What happened, in summary

A 51-year-old woman presented with a palpable lump in the left breast. Mammography and ultrasound showed an irregular suspicious mass in the upper outer quadrant at the 2 o'clock position, measuring about 0.8 x 1.3 x 1 cm. Core biopsy confirmed grade II invasive lobular carcinoma that was ER-positive, PR-positive, HER2-negative, with Ki-67 of 20%. Fine-needle aspiration of a left axillary lymph node was positive for metastasis, confirming node-positive disease rather than a purely localized presentation. The clinical challenge became sequencing cancer treatment safely around a biopsy-related vascular complication. Five weeks later, at the oncology center, the breast surgeon felt 2 lumps. Repeat ultrasound confirmed the known cancer but also found a separate anechoic, blood-flow-filled mass at the 1 o'clock position. Doppler imaging showed it was connected to an adjacent blood vessel through a narrow neck, consistent with a biopsy-related pseudoaneurysm rather than a second tumor. The multidisciplinary team planned neoadjuvant chemotherapy followed by surgical excision and sentinel lymph node biopsy, but the pseudoaneurysm had to be treated first because of bleeding risk. Local compression and sonographic-guided compression did not stop the flow. An interventional radiologist then injected thrombin-JMI under ultrasound guidance, using two 1 mL injections, and Doppler imaging confirmed complete thrombosis. Her hemodynamics remained stable, and she was discharged with breast-surgery follow-up. At 3-month follow-up, the pseudoaneurysm had regressed, allowing the planned cancer treatment pathway to proceed. No post-treatment cancer response was available in the follow-up. At that point, the immediate issue was safe preparation for planned therapy rather than documenting response to treatment.