Accessory spleen

An accessory spleen is a small nodule of splenic tissue found in some people in the neighborhood of the spleen, and especially in the gastrolienal ligament and greater omentum. Accessory spleens may be isolated or connected to the spleen by thin bands of splenic tissue. They vary in size from that of a pea to that of a plum.

Accessory spleens are congenital foci of normal splenic tissue that are separate from the main body of the spleen. They arise from the failure of fusion of the splenic anlage during the fifth week of fetal life. Accessory spleens are relatively common and are seen in 10–30% of patients at autopsy. Accessory spleens are present in 16% of patients undergoing contrast-enhanced abdominal CT. Most frequent location is posteromedial to the spleen (22%).

The imaging findings are

• Typical appearance of accessory spleens on CT scans are well-marginated, round masses that are smaller than 2 cm and enhance homogeneously.
• Accessory spleens are smaller than 1 cm may display an attenuation lower than that of the spleen because of partial volume averaging.
• An accessory speen may mimic lymphadenopathy and tumors in other abdominal organs.

CT and Ultrasound images demonstrate an accessory spleen

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