Pseudomyxoma peritonei is a rare and poorly understood form of disease characterized by mucin deposits in the peritoneum. The term includes a broad range of neoplasms with different patterns of evolution, from benign to borderline or even to malignant lesions. The disease may be asymptomatic until advanced stages. We present the case of a 65-year-old patient who presented for pain in the right hemiabdomen, after a trauma by falling from small height. Abdominal imaging studies oriented the diagnosis to a traumatic disease. At laparotomy, a mucinous tumor attached to the right colon was discovered. The main particularity of the case is that the origin of the pseudomyxoma could not be identified.