Abstract P3-01-11: Discoloration after injection of super paramagnetic iron oxide (SPIO) for sentinel node biopsy. A long term qualitative follow-up study

Background SPIO has a similar detection ratio as Technetium99 and Patent Blue to identify sentinel nodes (SN). No allergic reactions have been observed and no nuclear medicine facilities are needed, making logistics easier. At the Academic Hospital in Uppsala, Sweden, SPIO has been used routinely for three years. After breast conserving surgery (BCS) many women developed a brownish discoloration at the injection site. The discoloration stays for a long time. To study the patient-experienced cosmetic discomfort and the natural history of the discoloration we followed our first 153 BCS women for more than two years. After modifying the technique of injection we registered the discoloration in the following 115 women. Methods All women injected with a retro-areolar injection of SPIO between April 2015 and October 2016 were included. The women were telephone interviewed every third month. The size of the discoloration was self-assessed and the cosmetic discomfort was classified by a scale from 0 (no discomfort) to 5 points (very discomforting). Photos were taken in selected cases after 1-2 years. Between November 2016 and April 2017, a deeper, para-tumoral injection was used and discoloration was noted 3 weeks after surgery. Results Ninety of 153 women (58.8%) developed a discoloration after a retro-areolar injection. The mean size was 26.1cm2 (2-100cm2). The discoloration had vanished in 6.8% and 11.4% of the women after 1 and 2 years, respectively. The mean size of the discolorations was 18.2cm2 (1-66cm2) and 13.6cm2 (1-66cm2) after 1 and 2 years. The intensity of the color was continuously fading. The cosmetic discomfort was assessed as 2.2 points after 1 year and 1.0 after 2 years. Of 115 women with a deeper injection, 32.2% developed a discoloration with a mean size of 13.1cm2 (1-36cm2), three weeks after surgery. The incidence and size of the discolorations were statistically significantly less and smaller after a deeper injection (p