An Improbable Case of Ascites.

Prostate cancer is the most frequent malignancy seen in males, with about 15% of cases showing metastatic disease at diagnosis, most commonly in bones (vertebrae, ribs, long bones). However, peritoneal metastasis with malignant ascites is extremely rare and may be overlooked by physicians. We report the case of a 77-year-old man presenting with symptoms of abdominal distension, nausea and weight loss. Abdominal ultrasound and computerised tomography confirmed ascites, peritoneal carcinomatosis and an enlarged prostate. Serum and ascitic prostatic-specific antigen were both elevated. Prostate biopsy identified a prostate adenocarcinoma, while biopsy of a peritoneal implant identified a prostate cancer metastasis, which responded well to hormonal therapy. LEARNING POINTS: Prostate cancer is the most frequent malignancy found in men, often metastasising to bones and lymph nodes.Although a rare site of metastasis, peritoneal cancer should be suspected when encountering a case of malignant ascites, in order to not delay diagnosis and treatment.Despite the generally poor prognosis of this malignancy, early diagnosis and hormonal treatment may lead to good clinical, symptomatic and analytical outcomes. © EFIM 2020.