Development of a surgical algorithm by using pre-operative imaging to predict mammoplasty cosmetic outcomes for large non-malignant tumours.

Background: Use of mammoplasty for resection of large non-malignant tumours is not widely described. We aim to determine the optimal tumour to breast size ratio cut-off in this group of patients undergoing mammoplasty which could achieve satisfactory cosmetic outcomes.

Methods: Patients who underwent mammoplasty from May 2014 to June 2017 for biopsy-proven large non-malignant tumours were included in the study. The demographics, tumour to breast size ratios, histological features and cosmetic outcomes of these patients were assessed. The tumour to breast size ratio was estimated in ten-percentiles of the relative volume of the tumour to the overall breast size based on ultrasound and/or mammogram images.

Results: Ten patients were recruited. Median age was 40 years old (range, 14-55 years old). One, four and five patients underwent vertical, wise pattern and round block mammoplasties respectively. The median tumour to breast size ratio was 55% (range, 20-90%). Histology revealed phyllodes and giant fibroadenoma in six and four patients respectively. Margins were clear in all cases. Mean weight and average maximum size of surgical specimen was 357.9 g (range, 28-1,186 g) and 99.3 mm (range, 35-165 mm) respectively. One patient developed partial nipple necrosis which was treated conservatively. All the patients with an estimated tumour to breast size ratio up to 70% reported good to excellent cosmetic outcomes, except for one patient who had a large tumour occupying 90% of her breast.

Conclusions: Mammoplasty can be used successfully in patients with large non-malignant tumours. However, in patients with tumours occupying more than 70% of the breast, mammoplasty alone may not yield a good cosmetic outcome.