Teaching Case

A 53-year-old woman without any significant medical history was referred to our department to undergo vacuum-assisted breast biopsy (VABB) of the area with scattered microcalcifications in the right breast diagnosed on mammography in the outside medical facility.

The patient underwent VABB of the region of the right breast containing suspicious calcifications under mammographic guidance (Figure 1). After the procedure, the patient developed excessive bleeding at the biopsy site. Steady pressure with a gauze pad was applied and the bleeding stopped. Unfortunately, later that day, the patient once again noticed bleeding at the incision site and swelling of the breast tissue, therefore, she was referred to the emergency department.

Physical examination revealed a painful, palpable pulsatile mass in the right breast.

The initial breast ultrasound (US) scan showed heterogeneous soft tissue hematoma with central hypo-/anechoic areas. Color Doppler (CD) ultrasound with spectral analysis showed swirling high-velocity blood flow at the centre of the lesion with a typical “to-and-fro” pattern (Figure 2A-C).

A follow-up US examination was scheduled two days later, which revealed that the lesion had remained the same size and persistent flow through the neck and the lumen was still present. Contrast Enhanced Ultrasound (CEUS) scanning showed contained extravasation of the microbubbles through the vascular injury (Figure 3A-C).

Magnetic Resonance Imaging (MRI) revealed the lesion to be adjacent to the lateral thoracic artery (Figure 4A-B).

A follow-up US examination one week later showed moderate regression of the hematoma size and no detectable blood flow at the site of the previously described lesion (Figure 5).

Pseudoaneurysm (PSA) emerges as a result of damage to an arterial wall, the leakage of blood outside the vessel, and the presence of hematoma bounded by the surrounding tissue. Cases of PSA associated with breast needle biopsy are rare [1]. To the best of our knowledge, this is the first case report of PSA of the lateral thoracic artery using CEUS.

PSAs may be asymptomatic or they can present with local and systemic signs and symptoms, such as palpable thrill, audible bruit, pulsatile mass, necrosis of the overlying skin and subcutaneous tissue, oedema and deep vein thrombosis. The most serious complication from PSA is a rupture [2].

Conventional angiography remains the gold standard method for diagnosing PSA, however, duplex Doppler US, Computed Tomography Angiography (CTA) and Magnetic Resonance Angiography (MRA) are also considered effective for noninvasive detection [3].

B-Mode US shows an anechoic or hypoechoic sac adjacent to the damaged artery, allowing measurement of the size and the neck of the PSA [3]. Diagnosis is established by Doppler US, which shows a typical “yin-yang” sign caused by the swirling motion of blood. The hallmark sign is demonstrated by the “to-and-fro” spectral waveform pattern in the neck of the PSA, with “to” representing blood entering the pseudoaneurysm in systole, and the “fro” representing blood exiting the pseudoaneurysm during diastole [2].

CEUS is an emerging method in recent years that has shown the ability to detect contrast agent extravasation, therefore it has been successfully applied to evaluate traumatic and iatrogenic pseudoaneurysms [4].

NECT scans show a low attenuated mass in contact with the damaged artery. CTA shows PSA as a well-defined round or oval collection filled with contrast material [3].

While MRA may be useful for patients with renal failure and a history of iodine allergy, it is not typically the first-line method for diagnosis of PSA due to its cost, availability, patient conditions, and long acquisition time [3].

Treatment options for PSAs include observation with external pressure dressing, ultrasound guided focused compression, percutaneous thrombin injection, endovascular embolization and stenting, and open surgical repair [3].

As there are no specific guidelines for treating breast PSA after VABB, and given our patient’s insignificant medical history and lack of anticoagulant therapy, we chose a conservative approach and scheduled follow-up US examinations.

Clinical suspicion of PSAs can only be confirmed through a thorough physical examination and diagnostic imaging.

Written informed patient consent for publication has been obtained.