Sonography of Invasive Lobular Carcinoma

Predictors of Malignancy in Hyperechoic Breast Lesions

OBJECTIVES

Hyperechogenicity has been strongly associated with benign breast lesions. Although it is correct in most cases, hyperechogenicity must not always be considered synonymous with benignancy, as hyperechoic breast cancers do occur. The purpose of this study was to review clinical and imaging characteristics of hyperechoic breast lesions, looking for features associated with malignancy.

METHODS

Institutional Review Board approval was granted for this research. A total of 19,417 sonographic examinations were performed between January 2009 and June 2013. Among these, hyperechoic lesions with histologic diagnoses, stability on long-term followup, or characteristic imaging appearances were included in the study. The patients' clinical charts, mammograms, and sonograms were reviewed. The clinical and imaging features were recorded, and the data was analyzed by the χ(2) test, Fisher exact test, and independent-samples t test, looking for statistically significant predictors of malignancy.

RESULTS

Among the 19,417 scans, 42 patients (0.2%) with 44 hyperechoic lesions were identified. Twenty-six lesions fulfilling the inclusion criteria were included in the study: 5 malignancies (3 invasive ductal carcinomas, 1 invasive lobular carcinoma, and 1 invasive mucinous cancer) and 21 benign lesions. An irregular shape, a nonparallel orientation, and noncircumscribed margins were significantly associated with the risk of malignancy (P = .002, .02, and .01, respectively).

CONCLUSIONS

A hyperechoic breast lesion must not always be assumed to be benign. Instead, a full sonographic assessment according to the American College of Radiology Breast Imaging Reporting and Data System descriptors is needed for correct characterization and avoidance of misdiagnosis.

Evolving concepts in breast lobular neoplasia and invasive lobular carcinoma, and their impact on imaging methods

Invasive lobular carcinoma (ILC) and lobular neoplasia (LN) are two distinct conditions that still pose challenges regarding to their classification, diagnosis and management. Although they share similar cellular characteristics, such as discohesive neoplastic cells and absence of e-cadherin staining, they represent completely different conditions. LN encompasses atypical lobular hyperplasia (ALH) and lobular carcinoma in situ (LCIS), which are currently considered risk factors and non-obligatory precursors of breast neoplasia. These lesions are diagnosed as incidental findings in percutaneous biopsies or appear as non-specific clusters of punctate calcifications in mammograms. ILC is the second most common breast malignancy and has typical histological features, such as infiltrative growth and low desmoplasia. These histological features are reflected in imaging findings and constitute the reasons for typical subtle mammographic features of ILC, as architectural distortion or focal asymmetries. Ultrasonography (US) may detect almost 75 % of the ILCs missed by mammography and represents the modality of choice for guiding biopsies. Magnetic resonance imaging (MRI) exhibits a high sensitivity for the diagnosis of ILC and for detecting synchronous lesions.

Teaching Points

• LN includes ALH and LCIS, risk factors and non-obligatory precursors of breast cancer.

• Absence of e-cadherin staining is crucial for differentiation among ductal and lobular lesions.

• ILC has typical histological features, such as infiltrative growth and low desmoplasia.

• Mammographic features of ILC are often subtle and reflect the histological features.

• MRI exhibits a high sensitivity for the diagnosis of ILC and for detecting synchronous lesions.