CT Features of the Accessory Spleen

Abstract

Accessory spleens are present in 16% of patients undergoing contrast-enhanced abdominal CT. Typically, accessory spleens appear on CT scans as well-marginated, round masses that are smaller than 2 cm and enhance homogeneously on contrast-enhanced images. When accessory spleens are smaller than 1 cm, their attenuation may be lower than that of the spleen because of partial volume effects. Their most frequent location (22%) is posteromedial to the spleen; anterolateral to the upper pole of the left kidney; and lateral, posterior, and superior to the tail of the pancreas. Familiarity with these characteristic features may differentiate them from other pathologic findings in the upper abdomen.