Intraoperative magnetic seed localisation of non-palpable soft tissue lesions: a monocentric pilot study.

BACKGROUND: Localisation of non-palpable soft tissue lesions remains challenging, particularly in previously treated or anatomically complex regions. Magnetic seed (Magseed®) localisation, widely used in breast surgery, offers a radiation-free alternative to wire or radioactive methods; however, its use in non-palpable soft tissue lesions has not yet been described in the literature. This paper presents the experience of a tertiary cancer centre with the use of magnetic seed in the intraoperative localisation of non-palpable soft tissue lesions, outlining its feasibility, accuracy, and safety. METHODS: All patients who underwent excision of non-palpable soft tissue lesions localised with Magseed® between February 2021 and December 2024 at a tertiary cancer centre were retrospectively reviewed. The primary endpoints were successful placement and retrieval of the seed. Secondary outcomes included dislocation, margin status, operative time, and perioperative complications. RESULTS: Thirty-one seeds were placed in 27 patients (median age 67 years). The median lesion size was 15 mm, and the median depth was 21 mm. All seeds were correctly positioned under ultrasound guidance without complications. The detection rate was 100%, and negative margins were achieved in 97% of cases. Minor perioperative complications occurred in 6% of cases. Operative time was not correlated with lesion depth or BMI but was shorter in lymph node localisations (p = 0.079). CONCLUSIONS: Magnetic seed localisation is a safe, effective, and radiation-free method for non-palpable soft tissue lesions. This pilot series provides the first clinical evidence supporting its feasibility beyond breast surgery and highlights its potential to enhance precision in oncological procedures.