Axillary lymph nodes: mammographic, pathologic, and clinical correlation.

OBJECTIVE The purpose of this study was to determine the cause and frequency of axillary abnormalities seen mammographically and to evaluate the imaging characteristics of lymphadenopathy that are associated with malignancy. MATERIALS AND METHODS Ninety-six axillary abnormalities seen mammographically in 94 patients were retrospectively reviewed and correlated with the clinical diagnoses and pathologic results found in the medical records. For each abnormality, the length, margins, and presence of microcalcifications were noted. Logistic regression was used to determine an association between these findings and status (benign or malignant). RESULTS Seventy-six of 94 patients had lymphadenopathy. Eighteen of 94 patients had an abnormality other than lymphadenopathy. Because two of these 94 patients had more than one abnormality, a total of 96 abnormalities occurred, 20 of which were due to an abnormality other than lymphadenopathy. Regarding the 76 cases of lymphadenopathy, the most frequent diagnosis was nonspecific benign lymphadenopathy in 29% (n = 22) of cases, followed by metastatic breast cancer in 26% (n = 20) and chronic lymphocytic leukemia or well-differentiated lymphocytic lymphoma in 17% (n = 13). Other causes (n = 21) included collagen vascular disease, lymphomas other than well-differentiated lymphocytic lymphoma, metastatic disease from nonbreast primary site, metastatic disease from unknown primary site, sarcoidosis. HIV-related lymphadenopathy, and reactive lymphadenopathy associated with a breast abscess. An association between length of nonfatty lymph nodes and malignant status was statistically significant at the .001 level. When a length greater than 33 mm was used as a predictor of malignancy, the specificity and sensitivity were 97% and 31%, respectively. We found an association between malignancy and nonfatty lymph nodes with ill-defined or spiculated margins (p = .053). Regarding the 20 abnormalities other than lymphadenopathy, epidermal cysts (n = 7) were most prevalent. CONCLUSION The most common axillary abnormality revealed on mammography was abnormal lymph nodes. Homogeneously dense (nonfatty) axillary lymph nodes were strongly associated with malignancy when the lymph nodes were longer than 33 mm, had ill-defined or spiculated margins, or contained intranodal microcalcifications. However, our study confirmed that in most cases benign and malignant lymph nodes cannot be distinguished from each other mammographically.