Malacoplakia is a histiocytic inflammatory response that may be associated with colorectal tumors. We report the case of a 65-year-old male taking steroids for a severe pulmonary disease. He presented with a rectosigmoid tumor that seemed to infiltrate the urinary bladder and the sacrum on the preoperative CT scan and echography and at laparotomy. A low anterior resection en bloc with a partial cystectomy was performed. The pathologic analysis showed a pT3pN0 adenocarcinoma with an extensive malacoplakia infiltrating the bladder and the pericolic and perirectal tissues. This case report emphasizes the overstaging that malacoplakia may induce and underlines a situation the surgeon may possibly confront. Our observation confirms the association of malacoplakia, colorectal carcinoma, and steroid treatment.