Why is isolated spleen metastasis a rare entity?

Primary and metastatic tumors of the spleen are uncommon, excluding involvement by lymphoma. Isolated spleen metastasis from other organs is a rare incident. Herein, we report the case of a 59-year-old man who developed isolated splenic metastasis from ascending colon cancer. The patient underwent right hemicolectomy for T3N1M0 tumor of the ascending colon. During the postoperative follow-up, increasing serum level of carcinoembryonic antigen was observed. Furthermore, abdominal computed tomography scan showed a splenic tumor measuring 4 cm. Curative splenectomy was performed. Pathologic investigation confirmed the adenocarcinoma metastasis. The interesting point of our report is that the spleen metastasis arose from the ascending colon. This report is the third described case in the literature of isolated spleen metastasis from a right colon carcinoma.