Atypical ultrasound appearance of malignant breast nodules

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1 Pictorial essay Medical Ultrasonography 2009, Vol. 11, no. 4, Atypical ultrasound appearance of malignant breast nodules Anca I. Ciurea 1, Cristiana A. Ciortea 2, Carolina Botar-Jid 1, Sorin M. Dudea 1 1 Iuliu Haţieganu University of Medicine and Pharmacy Cluj-Napoca, Romania 2 Emergency County Hospital, Cluj-Napoca, Romania Abstract: Breast cancer represents the most frequent malignancy in women, with more than a million cases of breast cancer diagnosed worldwide each year. Despite the increasing incidence, mortality from breast cancer continues to fall mainly due to earlier detection via mammographic screening but also due to the complementary diagnostic imaging methods. Among these, ultrasound is most frequently used to reach a correct diagnosis. Despite the fact that ultrasound is able to differentiate between benign and malignant breast masses, in practice, there are many situations in which the atypical appearance of a mass leads to misdiagnosis. This is why, in the case of a breast nodule, all the sonographic features should be carefully analysed in order to reach the correct diagnosis and to reduce the rate of false negative results. Key words: breast ultrasound, atypical lesions, ultrasound breast diagnosis Rezumat: Cancerul mamar reprezintă cea mai frecventă afecţiune malignă în rândul populaţiei de sex feminin. În fiecare an sunt diagnosticate peste un milion de cazuri pe tot globul. Deşi incidenţa cancerului mamar continuă să crească, mortalitatea prin cancer de sân se reduce continuu datorită atât screeningului mamografic cât şi completării examenului mamografic cu alte examinări imagistice. Dintre acestea, ecografia este cel mai des utilizată pentru diagnosticul mamar. Deşi în cele mai multe cazuri ecografia poate stabili caracterul benign sau malign al unei leziuni mamare, în practică există numeroase situaţii în care aspectul atipic al acestora poate preta la confuzii de diagnostic. De aceea, în vederea stabilirii unui diagnostic corect, cu reducerea rezultatelor fals negative, în toate cazurile de formaţiuni nodulare mamare evidenţiate ecografic se recomandă analizarea atentă a tuturor caracterelor ecografice ale acestora. Cuvinte cheie: ecografie mamară, leziuni atipice, diagnostic ecografic Invasive breast cancers usually are epithelial tumors of ductal or lobular origin. Invasive ductal cancer, or infiltrating ductal carcinoma (IDC), is the most common form of breast cancer and accounts for 50% to 70% of invasive breast cancers. Typically, it presents as a hard palpable mass, although with increasing use of screening mammography more cancers of this type are diagnosed at a nonpalpable stage. When this cancer does not take on special features, it is called infiltrating ductal carcinoma, NOS (which is an Address for correspondence: Anca Ciurea, Radiology Department, Emergency County Hospital, 1-3 Clinicilor str, , Cluj-Napoca, Romania ancaciurea@hotmail.com abbreviation for not otherwise specified) and it accounts for 50%-70% of all IDC. When infiltrating ductal carcinomas take on differentiated features, they are named according to the features that they display: infiltrating tubular carcinoma (2%-3%), mucinous or colloid carcinoma (2%-3%), medullary carcinoma (5%), invasive cribriform carcinoma (1%- 3%), invasive papillary carcinoma (1%-2%), adenoid cystic carcinoma (1%) and mataplastic carcinoma (1%) [1,2]. Infiltrating lobular carcinoma has a much lower incidence and comprises s about 15% of invasive breast cancers. It has a tendency to be more multifocal. Other invasive histologies of nonepithelial origin, such as breast lymphoma are much less common and together account for less than 10% of all invasive breast cancers [1,2].

2 68 Anca I. Ciurea et al Atypical ultrasound appearance of malignant breast nodules Fig 1. Malignant lesion (IDC NOS) presenting as a hypoechoic mass, inhomogeneous, with ill defined margins. Fig 4. Malignant lesion (IDC NOS) with irregular contour and with posterior shadowing. Fig 2. Malignant lesion (IDC NOS) with hypoechoic spicules. Fig 5. Malignant mass, hypoechoic, ill defined, with hyperechoic rim. Fig 3. Malignant lesion (IDC NOS) with irregular contour and angulated margins. Fig 6. Taller than wide appearance of a malignant nodule. In breast primary malignancies, the invasive ductal carcinoma usually presents on ultrasound as an ill defined mass (fig 1), with irregular contour (spiculated, microlobulated or angulated) (fig 2, fig 3), frequently inhomogeneous due to necrosis within the tumour. Because of the desmoplastic reaction, malignant nodules will cause acoustic shadows and will be surrounded by a hyperechoic rim (fig 4, fig 5). Because of the tendency of invading anatomical structures, they will have a taller than wide appearance

3 Medical Ultrasonography 2009; 11(4): Fig 7. IDC NOS with extended necrosis, mimicking a cystic lesion. Fig 9. Colloid carcinoma exhibiting a thin echogenic capsule and normal through transmission. Fig 8. IDC NOS with well defined contour, echogenic capsule and enhanced-through transmission. Fig 10. Colloid carcinoma with a hyperechoic structure with regard to the surrounding fat. (anteroposterior diameter larger than the horizontal one) (fig 6) [3-7]. Even if the special types of IDC exhibit more frequently atypical ultrasound appearances, IDC NOS can also have special features that can make it difficult to differentiate from a benign lesion. In cases of extended necrosis, large anechoic areas can lead to confusion with simple cysts, intracystic papilloma, abscess, haematoma or lymphoma (fig 7) [8]. IDC NOS with high histologic grade, because of the high cellularity and little desmoplasia, will have enhanced ultrasound transmission and a rather round shape with well defined margins (fig 8) [4, 7, 8]. Pure medullary carcinomas have an ultrasound appearance that is suggestive more for a benign lesion than for malignancy. They are usually circumscribed, well defined lesions, with a thin echogenic capsule and an extremely hypoechoic structure. These characteristics make them difficult to differentiate from cysts or lymphomas [8-10]. Colloid carcinomas, similar to medullary carcinomas, may exhibit a thin echogenic capsule and normal or enhanced-through transmission (fig 9). Lesions less than 1.5 cm in diameter will be iso or hyperechoic with regard to the surrounding fat which, together with the echogenic capsule will give them a fibroadenoma or a complex cystic appearance (fig 10) [8,11-13]. The breast malignancy with the greatest imaging polymorphism is the invasive lobular carcinoma (ILC). Because mammography is most of the times negative, ultrasound is the most important imaging method for the diagnosis of ILC [8,14]. On ultrasound, it can appear as a parenchimal mass with malignant features or, more often, as a hypoechoic area suggestive for diffuse mastopathy or it can only produce minimal architectural distortion (fig 11, fig 12) [4,8]. The alveolar and the solid variants of ILC present more frequently as solid nodules (fig 13). The alveolar variant may have spiculations or a thick echogenic halo while the solid variant is normal or enhanced through transmission (fig 14 a,b) [8,14].

4 70 Anca I. Ciurea et al Atypical ultrasound appearance of malignant breast nodules Fig 11. ILC with subtle ultrasound appearance, mimicking diffuse mastopathy. Fig 14a. ILC, occult on mammography. On ultrasound it appears as multiple hypoechoic masses, with normal through transmission. Fig 12. ILC presenting as attenuation foci with no associated mass. Fig 14b. Same case as in Fig.14a. On elastography the nodules exhibit a mosaic patterns (scor 2), typical for benign masses. Fig 13. Particular type of ILC presenting as a well defined mass, with a thin echogenic capsule, with normal through transmission. Breast lymphoma presents on ultrasound as an extreme hypoechoic mass, well defined, hypevascular at Doppler examination. In the majority of the cases, the Fig 15. Primary breast lymphoma, presenting like a very hypoechoic mass, with low internal echoes and well defined margins. On Doppler ultrasound no blood vessels are depicted. echogenity is so reduced that it can mimic a cystic lesion. Inhomogeneous content or the absence of the blood vessels can make them difficult to differentiate from be-

5 Medical Ultrasonography 2009; 11(4): Fig 16. Primary breast lymphoma, with inhomogeneous echostructure, with no blood vessels on Doppler examination. Fig 18. Malignant fibrous histiocytoma with relatively well defined margins, low internal echoes and enhanced-through transmission, mimicking a cystic lesion. Fig 17. Round, well defined, homogeneous solid lesions, proved to be a malignant fibrous histiocytoma. nign lesions, as cysts, abscesses or haematomas (fig 15, fig 16). Other breast malignancies can also have atypical features for a malignant lesion. They can have an ultrasound pseudocystic appearance, or can mimic a fibroadenoma or other benign lesions (fig 17, fig 18). In all cases in which the benign nature of a breast mass is not certain, all ultrasound features should be carefully analyzed and, if needed, further investigation should be indicated. Bibliography: 1. Diseases of the Breast, in Townsend: Sabiston Textbook of Surgery, 18th ed, Saunders Elsevier, Breast Disease: Benign and Malignant. Medical Clinics of North America, Volume 92, Issue 5, September Stavros AT, Thickman D, Rapp Cl, et al. Solid breast nodules: use of sonography to distinguish between benign and malignant lesions, Radiology 1995;196: Heywang-Kobrunner SH, Schreer I, Dershaw D. Diagnostic breast imaging, 1997, Thieme, Stuttgart New-York. 5. Tohno E, Cosgrove DO, Sloane JP. Ultrasound diagnosis of breast diseases. Churchil Livingstone, Longman Singapore Publishers Pte Ltd, Madjar H. The Practice of Breast Ultrasound. Thieme, Stuttgart-New-York, Ciurea A, Chiorean A. Glanda mamară; În: Badea RI, Dudea SM, Mircea PA, Zdrenghea D. Tratat de Ultrasonografie Clinică; Editura Medicală, Bucureşti 2006, vol II, Stavros AT. Breast Ultrasound, Lippincott Williams and Wilkins, Cheung YC, Chen SC, Lee KF, Wan YL, Ng SH. Sonographic and pathologic findings in typical and atypical medullary carcinomas of the breast. J Clin Ultrasound. 2000,28: Sobrino-Mota V, Lagarejos-Bernardo S, Varela-Mezquita B, Castro Y, Segura-González C, Pérez-Milán F. Unusual sonographic findings in a case of atypical medullary inflammatory carcinoma of the breast. J Clin Ultrasound. 2008;36: Lam WW, Chu WC, Tse GM, Ma TK. Sonographic appearance of mucinous carcinoma of the breast. AJR Am J Roentgenol. 2004;182: Memis A, Ozdemir N, Parildar M, Ustun EE, Erhan Y. Mucinous (colloid) breast cancer: mammographic and US features with histologic correlation. Eur J Radiol. 2000;35: Chopra S, Evans AJ, Pinder SE, et al. Pure mucinous breast cancer-mammographic and ultrasound findings. Clin Radiol. 1996;51: Whitman GJ, Huynh PT, Patel P, Wilson J, Cantu A, Krishnamurthy S. Sonography of invasive lobular carcinoma. Ultrasound Clin, 2006;1; Wei Tse Yang. Sonography of unusual breast neoplasms. Ultrasound Clinics 2006;1: