Cystic Masses of the Breast

Transcription

1 Residents Section Pattern of the Month Eisenberg ystic Masses of the reast Residents Section Pattern of the Month Residents inradiology Neely Hines 1 Priscilla J. Slanetz Ronald L. Eisenberg Hines N, Slanetz PJ, Eisenberg RL Keywords: breast, cyst, cystic masses, lesions OI: /JR Received September 18, 2009; accepted after revision ecember 2, ll authors: epartment of Radiology, eth Israel eaconess Medical enter and Harvard Medical School, 330 rookline ve., oston, M ddress correspondence to R. L. Eisenberg (rleisenb@bidmc.harvard.edu). WE This is a Web exclusive article. JR 2010; 194:W122 W X/10/1942 W122 merican Roentgen Ray Society ystic Masses of the reast ystic lesions of the breast may present in women of any age but are most common between 30 and 50 years of age (Table 1). They may be detected incidentally on screening mammography or present with such signs and symptoms as nipple discharge or a palpable mass. On mammography, a cystic lesion appears as a round, oval, or lobulated mass with circumscribed margins (Figs. 1 and 1). However, the margins may become obscured due to pericystic fibrosis. ecause a cyst cannot be reliably diagnosed with mammography TLE 1: ifferential iagnosis of ystic reast Lesions Simple cyst omplicated or complex cyst Galactocele Hematoma Fat necrosis or oil cyst Mastitis or breast abscess Intracystic papilloma Necrotizing neoplasm TLE 2: reast Ultrasound Lexicon Summary of Terminology ackground echotexture Masses Vascularity Miscellaneous alone, further evaluation with spot-compression mammographic views and ultrasound (Figs. 1 and 1) is necessary. The compression views allow improved assessment of lesion morphology with respect to shape, margins, and associated findings such as calcifications or distortion. In addition, for lesions initially visualized on one mammographic projection, additional imaging at different angles or positions can permit localization three dimensionally in the breast leading to targeted ultrasound. Ultra- Homogeneous, fat Homogeneous, fibroglandular Heterogeneous Shape: oval, round, irregular Orientation: parallel, antiparallel Margin: circumscribed, not circumscribed (indistinct, angular, microlobulated, spiculated) Lesion boundary: abrupt interface, echogenic halo Echo pattern: anechoic, hyperechoic, complex, hypoechoic, isoechoic Posterior acoustic features: none, enhancement, shadowing, combined pattern Surrounding tissue: ducts, changes in ooper s ligaments, edema, architectural distortion, skin thickening, skin retraction Present or not present, adjacent to lesion, diffusely increased lustered microcysts, complicated cysts, mass in or on skin, foreign body, intramammary or axillary lymph nodes W122 JR:194, February 2010

2 ystic Masses of the reast TLE 3: I-RS ssessment ategories [9] I-RS ategory ssessment Recommendation 0 Incomplete examination dditional imaging necessary 1 Normal Yearly screening mammography 2 enign findings Yearly screening mammography 3 Probably benign, < 2% chance of malignancy Short-interval follow-up 4 Suspicious abnormality Take appropriate action 4: low probability 1 3% chance of malignancy iopsy or surgical excision 4: intermediate probability 3 50% chance of malignancy 4: high probability 51 94% chance of malignancy 5 Suspicious abnormality, > 95% chance of malignancy Take appropriate action, biopsy or surgical excision 6 iopsy-proven malignancy Take appropriate action Fig. 1 Palpable left breast mass. and, Mammography images confirm circumscribed dense mass in lower inner left breast. and, Ultrasound images show complex cystic lesion with vascular thick septations. iopsy revealed grade I intracystic papillary carcinoma. JR:194, February 2010 W123

3 Eisenberg sound permits characterization of the mammographic mass because it can reliably differentiate cystic from solid lesions in most cases. ssessment of a mass seen on ultrasound includes evaluation of the lesion s shape, orientation, margin, boundary, internal echotexture, posterior acoustic features, surrounding tissue, calcifications, and vascularity. cceptable descriptive terms for each of these features and the assessment categories according to the merican ollege of Radiology breast ultrasound lexicon are summarized in Tables 2 and 3, respectively. When the lesion does not meet all criteria for a simple cyst (discussed next), imaging-guided intervention, including aspiration or core biopsy, is often necessary to exclude a solid mass. Simple ysts Simple cysts are the most common masses seen at mammography and result from dilatation and effacement of the terminal duct lobular unit (Figs. 2 2). Mammographic imaging typi- Fig. 2 Simple cyst. and, raniocaudal () and mediolateral oblique () mammographic images show circumscribed oval mass in upper outer quadrant of left breast., Spot-compression craniocaudal image confirms circumscribed margins., Ultrasound image obtained same day shows cm oval anechoic mass with increased through transmission and imperceptible wall, consistent with simple cyst. (Fig. 2 continues on next page) W124 JR:194, February 2010

4 ystic Masses of the reast E Fig. 2 (continued) Simple cyst. E and F, MR images show cyst follows fluid signal and appears slightly hypointense to breast parenchyma on T1-weighted image (E) and hyperintense on T2-weighted image (F). cally shows a circumscribed round or oval mass (Figs. 2 2). Ultrasound is used to confirm that the mammographic finding represents a cyst (Fig. 2). For a cyst to be classified as a simple cyst, it must satisfy all the sonographic criteria set forth by Stavros [1, 2]: anechoic, well circumscribed with a thin echogenic capsule, increased through-transmission, and thin edge shadows. ysts are frequently multiple and fluctuate in size on serial examinations. If multiple circumscribed, round or oval masses of varying sizes are seen at screening mammography, they likely represent cysts. In this case, ultrasound is usually not necessary, and the patient may continue with routine annual screening. However, some centers prefer imaging at 6-month intervals to document fluctuation. Once a mass meets all the criteria for a simple cyst, it is classified as I-RS 2 and the patient may return to a screening protocol. Simple cysts are commonly seen incidentally on MRI and follow fluid signal on all sequences (Figs. 2E and 2F). Therefore, they are iso- or hypointense to breast parenchyma on fat-suppressed T1-weighted images (Fig. 2E) and very hyperintense on T2-weighted images (Fig. 2F). Simple cysts do not enhance; however, the periphery of the cyst may enhance if there is surrounding pericystic inflammation. spiration may be performed if the patient is symptomatic or if the cyst prevents adequate compression for mammography. spirated fluid is typically not sent for cytology if it is cloudy yellow or green because of high false-positive rates. The fluid is sent for cytologic evaluation if it is bloody or if the patient requests that the aspirate be tested. The differential diagnosis for a simple cyst includes galactocele, hematoma, and oil cyst, all of which are reviewed in this article. F Fig. 3 omplicated cyst., Mediolateral oblique () and craniocaudal () images of left breast show round circumscribed mass in mid outer quadrant. (Fig. 3 continues on next page) JR:194, February 2010 W125

5 Eisenberg omplicated ysts cyst that meets all the criteria of a simple cyst (Figs. 3 and 3) except that it contains low-level internal echoes or fluid fluid or fluid debris levels that can shift with changes in the patient s position is considered a complicated cyst (Figs. 3 and 3). The causes of internal echoes within an otherwise simple cyst include cell debris, protein, cholesterol, blood, Ws, and epithelial cells. On MRI (Figs. 3E 3G), a complicated cyst may have intermediate or high signal on T1-weighted images because of proteinaceous contents or blood products. The appearance on T2-weighted images is variable depending on the cyst contents. ecause complicated cysts do not meet the criteria of a simple cyst, they cannot be given a I-RS 2 classification. Instead, a more appropriate classification is I-RS 3 because there is only a 0.2% chance of malignancy. spiration or short-interval follow-up should be Fig. 3 (continued) omplicated cyst. and, Ultrasound images obtained same day shows round hypoechoic mass with low-level internal echoes and no internal flow. E G, MR images show well-defined, round mass that corresponds to mammographic and sonographic findings. Mass shows characteristics of proteinaceous or hemorrhagic cyst, with low signal on T1-weighted image (E), high signal on unenhanced T2-weighted image (F), and minimal rim enhancement on subtracted image (G). E F G W126 JR:194, February 2010

6 ystic Masses of the reast offered. The differential diagnosis of a complicated cyst is the same as that of a simple cyst, with the addition of abscess (discussed later). omplex ysts cyst with thick walls or some discrete solid component, such as septa greater than 0.5 mm thick or mural nodules, is categorized as a complex cyst. These cysts can be further subdivided as cysts with nodular components and complex cysts. The differential diagnosis for a cyst with a mural nodule includes intracystic papilloma, atypical ductal hyperplasia, ductal carcinoma in situ, and papillary carcinoma. The differential diagnosis for a complex cyst includes hematoma, fat necrosis, abscess, galactocele, and necrotic neoplasm. ifferential iagnostic onsiderations Galactocele galactocele forms from the accumulation of milk distal to an obstruction in the terminal ductal unit. The age of the milk products contained in the galactocele determines its mam- Fig. 4 Galactocele. and, Mediolateral oblique () and magnified lateral () mammographic images of left breast in lactating patient who presented with palpable lump show partially obscured circumscribed mass (), which on magnified image () has fat fluid level. and, Ultrasound images in transverse () and sagittal () planes show hypoechoic mass with low-level internal echoes and increased through transmission, consistent with complicated cyst. Given imaging appearance, findings are consistent with galactocele. Patient declined aspiration. JR:194, February 2010 W127

7 Eisenberg mographic and sonographic appearances. Mammographic images typically show a circumscribed oval or round mass. In the acute setting, a galactocele may appear as a complicated cyst or anechoic fluid with thin septa. s the galactocele ages, the cyst increases in complexity, developing echogenic foci due to separation of the fat components and fat fluid levels with the echogenic component layering in the nondependent portion (Fig. 4). Mammographically, this appears as a round or oval mass with fluid density dependently and fat density layering on top. Eventually the milk curdles, leading to the development of solid components within the cyst. Finally, the lesion may appear as a solid echogenic mass. Most galactoceles resolve with conservative management. When the diagnosis is uncertain, ultrasound-guided aspiration will confirm the diagnosis. Occasionally, the patient with a galactocele may develop superimposed infection, requiring ultrasound-guided drainage. Hematoma hematoma typically presents after surgery or trauma (Figs. 5 and 5), but it may be spontaneous in a patient on anticoagulant therapy. The age of the blood products determines the specific appearance. hyperacute hematoma may appear as a simple cyst with internal echoes, which rapidly becomes a complicated cyst (Figs. 5 and 5). Fig. 5 Hematoma in woman who sustained thoracic trauma in motor vehicle collision. and, raniocaudal () and mediolateral () images show mixed density and partially circumscribed macrolobulated mass in upper central right breast. and, Ultrasound images obtained same day show complex cyst with solid and anechoic elements and thick wall. There was no demonstrable flow in solid components. Given history of significant chest wall trauma, findings are most consistent with evolving hematoma. W128 JR:194, February 2010

8 ystic Masses of the reast Nevertheless, all hematomas eventually share the common appearance of a complex cyst with internal debris and a thick echogenic wall. There are often avascular mural nodularity and septa. The appearance of a hematoma at MRI is variable depending on the age of the blood products within it. Peripheral enhancement reflects the healing process and inflammation. If the clinical history is suggestive of hematoma, these lesions may be followed to resolution with a I-RS 3 classification. However, if there is no history of recent trauma to account for the imaging findings, aspiration with possible biopsy is warranted, requiring a I- RS 4 classification in some cases. Fat Necrosis Fat necrosis may be seen after surgery, radiation therapy, and trauma. Pathologically, hemorrhage within fat evolves into cystic degeneration, which often has associated calcifications and eventually continues to fibrosis and scar formation. Patients with fat necrosis most often are asymptomatic but occasionally may present with a palpable lump that is tender. t mammography, imaging findings range from vague ill-defined asymmetries and spiculated masses to oil cysts and dystrophic-appearing calcifications. The sonographic appearance of fat necrosis varies according to the chronology of the process and the inciting factor. The appearance can range from a solid mass or complex mass with mural nodules or echogenic bands to an isoechoic or anechoic mass with or without shadowing or posterior acoustic enhancement (Figs. 6 6). Increased echogenicity of the subcutaneous fat and hyperechoic masses almost always indicates a benign finding. However, varying degrees of fibrosis may give an appearance suspicious for malignancy. olor oppler imaging does not reliably permit differentiation of the mass as benign, especially when the lesion shows irregular or spiculated margins. In these cases, biopsy is warranted. The MRI appearance of fat necrosis is variable depending on the stage of the process and often can mimic malignancy (Figs. 6E 6G). oarse calcifications may create signal voids, and fibrosis can appear as distortion with or without spiculation. If there is substantial fibrosis, it can have a variable appearance on T1-weighted sequences, showing high, low, or intermediate signal. When fat predominates, there is central low signal intensity with high signal on fat-suppressed T1-weighted images. However, fat necrosis may mimic malignancy, having progressive-to-rapid contrast enhancement and sometimes rim enhancement. orrelation of the MRI findings with mammography can be helpful when fat necrosis is a diagnostic consideration because most often there are characteristic findings that confirm the diagnosis. The Fig. 6 Fat necrosis. and, Magnified lateral image of left breast () shows low-attenuation mass in operative bed that on ultrasound image () shows complex avascular mass consistent with oil cyst. (Fig. 6 continues on next page) JR:194, February 2010 W129

9 Eisenberg Fig. 6 (continued) Fat necrosis., Magnified lateral image of right breast in different patient shows dystrophic and spherical calcifications in area of prior surgery., On ultrasound, one of these calcified masses from corresponds to anechoic cyst, another appearance of oil cyst. E G, MR images of third patient show low to intermediate signal intensity on unenhanced T1-weighted image (E), intermediate signal on T2- weighted sequence (F), and suspicious enhancement with washout kinetics after administration of gadolinium (G). E findings of lack of internal enhancement on MRI and signal intensity changes of fat on MR images often can avoid biopsy and permit classification of this finding as I-RS 2. F G reast bscess reast abscess is a complication of mastitis, most commonly (but not exclusively) in lactating women. If the infection continues without treatment, the tissues become necrotic and develop into an abscess cavity. Patients with mastitis typically present with fever, chills, breast W130 JR:194, February 2010

10 ystic Masses of the reast Fig. 7 Mastitis., Gray-scale image in breast-feeding patient shows ill-defined complex cyst with solid and hypoechoic elements with low-level internal echoes, consistent with abscess. Notice diffuse overlying skin thickening., Image in another patient shows macrolobulated complex cyst with internal echogenic material and peripheral vascularity, also consistent with abscess. erythema, and tenderness. Imaging is used to differentiate between cellulitis or mastitis and abscess because an abscess will require percutaneous drainage or surgery. Ultrasound is the initial imaging technique for evaluating a suspected abscess because pain typically limits the compression required for mammography. Sonographically, an abscess appears as an oval, lobulated, or irregular-shaped cyst with internal debris with surrounding edema of the skin and subcutaneous tissues (Fig. 7). t color oppler evaluation, the cyst has thick hyperemic walls. olor signal may also be created by motion of debris in the cavity. MRI shows a round or irregular mass with intermediate signal intensity centrally and a low-signal peripheral rind that avidly enhances. On T2- weighted images, there is high signal within the skin and breast parenchyma, consistent with edema. Treatment options for a breast abscess include percutaneous drainage in conjunction with antibiotic therapy. Surgery is necessary for cases that are refractory to antibiotics and percutaneous drainage for markedly multiloculated lesions. Intracystic Papilloma n intraductal papilloma is a common cause of a cyst with a mural nodule. The papilloma obstructs the duct in which it is located and secretes fluid to form a cyst. t this point, the lesion is termed an intracystic papilloma. On ultrasound, a cyst with a mural-based nodule is often seen (Fig. 8). In some cases, the solid component may extend beyond the cyst toward the nipple, and the cyst may contain debris. MRI characteristics of an intraductal papilloma include a distended duct that may have high signal on T1-weighted images if the duct contains proteinaceous debris or hemorrhage. round filling defect may be seen within the duct. Papillomas enhance avidly with gadolinium. Unfortunately, the diagnosis of benign papilloma cannot be reliably made with imaging. Epithelial hyperplasia with atypia, ductal carcinoma in situ, and papil- Fig. 8 Intracystic papilloma. Ultrasound in this 24-year-old woman with palpable lump in right breast showed small vascular mural-based nodule within fluid-filled cyst. ore biopsy with vacuum-assisted device confirmed intracystic papilloma. JR:194, February 2010 W131

11 Eisenberg lary carcinoma may occur within the papilloma or may obstruct the duct, leading to similar imaging findings. Therefore, a biopsy must be performed, and the appropriate classification of this lesion is I-RS 4. Necrotic Neoplasms necrotic neoplasm must always be considered in the differential diagnosis of a complex cyst (Figs. 9 and 9). Necrosis most frequently develops in a rapidly growing invasive ductal carcinoma, producing an irregular mass with a central cystic component (Fig. 9). Peripheral and some internal vascularity associated with the mass can be shown with color oppler interrogation (Figs. 9 and 9E). The irregular margins of the lesion increase the suspicion of malignancy, requiring a classification of at least I-RS 4 and the need for performing a core biopsy. MRI characteristics of a necrotic neoplasm include an irregular or, less commonly, a circumscribed mass with heterogeneous or rim enhancement. Other less common malignancies that should be considered as the cause of a complex breast lesion include medullary carcinoma, which may present as a circumscribed, round, or lobulated mass with a central cystic component; and phyllodes tumors, which appear mammographically as large circumscribed masses and sonographically as circumscribed hypoechoic masses with internal cystic areas. Fig. 9 Necrotic neoplasm., Mediolateral oblique (), craniocaudal (), and magnified mediolateral () images of right breast show multiple irregular masses with associated pleomorphic calcifications. (Fig. 9 continues on next page) W132 JR:194, February 2010

12 ystic Masses of the reast Fig. 9 (continued) Necrotic neoplasm. and E, Ultrasound color images of two of masses show complex cystic lesions with areas of internal avascularity, consistent with necrosis, and other areas of internal vascularity, consistent with viable tumor. Summary ystic lesions are commonly encountered in breast imaging. areful attention to the detailed characteristics of the cystic mass and correlation with patient history and presentation will shape the differential diagnosis and management of the patient. References and Suggested Readings 1. Stavros T, Thickman, Rapp L, ennis M, Parker SH, Sisney G. Solid breast nodules: use of sonography to distinguish between benign and malignant lesions. Radiology 1995; 196: Stavros T. Sonographic evaluation of breast cysts. In: Stavros T, reast ultrasound. Philadelphia, P: Lippincott Williams & Wilkins, 2004: Kopans. reast imaging. Philadelphia, P: Lippincott Williams & Wilkins, ardenosa G. linical breast imaging: a patient-focused teaching file. Philadelphia, P: Lippincott Williams & Wilkins, Tartar M, omstock E, Kipper MS. reast cancer imaging: a multidisciplinary, multimodality approach. Philadelphia, P: Mosby Elsevier, Smith N, Kaelin M, Korbin, Ko W, Meyer JE, arter GR. Impalpable breast cysts: utility of cytologic examination of fluid obtained with radiologically guided aspiration. Radiology 1997; 204: Leung JW, Sickles E. Multiple bilateral masses detected on screening mammography: assessment of need for recall imaging. JR 2000; 175: Taboada JL, Stephens TW, Krishnamurthy S, randt KR, Whitman GL. The many faces of fat necrosis in the breast. JR 2009; 192: merican ollege of Radiology. reast imaging reporting and data system: breast imaging atlas and lexicon. Reston, V: merican ollege of Radiology, 2003 E JR:194, February 2010 W133