Intrasplenic metastasis of appendiceal low-grade mucinous neoplasm – A case report and review of the literature

• Low-grade mucinous neoplasm may lead to pseudomyxoma peritonei. • By definition LAMN does not metastasize. • We report a case of splenic LAMN metastasis. • Literature review of pseudomyxoma recurrence reveals that LAMNs might indeed recur in extraperitoneal locations. • Definition of LAMN and oncological surveillance should be discussed and adapted. Low-grade appendiceal mucinous neoplasms (LAMNs) may lead to pseudomyxoma peritonei and require specialized surgical therapy. By pathological definition, these tumor entities exhibit neither invasive growth nor develop systemic or lymph node metastases. We report the case of a 43-year-old female presenting with a metachronous splenic metastasis of low-grade pseudomyxoma peritonei four years after surgical therapy. The patient was treated successfully via laparoscopic splenectomy. While the spleen itself is an extremely rare location for metastasizing colonic cancer, a LAMN metastasis in this location has not been previously described. A literature review of pseudomyxoma recurrence reveals that LAMNs might indeed recur in extraperitoneal locations, questioning their pathophysiological definition of non-metastasizing behavior.