Hypercalcaemic Paraneoplastic Syndrome in a Young Woman with Malignant Phyllodes of the Breast: A Case Report Paraneoplastic syndromes, though uncommon, present systemic effects secondary to primary malignancies or metastases. We presented a case of a 25-year-old nullipara with a left breast malignant phyllodes. Pre-operative investigations revealed hypercalcaemia. Her staging computed tomography scan did not demonstrate any enlarged parathyroid gland. Her serum intact parathyroid hormone level was not raised. After correction with saline hydration, she underwent a left mastectomy, axillary dissection and a supercharged bipedicle TRAM flap. The following day, due to flap congestion, she underwent flap exploration but unfortunately, the flap necrosed. She required temporary coverage with a split-skin graft to allow her post operative sepsis to resolve. She underwent a delayed extended latissimus dorsi myocutaneous pedicled flap for chest wall closure. The cause of hypercalcemia was attributed to be a paraneoplastic syndrome which has not been reported previously in a malignant phyllodes tumor. The hypercalcaemia is postulated to have caused the thrombosis leading to flap failure