Pseudoaneurysm of a Lymph Node's Vasculature in the Axillary Tail of the Breast.

We present the rare complication of pseudoaneurysm within the vasculature of a lymph node as a result of core needle biopsy (CNB) of a lymph node within the axillary tail of the breast. The pseudoaneurysm developed within the feeding artery of a lymph node, and to our knowledge, this is the first such reported case. Pseudoaneurysm should be considered in the differential diagnosis of a mammographically new or enlarging asymmetry. Our case also emphasizes the importance of ultrasound color Doppler in establishing the correct diagnosis.