Dynamic computed tomography findings of an accessory spleen in the pelvis: a case report

Hiroshi Ota, Yasutomo Ojima, Daisuke Sumitani, Masazumi Okajima

We report the case of a 60-year-old man with an accessory spleen in the pelvis. He visited our outpatient clinic because of abdominal discomfort. Computed tomography (CT) showed an enhanced mass (40 mm in diameter) in the pelvis. Preoperative diagnosis was difficult even after magnetic resonance imaging and colonoscopy. The patient underwent surgery for suspicion of a gastrointestinal stromal tumor or malignant lymphoma of the rectum. Intraoperative findings showed a mass in the pelvis and a long cord-like tissue reaching the mass and arising from the great omentum; the mass was excised. Histopathologic examination indicated that the mass was splenic tissue, and feeding vessels were found in the cord-like tissue, which were determined to be derived from the left gastroepiploic artery and vein. Thus, we diagnosed it as an accessory spleen in the pelvis. An accessory spleen is not rare and can occur anywhere in the abdominal cavity. However, an accessory spleen in the pelvis is an infrequent finding, and only 9 other cases of an accessory spleen in the pelvis have been reported. Therefore, it is very difficult to make a correct diagnosis preoperatively. However, 7 of the 9 cases (77.8 %) of a pelvic accessory spleen had vascular pedicles from the great omentum or splenic hilum as feeding vessels; hence, determining the feeding blood vessels on dynamic CT may be useful for diagnosing an accessory spleen in the pelvis. Additionally, if the accessory spleen is symptomatic or has a vascular pedicle, surgeons should attempt to resect the accessory spleen in the pelvis using minimally invasive laparoscopy.