Splenic lymphangiomas, per se, are exceedingly rare, benign congenital malformations of lymphatic vessels, typically diagnosed in childhood or incidentally in adulthood. Appendiceal mucinous neoplasms (AMNs) are also infrequent, often asymptomatic, and usually discovered incidentally. To date, the co-occurrence of these two distinct primary lesions in the same patient has not been previously reported. We present the case of an 83-year-old Turkish female who underwent emergent abdominal surgery for an acute abdomen secondary to a strangulated left diaphragmatic herniation. Multiple perforations were identified in the transverse colon, accompanied by widespread ischemia involving the terminal ileum, cecum, and right colon. Upon laparotomy, a diaphragmatic defect measuring approximately 10 cm in diameter was identified in the left hemidiaphragm. The herniated abdominal viscera were meticulously reduced and examined, and multiple perforations were identified in the transverse colon, accompanied by widespread ischemia involving the terminal ileum, cecum, and right colon. An emergent splenectomy was performed due to severe ischemia and irreparable structural damage observed within the compromised hernia sac, with the resection of the terminal ileum, the ascending, and transverse colon. During the operative intervention, both a splenic lymphangioma and a low-grade AMN were incidentally discovered. The histological diagnosis was confirmed with factor VIII-related antigen (factor VIII-R antigen) immunohistochemical positivity. The patient, unfortunately, succumbed on the fifth postoperative day due to progressive multi-organ failure. This report documents the first known instance of the simultaneous identification of splenic lymphangioma and AMN as primary lesions in a single patient. This unique case underscores the critical importance for surgeons to remain vigilant for unexpected pathologies and highlights the necessity of a multidisciplinary approach in evaluating rare incidental findings for appropriate classification and follow-up.