Case Report: A rare presentation of prostate cancer with peritoneal carcinomatosis and malignant ascites complicated by tumor lysis syndrome [version 1; peer review: 1 approved with reservations]

Background: Only 32 cases of prostate cancer with peritoneal carcinomatosis and ascites have currently been reported in the literature. We present the first reported case of prostate cancer with peritoneal carcinomatosis and malignant ascites whose treatment was complicated by tumor lysis syndrome along with a literature review evaluating similar cases. Case: We present a rare case of a 78-year-old retired Caucasian male with recurrent metastatic prostate cancer and malignant ascites. He had previously received definitive radiotherapy for localized prostate cancer but presented with bilateral hydronephrosis and right-sided bladder wall thickening 10 years later. He had imaging evidence of locoregional recurrence with elevated prostate specific antigen (PSA) and was initiated on combined androgen blockade with intramuscular leuprolide and oral bicalutamide. After being transferred to Scripps Clinic, he was found to have a solitary right upper lobe pulmonary lesion for which he completed stereotactic body radiation therapy. Then, 10 months later, he developed new onset malignant ascites and was treated with two cycles of intravenous docetaxel. Treatment resulted in improvement in his ascites and reduction in PSA. Unfortunately, his course was complicated by tumor lysis syndrome, encephalopathy, Escherichia coli bacteremia, and a fatal saddle pulmonary embolism. Conclusions: (1) Occurrence of ascites in prostate cancer patients is associated with worse prognosis than non-ascitic variants. (2) More common etiologies of ascites must be evaluated for. (3) Ascitic fluid prostate specific antigen (PSA) measurement may aid in diagnosis of malignant ascites in cases with diagnostic uncertainty. (4) Patients with advanced disease may benefit from combined hormonal and cytotoxic therapies. (5) Awareness of the occurrence of tumor lysis syndrome (TLS) in patients treated for prostate cancer can help identify patients in whom prophylaxis would be beneficial.