Accessory spleens are usually asymptomatic, although they may cause hematological disorders associated with hypersplenism, usually after splenectomy. Moreover, cases of hypersplenism occurring secondary to enlargement of an accessory spleen with an unaltered normal spleen have been reported. An accessory spleen can also mimic an intra-abdominal neoplasm. We report a case of hypersplenism that occurred secondary to an increase in the size of the accessory spleen, which was located in the mesentery close to the cecum, mimicking recurrence of previously resected renal carcinoma.