Isolated splenic metastasis from right-sided colon adenocarcinoma: a case report

Isolated splenic metastasis from colorectal carcinoma is an exceptionally rare finding, with fewer than one hundred cases reported. Despite its rich vascularization, the spleen is considered an unfavorable site for metastatic spread due to its anatomical configuration, rhythmic contractility, and strong immunologic function. When present, splenic metastases usually occur in the context of disseminated disease and typically originate from left-sided colorectal tumors. We present a case of metachronous isolated splenic metastasis from a right-sided colon adenocarcinoma. A 73-year-old man underwent right hemicolectomy in 2019 for a moderately differentiated cecal adenocarcinoma (pT3N0M0, G2), followed by adjuvant chemotherapy with capecitabine and oxaliplatin. After three years of disease-free follow-up, routine surveillance revealed rising carcinoembryonic antigen (CEA). Abdominal computed tomography demonstrated a 63-mm hypodense splenic lesion consistent with metastasis. The patient underwent laparoscopic splenectomy without complications. Histopathological examination confirmed metastatic well-differentiated intestinal-type adenocarcinoma consistent with colorectal origin. Although extremely rare, splenic metastasis should be considered in patients with a history of colorectal cancer presenting with a solitary splenic lesion. Early identification through regular surveillance allows potentially curative surgery. Splenectomy provides both diagnostic confirmation and therapeutic benefit in selected cases. This report emphasizes the importance of long-term follow-up in colorectal cancer survivors, as early detection of uncommon metastatic sites, such as the spleen, may improve prognosis.