induration of breast skin, and nipple retraction

Circumscribed soft tissue density masses Often found in the subcutaneous fat, in contrast, primary breast cancers are found in the glandular tissue Round masses with circumscribed or ill-defined borders More likely to be multiple or bilateral 12 Ultrasound: Masses with circumscribed margins and with low-level internal echoes Metastatic melanoma Metastases to the Breast Breast metastases from nonmammary primary tumors are uncommon At palpation, metastases feel similar is size to their appearance on mammography; in contrast, primary breast cancers tend to feel larger than their mammographic appearance Usually do not cause retraction of the skin or nipple Most common are: melanoma, non-hodgkin lymphoma, sarcoma, and carcinoma of the lung, stomach, prostate

Postoperative Findings

Irregular soft-tissue density mass, that changes to serous fluid as hematoma resolves Seroma: well-defined fluid collection, which may be associated with clips, calcifications, or air-fluid levels, and may enhance after contrast administration High density, usually circumscribed mass with illdefined margins 13 Ultrasound: Complex mass with internal echoes Pitfalls: Hematoma may be obscured by surrounding edema in the immediate postoperative period Abscess may have a similar appearance at CT Hematoma/Seroma May be caused by surgery, trauma, or biopsy, therefore correlation with clinical history is imperative Hematoma will become smaller over time, in contrast, mass will either remain the same or increase in size over time

Most commonly seen as spiculated dense mass Area of architectural distortion Irregular, spiculated, high density mass Ultrasound: Irregular hypoechoic mass with acoustic shadowing 14 Pitfalls: Appearance of postsurgical scar may mimic primary breast cancer Fibrous Scar As scar, develops, air and fluid are absorbed and the surrounding glandular tissue is drawn to a central nidus of fibrous tissue Correlation with mammographic images, surgical history, biopsy sites, pathology findings, and clinical breast examinations are important for accurate differentiation Masses not corresponding to a postbiopsy scar should be further evaluated

Breast CT Lexicon A. Mass: space-occupying lesion seen in two different projections 1. Shape a. Round: spherical, ball-shaped, circular or globular b. Oval: elliptical or egg-shaped c. Lobular: mass with indulating contour d. Irregular: shape can not be characterized by any of the above 2. Margin: Modifies the shape of the mass a. Circumscribed (well-defined or sharply defined): at least 75% of the margin must be well defined, with the remainder no worse than obscured by overlying tissue b. Microlobulated c. Obscured: margin is hidden by superimposed or adjacent normal tissue d. Indistinct (ill-defined) margin: poor definition of the margin or any portion of the margin raises concern that there may be infiltration by the lesion and the appearance is not likely due to superimposed normal breast tissue e. Spiculated: characterized by lines radiating from the margin of a mass

Breast CT Lexicon 3. Density (in Hounsfield units): a. Fat b. Air c. Fluid d. Soft tissue 4. Enhancement pattern (if contrast material administered) a. Homogenous b. Heterogeneous c. Rim enhancing d. Central enhancement e. Enhancing internal septations 5. Associated findings a. Edema b. Skin/Nipple retraction c. Skin thickening d. Lymphadenopathy e. Chest wall or skin invasion f. Presence of hematoma or blood g. Architectural distortion

Breast CT Lexicon B. Calcifications-Benign a. Lucent-centered b. Eggshell or rim calcifications c. Coarse or popcornlike calcifications d. Large rodlike calcifications e. Round calcifications CT may be very sensitive for the detection of calcifications but small clusters of malignant microcalcifications (0.1 to 0.5 mm) are usually not seen. Nearly all calcifications that are seen on CT are benign, on the basis of size alone.

Conclusion Mammography is currently the gold standard in detection of breast cancer, however CT often provides the first images of the breast when scanning is performed for other diagnostic purposes Frequently, incidental breast lesions, which are not an uncommon finding on chest CT, are either overlooked or inaccurately assessed The aim of this exhibit was to expose the general radiologist to the range of breast abnormalities that may be encountered on CT chest and their imaging characteristics in addition to the comprehensive approach of interpreting these lesions It is important that the breast tissue is not overlooked on chest CT and that the breast abnormalities are recognized and accurately characterized as benign, malignant, or sufficiently suspicious to necessitate further workup

References 1. Boone JM, Nelson TR, Lindfors KK, et al. Dedicated breast radiation dose and image quality evaluation. Radiology 2001; 221:657 667. 2. Breast imaging reporting and data system: mammography. 4th ed. Reston, Va: American College of Radiology, 2003. 3. Goldberg PA, White CS, McAvoy MA, et al. CT appearance of the normal and abnormal breast with mammographic correlation. Clin Imaging 1994;18:262 272. 4. Ikeda DM. Breast imaging: the requisites. Philadelphia, Pa: Elsevier Mosby, 2004. 5. Kim SM, Park JM. Computed tomography of the breast: abnormal findings with mammographic and sonographic correlation. J Comput Assist Tomogr 2003; 27:761 770. 6. Lopez JK, Bassett LW. Invasive Lobular Carcinoma of the Breast: Spectrum of Mammographic, US, and MR Imaging Findings. RadioGraphics 2009; 29 (1):165-176. 7. Marsteller LP, Shaw de Paredes E. Well defined masses in the breast. RadioGraphics 1989; 9(1):13 37. 8. Sabate JM, Clotet M, Torrubia S, Gomez A, Guerrero R, Heras PdL, Lerma E. Radiologic Evaluation of Breast Disorders Related to Pregnancy and Lactation. RadioGraphics 2007; 27:S101 S124.