A Case of Ectopic Spleen Transplanted Into the Sigmoid Colon and Pelvic Peritoneum

Ectopic spleen (ES) is a rare complication of autologous transplant following spleen injury. Autopsy studies suggest that the true incidence rate could be as high as 67%, though only 5%-10% of patients require clinical intervention. This case report describes a highly cautionary case of ES, with an extremely long latent period. The patient presented with dull lower abdominal pain 24 years after undergoing a splenectomy. An ultrasound examination revealed a round-shaped, solid mass measuring 1.6 × 2.5 cm adjacent to the right ovary. Following laparoscopic surgery, a 2.5 × 1.5 cm mass on the surface of the sigmoid colon and a 1.0 cm dark red nodule on the pelvic floor were completely removed. Pathological and immunohistochemical examinations confirmed that both lesions were splenic tissue. This case highlights the fact that the latent period of ES can last for decades. For patients with a history of splenectomy, any new pelvic or abdominal masses should be included in the differential diagnosis of ES. We urge the implementation of standardized long-term follow-up mechanisms combined with multimodal imaging techniques for a comprehensive assessment in order to effectively avoid misdiagnosis and overtreatment.