Abstract
In the realm of oncologic reconstructive surgery, local or distant autologous tissue is frequently used to improve function and appearance. Due to advances in microsurgery and intensive care, reconstructive free flap surgery has become the standard treatment for head and neck cancer. However, the complexity of interdisciplinary intervention and prolonged surgical time inevitably increase the risk of cross-contamination, potentially leading to donor site metastasis. According to the literature, tumor transmission to the donor site of free flaps is extremely rare. We present the case of a 54-year-old man with left tongue squamous cell carcinoma. Three months after tumor ablation and reconstruction with a free anterolateral thigh flap, the patient presented with a mass on the donor site of the left thigh, which was proven to be a metastasis. A systemic workup revealed multiple metastases. Six months after reconstruction, the patient died of COVID-19 pneumonia. The incidence and risk factors of donor site metastasis are not well known. The primary causes are direct implantation or hematogenous spread. Cross-contamination is primarily prevented by the surgeon's awareness and avoidance. The development of new-onset lesions at the donor site warrants additional testing to detect systemic disease progression during follow-up.