Advanced Leiomyosarcoma of the Retroperitoneal Space in a Kidney Transplant Recipient with a History of Peritoneal Dialysis: A Case Report.

BACKGROUND Leiomyosarcoma frequently occurs in patients who are on immunosuppressive therapy. It is the second most common sarcoma in this population and is often associated with Epstein-Barr virus (EBV) infection. We present a case of advanced leiomyosarcoma of the retroperitoneal space in a kidney transplant recipient and discuss additional risk factors for oncogenesis. CASE REPORT A 44-year-old woman with a history of peritoneal dialysis and kidney transplantation was diagnosed with multiple liver lesions. PET-CT scanning showed a metabolically active tumor in the left lumbar region with numerous liver focal lesions. The histological examination of the liver lesion biopsy identified advanced retroperitoneal leiomyosarcoma with a high proliferative index and liver involvement. Unexpectedly, the relation with EBV infection was not proven. The patient was treated with first-line doxorubicin, with the simultaneous reduction of immunosuppression. Owing to disease progression after 6 cycles, the patient received second-line chemotherapy based on gemcitabine and docetaxel, which was terminated owing to unacceptable toxicity, despite an observed response. Third-line trabectedin-based therapy with good tolerance and stabilization of disease after 20 months was being maintained at the time of this report. CONCLUSIONS The increased cancer mortality in solid-organ transplant recipients requires an individualized approach and increased post-transplantation screening according to additional specific cancer risk factors. A further consideration is the hypothetical relevance of long-term peritoneal membrane irritation in peritoneal dialysis patients.