PURPOSE: To describe the mammographic and sonographic appearance of a pattern of spiculation of the contour of axillary lymph nodes. MATERIALS AND METHODS: Eleven cases of axillary nodes with spiculated contour were prospectively identified on routine mammograms. All cases were in women with breast cancer. Sonograms of axillary nodes were available in three cases. Medical records were reviewed, and histologic and nodal histopathologic findings and patient outcome were correlated. RESULTS: All women had primary, invasive breast carcinoma. Although disease was evident mammographically, four of nine women for whom the results of the physical examination were known did not have palpable adenopathy. Nodes were iso-to hyperdense (compared with breast parenchyma) on mammograms and were hypoechoic with irregular margins on sonograms. The spiculated pattern of the nodes correlated with extension of metastatic tumor in axillary nodes into perinodal fat. At a mean follow-up of 17 months, one patient was dead of disease, eight were alive with disease, and two were alive without disease. CONCLUSION: A pattern of spiculated axillary adenopathy in a patient with breast cancer appears to be consistent with extranodal extension of tumor into perinodal fat. This finding suggests a biologically aggressive tumor with a poor prognosis.
