Causes of Varied Internal Echo Patterns in Ultrasound Imaging of Breast Lymphoma

Background Ultrasound (US) imaging of breast lymphoma often reveals a variety of internal echo patterns, making differentiation from breast cancer challenging. This study aimed to correlate pathological findings with US imaging features of breast lymphoma to enhance biopsy accuracy and diagnostic precision. Materials and methods We retrospectively analyzed 37 lesions (36 cases) with available US images and needle biopsy pathology specimens from breast lymphoma patients at our hospital between 2010 and 2021. The area ratios of tumor cells, mammary gland tissue, and adipose tissue in pathology specimens were compared with internal echo levels on US. Additionally, we assessed US images during the healing process in cases with complete resolution following treatment. Results US identified 34 of 37 lesions (92%) as masses. Of these, 23 (68%) exhibited mixed internal echoes, while 11 (32%) were hypoechoic. Among the mixed echo lesions, 8 (24%) displayed a mixed hyper-to-hypoechoic pattern, and 15 (44%) showed a mixed iso-to-hypoechoic pattern. Pathological analysis revealed that the tumor cell area ratio was highest in hypoechoic masses, mammary gland tissue ratio was highest in mixed iso-to-hypoechoic masses, and adipose tissue ratio was highest in mixed hyper-to-hypoechoic masses. During healing, the mass changed to non-mass abnormalities in 10 cases (77%) and decreased in size while retaining its shape in 3 cases (23%). Conclusion The internal echo patterns of breast lymphoma varied depending on three factors: the proportion of tumor cells; the presence of tumor cell low-density areas; and adipose tissue infiltration. Hypoechoic areas likely reflected tumor cells, isoechoic areas mammary gland tissue, and hyperechoic areas adipose tissue infiltration. These findings suggest that biopsy from hypoechoic regions is recommended for accurate diagnosis.